CN114132885A - Leadless packaging structure and method of high-temperature-resistant sensor - Google Patents

Abstract

Translated fromChinese

本发明公开了一种耐高温传感器的无引线封装结构及方法，该无引线封装结构包括传感器芯片、用于支撑传感器芯片的传感器壳体以及设置在传感器壳体上的金属引脚，所述金属引脚通过耐高温导电层与传感器芯片的金属电极相连，该金属电极外置在传感器壳体表面或内置于传感器壳体。本发明一方面解决了常规金属引线键合封装技术在高温环境中可靠性蜕化甚至失效的问题，另一方面，简化了封装引线方式，操作简单、成品率高，在实际使用中可靠性高，并且适合批量生产、成本低，具有很高的性价比。同时，本发明通过选择并简化封装材料，提高了传感器在高温环境中的工作稳定性和长期可靠性，并且传感器芯片通过采用齐平封装，具有动态响应特性好的优点。The invention discloses a leadless packaging structure and method for a high temperature resistant sensor. The leadless packaging structure includes a sensor chip, a sensor housing for supporting the sensor chip, and metal pins arranged on the sensor housing, the metal The pins are connected with the metal electrodes of the sensor chip through the high temperature resistant conductive layer, and the metal electrodes are externally arranged on the surface of the sensor housing or built into the sensor housing. On the one hand, the invention solves the problem that the reliability of the conventional metal wire bonding packaging technology degrades or even fails in a high temperature environment; And it is suitable for mass production, low cost and high cost performance. At the same time, the invention improves the working stability and long-term reliability of the sensor in a high temperature environment by selecting and simplifying the packaging material, and the sensor chip has the advantages of good dynamic response characteristics by adopting flush packaging.

Description

Leadless packaging structure and method of high-temperature-resistant sensor

Technical Field

The invention relates to a high-temperature-resistant sensor, in particular to a leadless packaging structure and a leadless packaging method of the sensor.

Background

The high temperature resistant sensor has very important application in many industries and fields, such as a high temperature resistant pressure and vibration sensor for detecting the high temperature pressure and vibration in an aircraft engine, a high temperature resistant pressure sensor for measuring the pressure of a loop of a high temperature reactor of a nuclear power station, and a high temperature pressure and vibration sensor for monitoring the operation safety of a high temperature industrial reaction kettle and a smelting tower.

Therefore, the high-temperature-resistant sensor can normally work in a high-temperature environment, and the key problems are that: (1) the sensor chip can normally work in a high-temperature environment, and (2) the sensor packaging structure can normally play roles of supporting, electric connection, sealing and the like in the high-temperature environment. With the progress of the technology, the sensor chip material capable of normally working at high temperature is continuously discovered, and the first key problem of the high-temperature-resistant sensor is effectively solved. However, the sensor packaging structure often involves the combination and the fixed connection of multiple materials, and the problems of inconsistent thermal expansion of heterogeneous materials, high-temperature oxidation of materials, softening and falling of connecting pieces and the like are easily caused at high temperature, so that the supporting structure of the sensor chip fails, the electric connection is short-circuited or broken, even the sensor chip is broken, and the like, and the performance of the sensor is deteriorated or even permanently fails.

The most important ring in the sensor package is to form an effective electrical connection between the electrode of the sensor chip and the electrode on the package structure, so that the signal measured by the sensor chip can be smoothly transmitted. The current common packaging method is to use metal wire bonding for connection. For example, chinese patent CN105236343A discloses a dielectric isolation type pressure sensor package structure, in which a pressure sensor package module with a MEMS chip is connected with a lead wire by wire bonding. The connection mode has a simple structure and is convenient to operate, but when the connection mode is used in a high-temperature environment, bonding points between the leads and the sensor packaging module and between the leads and the wires are easy to fall off due to high-temperature softening, and the risk of failure exists.

In order to solve the problems of metal wire bonding, chinese patent CN102928150A discloses a leadless packaged metal film pressure sensor, in which a sensor chip is connected with a glass sealing cover in a bonding manner, and the leadless packaged metal film pressure sensor is manufactured by forming a through hole corresponding to a lead pad of the sensor chip on the glass sealing cover, a conductive metal material filled in the through hole, and a conductive metal lead pin inserted into the through hole filled with the conductive metal material, and performing vacuum annealing. The packaging mode that adopts in this patent has effectively solved the not high temperature resistant problem of metal wire bonding formula encapsulation, but has two aspects of problem in actual operation: (1) due to the small size of the MEMS chip, the sizes of the lead bonding pad and the corresponding through hole are very small (in micron order), the whole through hole is difficult to be effectively filled with the conductive metal material due to the micropore effect, bubbles and holes exist in the through hole filled with the conductive metal material, and the lead bonding pad, the conductive metal material and the conductive metal pin cannot be fully contacted or even are not contacted at all; (2) although the purpose of annealing is to sinter the conductive metal material, so that the lead pad, the conductive metal material and the conductive metal pin can be fixedly connected and form good electrical connection, the conductive metal material can generate thermal deformation and volatile bubbles in the actual sintering process, so that the volume of the conductive metal material after annealing is reduced, the bubbles exist inside the conductive metal material, and even the lead pad, the conductive metal material and the conductive metal pin are disconnected due to the fact that the thermal expansion coefficients of different materials are inconsistent. Due to the above two problems, the success rate of actually obtaining a package structure is not high.

Chinese patent CN109781334A discloses a leadless package structure of piezoresistive sensor, in which the conductive paste (composed of silver, glass, organic binder and solvent) has a problem of generating thermal stress after sintering and curing, and in order to make the conductive paste after sintering and curing stably function as a connection structure, noble metal gold is further used as a transition layer, and the thermal stress is reduced by utilizing the good ductility of gold. However, the transition layer cannot solve the problems of thermal deformation and volatile bubbles generated in the actual sintering and curing process of the conductive paste. In addition, the size of the through hole through which the valve pin penetrates still needs to be limited to a small range, so the reliability of the connection structure is still affected by the micro-porous effect. Meanwhile, PbO-ZnO-B is also used in the patent₂O₃System-based glass paste formationThe softening point of the glass system can be adjusted according to the lead content, and can be in PbO-ZnO-B according to the requirement₂O₃Based on the addition of low expansion coefficient and negative expansion materials, e.g. PbTiO₃Cordierite, eucryptite, spodumene, quartz glass and the like form the composite glass slurry, the thermal expansion coefficient is adjusted, and the chemical stability and the mechanical strength are improved. However, the slurry has high viscosity, and the application mode and range are limited.

Disclosure of Invention

The invention provides a leadless packaging structure and a leadless packaging method of a high-temperature-resistant sensor, and aims to solve the technical problems of the existing high-temperature-resistant sensor packaging structure.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a leadless packaging structure of high temperature resistant sensor, this leadless packaging structure includes sensor chip, is used for supporting sensor chip's sensor housing and sets up the metal pin on sensor housing, the metal pin passes through the high temperature resistant conducting layer and links to each other with sensor chip's metal electrode, and this metal electrode is external on sensor housing surface or place sensor housing in.

Preferably, the sensor housing comprises a substrate and a chip packaging groove arranged on the substrate, the sensor chip is connected with the sensor housing through a sealing layer arranged at the bottom of the chip packaging groove, and the sensor chip is flush with the surface of the sensor housing.

Preferably, the sealing layer is formed by curing a high temperature resistant adhesive applied to the bottom of the chip package socket.

Preferably, the high-temperature-resistant adhesive comprises PbO-ZnO-B₂O₃The thermal expansion coefficient of the sealing layer of the glass paste of the system is between that of the sensor shell and that of the sensor chip.

Preferably, the sensor housing further comprises a channel disposed on the substrate, and the channel is connected to the bottom of the chip packaging groove.

Preferably, the sensor housing further includes a through hole disposed on the substrate, and a conductive sealing block is disposed in the through hole and filled between a portion of the metal pin located in the through hole and an inner wall of the through hole.

Preferably, the conductive sealing block is formed by curing a conductive glass paste injected into the inner space of the sensor housing along the through hole to bond a portion of the metal pin located in the through hole (bond the portion to the sensor housing).

Preferably, the conductive glass paste comprises PbO-ZnO-B as a component₂O₃Glass paste of the system and a nano conductive material.

Preferably, the base body is columnar, the chip packaging groove is formed in one end face of the base body, one end of the through hole is located in the other end face of the base body, and the other end of the through hole extends to the end face of the base body, wherein the chip packaging groove is formed in the end face of the base body.

Preferably, the through hole of the sensor shell is connected with the bottom of the chip packaging groove, and the high-temperature-resistant conducting layer is arranged between the metal pin and the metal electrode of the sensor chip in a superposition mode (namely the metal electrode is internally arranged); or the through hole of the sensor shell is arranged outside the chip packaging groove at the position on the end face of the base body, and the high-temperature-resistant conducting layer is arranged between the metal pin and the metal electrode of the sensor chip in a direct writing mode (namely the metal electrode is arranged externally).

Preferably, the high temperature conductive layer is formed by coating and curing a modified slurry containing a binder, a high temperature antioxidant and a nano conductive material (i.e., the binder is modified by the high temperature antioxidant and the nano conductive material), or the high temperature conductive layer is formed by coating and curing a modified slurry containing a binder, a high temperature antioxidant, a toughening agent and a nano conductive material (i.e., the binder is modified by the high temperature antioxidant, the toughening agent and the nano conductive material).

Preferably, the component of the adhesive comprises PbO-ZnO-B₂O₃The glass paste, i.e., the adhesive, of the system may be the above-mentioned high-temperature-resistant adhesive.

Preferably, the sensor housing further comprises an annular groove provided on a side surface of the base body.

A leadless packaging method of a high-temperature-resistant sensor comprises the following steps:

1) processing a chip packaging groove and a through hole on a substrate to obtain a sensor shell;

2) respectively and correspondingly bonding the metal pin and the sensor chip with the sensor shell through the through hole and the chip packaging groove, and then curing, and forming a high-temperature-resistant conducting layer which simultaneously covers the metal pin and the metal electrode of the sensor chip by using preset slurry (such as the modified slurry) which stretches across two sides of the junction position of the sensor shell and the sensor chip in the curing process to obtain a high-temperature-resistant sensor leadless packaging structure with an external metal electrode;

or, the metal pin is bonded with the sensor shell through the through hole, and before the sensor chip is bonded with the sensor shell through the chip packaging groove, slurry for forming the high-temperature-resistant conductive layer (for example, slurry identical to the preset slurry) is placed into the chip packaging groove, so that the metal pin and the metal electrode of the sensor chip are butted with the high-temperature-resistant conductive layer through curing, and the high-temperature-resistant sensor leadless packaging structure with the built-in metal electrode is obtained.

Preferably, the step 1) further comprises the following steps: and processing a cavity channel connected with the bottom of the chip packaging groove on the substrate.

Preferably, in the step 2), the conductive glass paste is injected into the through hole, and a gap between a part of the metal pin located in the through hole and the inner wall of the through hole is filled with the conductive glass paste, so that the metal pin is bonded to the sensor housing.

Preferably, in the step 2), the high-temperature-resistant adhesive is applied to a certain area of the bottom of the chip packaging groove (when the end surfaces of the through holes are located at the bottom of the chip packaging groove, since a high-temperature-resistant conductive layer needs to be formed in the area where the end surfaces are located, the high-temperature-resistant adhesive is applied to the bottom surface of the chip packaging groove except for the area; when the end face of the through hole is positioned outside the chip packaging groove, the bottom surface of the chip packaging groove is coated; the connecting part of the cavity channel and the bottom of the chip packaging groove is not coated), the sensor chip is placed into the chip packaging groove and is contacted with the coated high-temperature-resistant adhesive until the sensor chip is flush with the surface of the sensor shell, and therefore the sensor chip is bonded on the sensor shell.

The invention has the beneficial effects that:

in the high-temperature-resistant sensor packaging structure provided by the invention, the leadless packaging is realized by introducing the conducting layer which accords with the temperature grade of the sensor application, the reliability of the electric connection between the metal pin in the packaging structure and the metal electrode of the sensor chip is improved, and the defect of the existing packaging structure in the aspect of thermal stability is fundamentally overcome; meanwhile, the packaging mode of the sensor chip is flexible, the process difficulty of the packaging method is low, and the yield is high.

Furthermore, the sensor chip and the sensor shell are packaged in a flush mode, for the pressure sensor, the sensor chip is directly contacted with a measured high-temperature medium, the attenuation influence of a tube cavity effect on the dynamic performance of the sensor is avoided, the problems of response time lag and frequency distortion caused by the tube cavity effect are solved, and the sensor has higher response speed and higher resonant frequency.

Furthermore, the packaging materials directly connected with the sensor chip are few in types (only a few materials with the same glass paste component, such as a sensor shell material, cured high-temperature-resistant adhesive glue and the like are involved), so that the thermal expansion coefficients of the packaging materials and the sensor chip material are easy to match (the thermal expansion coefficients of the packaging materials and the sensor chip material are very close), and the possibility of thermal stress mismatch between heterogeneous materials is reduced; meanwhile, the packaging can be completed through one-time curing, and the process steps are simplified.

Furthermore, the thermal expansion coefficient of the high-temperature resistant adhesive after curing is between that of the traditional sensor shell and the sensor chip, so that the internal thermal expansion stress between the sensor shell and the sensor chip can be effectively relaxed, and the high-temperature stability and the thermal stress damage resistance of the sensor chip are improved.

Further, the invention takes the cavity (such as a channel structure and the like) at the bottom of the chip packaging groove and the through hole for adhering the metal pin as a stress relief structure of the sensor shell for thermal expansion, and reduces the internal stress caused by the thermal expansion difference between the sensor shell and the sensor chip.

Furthermore, the through hole arrangement mode adopted by the invention (especially when the end face of the through hole is positioned outside the chip packaging groove) is beneficial to increasing the aperture of the through hole, so that the metal pin can be more reliably fixed by using the packaging material (such as cured conductive glass paste) based on the glass paste with stronger viscosity.

Drawings

FIG. 1 is a schematic view of the entire structure (a) of the refractory sensor package and its longitudinal structure (b) in example 1;

FIG. 2 is a schematic view of a sensor housing (a) and its longitudinal sectional structure (b) inembodiment 1;

FIG. 3 is a schematic view of a metal lead in example 1;

FIG. 4-1 is a schematic view of a sensor chip (a) and its longitudinal sectional structure (b) in example 1;

FIG. 4-2 is a schematic diagram showing the shape and size matching between the cured high temperature resistant adhesive (a) and the backside (b) of the sensor chip in example 1;

fig. 5 is a schematic view of the whole structure (a) and the sensor housing (b) of the refractory sensor package ofembodiment 2;

fig. 6 is a schematic view of a package structure of a metal pin, conductive glass paste (a) and a direct-write conductive silver paste (b) inembodiment 2;

fig. 7 is a schematic view of a package structure of the high temperature resistant adhesive (a) and the sensor chip (b) inembodiment 2;

fig. 8 is a schematic view of a state that the conductive glass paste is injected into the circular channel (the dark color region is the package structure after the conductive glass paste is cured, i.e. the conductive sealing block); wherein: (a) example 1, (b) example 2;

in the figure: 1-a sensor housing; 2-metal pins; 3-a conductive sealing block; 4-a conductive layer; 5-a sensor chip; 6-sealing layer; 101-a through hole; 102-chip package slot; 103-lumen tract; 104-an annular groove; 501-a metal electrode; 502-cavities; 503-metal wires; 504-semiconductor sensitive resistance.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. The examples are given solely for the purpose of illustration and are not intended to limit the scope of the invention.

Aiming at the problems existing in the prior leadless package (especially for the package of a high temperature resistant sensor with the grade of more than 600 ℃) when a conductive metal material is poured and sintered into a fine package through hole, such as high operation difficulty and low yield (due to air resistance and pore effect inside a micropore, the package through hole is difficult to be filled with the conductive metal material, and a pore structure is easy to generate inside the conductive metal material in the curing process, and finally, a metal pin can not be well electrically connected with a lead pad on a sensor chip); the invention provides a leadless packaging structure of a high-temperature-resistant sensor, in the packaging of the high-temperature-resistant sensor, on one hand, the electric connection packaging of a metal pin and a metal electrode of a sensor chip is carried out in modes of direct writing of conductive silver paste and the like, and on the other hand, the sensor chip and a sensor shell are packaged in a flush mode through high-temperature-resistant adhesive glue, so that the packaging success rate of the high-temperature-resistant sensor is improved, and the packaging structure is stable and reliable, the packaging process is simple to operate, and the leadless packaging structure has strong industrial application value.

Example 1

As shown in fig. 1, the overall package structure of the high temperature sensor includes asensor housing 1, ametal pin 2, and asensor chip 5. A part of themetal pin 2 is fixed inside thesensor shell 1 through aconductive sealing block 3 formed by cured conductive glass slurry, and thesensor chip 5 is fixed on the upper end face of thesensor shell 1 in a embedding manner through asealing layer 6 formed by cured high-temperature-resistant adhesive glue; wherein,sensor chip 5 is openly up tometal pin 2's upper end, the electrically conductive glass thick liquids of solidification,sensor chip 5's front all flushes withsensor housing 1's up end, andmetal pin 2's lower extreme stretches out tosensor housing 1's lower extreme off-plate, andsensor chip 5's the back is relative with the passageway or the inner chamber structure that are locatedsensor housing 1 inside. High-temperature-resistant conducting layers 4 which are formed by curing direct-writing conductive silver paste and are continuously distributed in a strip shape are attached to the junction positions and the corresponding areas on two sides of the front surface of thesensor shell 1 and the front surface of thesensor chip 5, and a circuit structure on the front surface of thesensor chip 5 is connected with the upper ends of themetal pins 2 and the cured conductive glass paste through the high-temperature-resistant conducting layers 4.

As shown in fig. 2, thesensor housing 1 is formed by processing a cylindrical base body, and a circular throughhole 101, achip package groove 102, a chip packagegroove bottom channel 103 and anannular groove 104 are specifically processed on the base body.

Thechip packaging groove 102 is located in the middle of the upper end face of thesensor shell 1 and is mainly used for placing thesensor chip 5, the length and width of the chip packaging groove 102 (thechip packaging groove 102 is rectangular in fig. 2 a) or the diameter of thechip packaging groove 102 is matched with thesensor chip 5, the edge of thesensor chip 5 can be in close contact with the side wall of thechip packaging groove 102 after thesensor chip 5 is installed, the depth of thechip packaging groove 102 is slightly larger than the thickness of thesensor chip 5, a space is reserved for coating high-temperature-resistant adhesive with certain thickness at the bottom of thechip packaging groove 102, and the front face of thesensor chip 5 can be flush with the upper end face of thesensor shell 1.

Thechannel 103 is located below the bottom of thechip packaging groove 102 and is communicated with thechip packaging groove 102. The main functions of thecavity 103 are: (1) as a stress relief structure for thermal expansion of thesensor housing 1, thermal stress transmitted to thesensor chip 5 is reduced. (2) For the pressure sensor, if thechannel 103 directly penetrates the lower end surface of thesensor housing 1 and communicates with the outside (as shown in fig. 2b, that is, a channel structure is adopted), the corresponding pressure sensor can be used as a gauge pressure sensor, and if thechannel 103 does not penetrate the lower end surface of the sensor housing 1 (that is, an inner cavity structure is adopted), the corresponding pressure sensor can be used as an absolute pressure sensor through vacuum packaging.

The circular throughhole 101 completely penetrates through the upper end surface and the lower end surface of thesensor shell 1, and the through hole is mainly used for installing ametal pin 2 of the sensor; the number and relative positions of the circular throughholes 101 of thesensor housing 1 are generally determined according to the circuit structure of the front surface of thesensor chip 5, for example, in fig. 2a, the 5 circular throughholes 101 are arranged in two rows at intervals, and the arrangement positions of the circular throughholes 101 on the end surface of thesensor housing 1 are all located outside thechip packaging groove 102.

The function of theannular groove 104 includes: (1) the annular sealing ring is placed so that after the sensor is installed in a tested pipeline, a good sealing effect is formed between the sensor and the inner wall of the pipeline, and the detection accuracy is guaranteed; (2) the sensor is fixed as a positioning clamping groove.

The up end and the lower terminal surface ofsensor housing 1 do not have edges and corners (for example, realize through the edge machining radius angle at the upper and lower terminal surface of base member), avoid sharp-pointed right angle to draw on the one hand and hinder people or other objects, and on the other hand, when pressure sensor used in some pipe, chamber, the cylindric structure of taking the radius angle is favorable to the flow and the outward diffusion of air current, liquid stream, can not produce the swirl because of there being sharp-pointed right angle, influences actual measurement precision.

It should be noted that when the materials of thesensor housing 1 and thesensor chip 5 are selected, materials having the same or similar thermal expansion coefficients are selected, so that thermal expansion matching under a high-temperature environment is realized, and small thermal stress inside the sensor and good high-temperature stability of the sensor are ensured. For example, thesensor housing 1 has a thermal expansion coefficient of 4.1 × 10^-6AlN, an insulating material at/° C, and a thermal expansion coefficient of 3.7X 10 for manufacturing the MEMS chip used for thesensor chip 5^-6SiC material/° c.

As shown in fig. 3, themetal pins 2 are generally in the form of cylindrical slender bar structures (also called metal pins), and the specific number and relative positions thereof are consistent with the number and relative positions of the circular throughholes 101 provided in thesensor housing 1. Namely, ametal pin 2 is fixedly installed in a circular throughhole 101 by using aconductive sealing block 3 formed by curing conductive glass paste.

As shown in fig. 4-1 and 4-2, thesensor chip 5 is an MEMS miniaturized chip processed by a micro-nano manufacturing process. For example, in the case of thesensor chip 5 shown in fig. 4-1a, the front side of the circuit structure includes 5metal electrodes 501, and one end of themetal wire 503 is tightly connected to themetal electrodes 501, and the other end is tightly connected to the semiconductorsensitive resistor 504. If thesensor chip 5 is a pressure sensor chip, acavity 502 is formed on the back surface of the chip, the shape of thecavity 502 may be rectangular (including square), circular (fig. 4-2b), or other shapes, and the size of thecavity 502 and the relative position between the cavity and the semiconductorsensitive resistor 504 are determined according to the arrangement rule of the pressure sensor sensitive films and the sensitive resistors. If thesensor chip 5 is a vibrating sensor chip, the back side of the chip should be correspondingly machined with mass and cantilever structures. The number and the position of themetal electrodes 501 and the semiconductorsensitive resistors 504 on the front surface of thesensor chip 5 can be changed according to actual needs. The number and the positions of the circular throughholes 101 located outside thesensor chip 5 can be determined according to the number and the positions of themetal electrodes 501 on the front surface of thesensor chip 5. In addition, when thecavity 502 is formed in the back surface of thesensor chip 5, thecavity 103 located below the bottom of thechip packaging groove 102 is opposite to the back surface of thesensor chip 5, and the opening at the upper end of thecavity 103 is aligned to the opening of thecavity 502 through matching, so that the shape and the size of the opening are consistent, thechip packaging groove 102 is used for stably supporting the area of the back surface of thesensor chip 5 except the area corresponding to thecavity 502, the reliability of the sensor packaging structure is improved, only the area corresponding to thecavity 502 on thesensor chip 5 is movable, and other areas are fixed, so that thesensor chip 5 can perform measurement according to a preset theoretical state, and the measurement accuracy is ensured.

The high-temperature-resistant adhesive is a high-temperature adhesive and has good electrical insulation performance at high temperature. The high-temperature resistant adhesive is PbO-ZnO-B₂O₃The system is a glass paste mainly, except that PbO-ZnO-B is formed₂O₃The components of the system can also be mixed with lead titanate (PbTiO)₃) Cordierite, eucryptite, spodumene, quartz glass (SiO)₂) Is constituted as a component.

With PbO-ZnO-B₂O₃The formula of the glass slurry (namely the high-temperature resistant adhesive) mainly comprises the following components in percentage by mass:

①PbO：73％～77％

②B₂O₃：7％～13％

③ZnO：8％～13％

④PbTiO₃cordierite, eucryptite, spodumene, quartz glass: 0 to 5 percent.

The high-temperature resistant adhesive needs to be cured at high temperature through sintering to form asealing layer 6, and the specific use description is as follows:

1) coating high-temperature-resistant adhesive glue on the bottom of thechip packaging groove 102; in addition to controlling the coating thickness, it should be noted that the refractory adhesive is applied to form a complete sealing ring between the backside of the sensor chip and the bottom of the chip packaging groove, and cannot enter into thecavity 502 on the backside of thesensor chip 5, so as to avoid affecting the movable structures (such as sensitive film, mass, etc.) inside thesensor chip 5, that is, the refractory adhesive applied to the bottom of thechip packaging groove 102 should have a shape and size matching the shape and size of the backside of thesensor chip 5.

2) Curing

Raising the temperature from room temperature to 270 ℃ at the speed of 2 ℃/min, and keeping the temperature for 25 minutes; then uniformly raising the temperature to 550 ℃ within 135 minutes, and keeping the temperature for 5 minutes; then uniformly reducing the temperature to 540 ℃ within 10 minutes, and keeping the temperature for 20 minutes; then reducing the temperature from 540 ℃ to 495 ℃ within 20 minutes, and keeping the temperature for 20 minutes; then reducing the temperature from 495 ℃ to 455 ℃ within 20 minutes, and keeping the temperature for 20 minutes; then the temperature was decreased to room temperature at a rate of 2 deg.C/min.

The procedure is adopted to sinter the coated high-temperature-resistant adhesive, so that thesealing layer 6 obtained by sintering has no quality defects such as holes, cracks and the like, and the sintering strength and compactness are ensured.

After the high-temperature resistant adhesive is cured, the thermal expansion coefficient of the high-temperature resistant adhesive is between that of thesensor shell 1 and that of the sensor chip 5 (namely 3.7 multiplied by 10)^-6From/° C to 4.1X 10^-6Between/° c), and the thermal expansion coefficients of the three are very close, so that the back surface of thesensor chip 5 can be tightly fixed in thechip packaging groove 102 of thesensor housing 1, and the bonding and sealing effects are achieved; can also be used as a thermal expansion transition layerAnd the thermal expansion internal stress between thesensor shell 1 and thesensor chip 5 is relaxed, and the high-temperature stability and the thermal stress damage resistance of the sensor chip are improved.

The conductive glass paste is high-temperature resistant conductive paste obtained through blending, namely the conductive glass paste is formed by further mixing nano conductive silver powder on the basis of the components contained in the high-temperature resistant adhesive, and the mass fraction of the mixed nano conductive silver powder can be optimized according to the actual conductivity of the conductive glass paste after curing.

The specific use of the conductive glass paste is as follows:

1) filling in

And injecting conductive glass slurry into the circular through hole of the sensor shell by using a needle tube injector, and filling a gap between the part of the metal pin placed in the through hole and the inner wall of the through hole.

2) High temperature curing

The sintering procedure was referenced to the high temperature resistant bond paste described above.

The conductive glass paste after curing (i.e., the conductive sealing block 3) has the following main characteristics: (1) the high-temperature-resistant rubber has the characteristic of high temperature resistance, and is good in stability and not easy to denature when used in a high-temperature environment for a long time; (2) the conductive film has conductivity, low resistance value and small degree of change of the resistance value along with temperature change; (3) coefficient of thermal expansion of 3.7X 10^-6From/° C to 4.1X 10^-6The temperature is lower than the temperature of the sensor shell, and the temperature is lower than the temperature of the sensor shell; (4) the bonding nature is strong, the adhesion is good, can firmly fix metal pin in the circular through-hole of sensor housing.

The direct-writing conductive silver paste is a multi-component mixed paste composed of the high-temperature-resistant adhesive and a modifier (including not only nano conductive silver powder, but also components such as a toughness agent like micro-nano metal fibers, a high-temperature antioxidant like ferric oxide powder and the like). Forming physical connection between themetal electrode 501 on the front surface of thesensor chip 5 and the upper end (flush with the upper end surface of the sensor shell 1) of the correspondingmetal pin 2 by 3D printing or spraying the direct-writing conductive silver paste, and then performing high-temperature curing on the direct-writing conductive silver paste forming the physical connection (referring to a sintering program)The high-temperature resistant adhesive), a functionalized structure layer can be formed, wherein the functionalized structure layer is tightly adhered to a plane which is formed by the upper end of themetal pin 2, the correspondingmetal electrode 501, the upper end surface of thesensor shell 1 positioned between the metal pin and the functionalized structure layer, the conductive glass slurry (the upper end of the conductive sealing block 3) solidified on the periphery of themetal pin 2 and the corresponding area on the front surface of thesensor chip 5. The functional structure layer has high temperature resistance and low resistance value conductive property (also called as high temperature resistance conductive layer 4), and has a thermal expansion coefficient similar to that of the sensor shell and the chip material (namely 3.7 multiplied by 10)^-6From/° C to 4.1X 10^-6Between/° c), while avoiding the problem of oxidation failure (conductivity loss due to surface oxidation) occurring at high temperature and the problem of breakage occurring at the interface of the sensor housing and the sensor chip, so that a stable electrical connection can be formed between themetal pin 2 and themetal electrode 501 on the front surface of thesensor chip 5.

In the high-temperature working environment of the sensor, the high-temperature-resistantconductive layer 4 formed by curing the direct-writing conductive silver paste has good conductivity, toughness and high-temperature oxidation resistance, and provides stable and reliable electric connection between thesensor chip 5 and an external circuit connected to themetal pin 2. Meanwhile, theconductive sealing block 3 formed by curing the conductive glass paste adopted by the invention has an additional function of ensuring reliable electrical connection between themetal electrode 501 on the front surface of thesensor chip 5 and themetal pin 2. Although themetal pin 2 and themetal electrode 501 of thesensor chip 5 are indirectly connected through the cured direct-writing conductive silver paste, even if an open circuit occurs between the cured direct-writing conductive silver paste and themetal pin 2, the electrical connection reliability of the sensor is not affected, because the glass paste used for bonding themetal pin 2 in the circular through hole is conductive after being cured, an electrical signal can be transmitted to the cured conductive glass paste through the cured direct-writing conductive silver paste and then transmitted to themetal pin 2.

The overall packaging structure of the high-temperature-resistant sensor of the embodiment can be obtained by adopting the following packaging process flow:

1) processing sensor shell

Processing 1chip packaging groove 102 matched with the size and shape of thesensor chip 5 and 1 channel (as a chip packaging groove bottom cavity channel 103) extending from the bottom of thechip packaging groove 102 to the lower end face of the cylindrical substrate on the upper end face of the cylindrical substrate; referring to a circuit structure on the front surface of thesensor chip 5 which needs to be placed in thechip packaging groove 102, 5 circular throughholes 101 which have the same diameter, penetrate through the upper end surface and the lower end surface of the cylindrical substrate and are spaced from themetal electrode 501 on the front surface of thesensor chip 5 by a certain distance are processed on the cylindrical substrate; on the side of thecylindrical base 1annular groove 104 is machined.

2) Bonding sensor chip and metal pin

Inserting 5metal pins 2 into corresponding circular throughholes 101 of thesensor shell 1 processed in the step 1 (the upper ends of the 5 metal pins are flush with the upper end face of the sensor shell 1), and injecting conductive glass slurry into the circular throughholes 101 containing themetal pins 2 at the lower end face of thesensor shell 1, wherein the injection amount of the conductive glass slurry is based on the fact that the conductive glass slurry can fully contact themetal pins 2 and the circular through holes 101 (fig. 8 a); high-temperature-resistant adhesive glue is coated at the bottom of thechip packaging groove 102 of thesensor shell 1, then thesensor chip 5 is placed in the high-temperature-resistant adhesive glue, thesensor chip 5 is tightly embedded into thechip packaging groove 102, and the front surface of thesensor chip 5 is flush with the upper end surface of thesensor shell 1.

3) The direct-writing conductive silver paste is used to form physical connection between themetal electrode 501 on the front surface of thesensor chip 5 and the correspondingmetal pin 2 on the outer side.

4) Fixing the embeddedsensor chip 5 on the corresponding end face of thesensor shell 1 through high-temperature curing (namely, firmly fixing thesensor chip 5 in the chip packaging groove 102); theconductive sealing block 3 formed by high-temperature curing not only seals one end of the circular throughhole 101 close to thesensor chip 5, but also enables the cured conductive glass paste to be tightly and reliably combined with the metal pin 2 (so as to realize electric connection), and fixes themetal pin 2 in the circular through hole 101 (i.e. fixes themetal pin 2 and thesensor shell 1 together); the 5 flat high temperature resistantconductive layers 4 formed by the high temperature curing realize the electrical connection between themetal pin 2 and themetal electrode 501.

Example 2

Theabove embodiment 1 is directed to the sensor chip being relatively friendly to the working environment, for example, the chip is not directly contacted with moisture, dust or corrosive substances.Embodiment 2 is proposed in consideration of protecting the circuit structure on the front surface of the sensor chip with the package structure if the sensor chip operates in an environment containing moisture, dust, or corrosive substances.

As shown in fig. 5a, the main difference between the overall package structure of the high temperature sensor of this embodiment andembodiment 1 is: thesensor chip 5 is reversely buckled in thechip packaging groove 102, namely the back of thesensor chip 5 faces upwards, the arrangement positions of the circular throughholes 101 on the end face of thesensor shell 1 are all located inside thechip packaging groove 102, namely the upper ends of the circular throughholes 101 are also communicated with thechip packaging groove 102, and the positions of thegroove bottom cavities 103 are unchanged, namely thecavities 103 are surrounded in the middle of thesensor shell 1 by the circular throughholes 101.

The overall packaging structure of the high-temperature-resistant sensor of the embodiment can be obtained by adopting the following packaging process flow:

1) processing sensor shell

As shown in fig. 5b, 1chip package groove 102 matching the size and shape of thesensor chip 5 and 1 channel (as chip package groove bottom channel 103) extending from the bottom of thechip package groove 102 to the lower end face of the cylindrical substrate are processed on the upper end face of the cylindrical substrate; referring to a circuit structure on the front surface of thesensor chip 5 which needs to be placed in thechip packaging groove 102, 5 circular throughholes 101 which have the same diameter, penetrate through the cylindrical substrate and can be opposite to themetal electrode 501 of thesensor chip 5 are processed on the cylindrical substrate; on the side of thecylindrical base 1annular groove 104 is machined.

2) Adhesive metal pin

As shown in fig. 6a and 8b, themetal pin 2 is bonded in the circular through-hole 101 by the conductive glass paste according to step 2) of example 1.

3) As shown in fig. 6b, a direct-writing conductive silver paste is coated on the end surface of eachmetal lead 2 at the bottom of thechip packaging groove 102 and inside the edge of the corresponding circular through hole 101 (at the upper end of the conductive glass paste filling area).

4) As shown in fig. 7, a high temperature resistant adhesive is applied to the bottom of thechip packaging groove 102 except for the direct-writing conductive silver paste application area and the other area except the channel structure opening, and thesensor chip 5 is placed into thechip packaging groove 102 in such a manner that the back surface (with the cavity 502) faces upwards (thesensor chip 5 is inverted), and themetal electrodes 501 are respectively aligned with the direct-writing conductive silver paste application areas, so that thesensor chip 5 is tightly embedded into thechip packaging groove 102, and the front surface of thesensor chip 5 is flush with the upper end surface of thesensor housing 1.

5) After sintering, thesensor chip 5 and themetal pin 2 are firmly fixed on thesensor housing 1 along with the complete curing of the conductive glass paste in the circular throughhole 101, the direct-writing conductive silver paste in thechip packaging groove 102, and the high-temperature-resistant adhesive, and the high-temperature-resistantconductive layer 4 between themetal pin 2 and the opposite end of the metal electrode 501 (and the conductive sealing block 3) is formed.

The following are specifically mentioned: (1) the positions of eachmetal pin 2, theconductive sealing block 3 formed after the conductive glass paste is cured, the high-temperature-resistantconductive layer 4 formed after the direct-writing conductive silver paste is cured and themetal electrode 501 of thesensor chip 5 are in one-to-one correspondence and are positioned on the same axis, so that complete electric connection can be formed after the sensor is packaged; (2) the depth of thechip packaging groove 102, the coating thickness of the high-temperature-resistant adhesive and the direct-writing conductive silver paste and the thickness of thesensor chip 5 are matched, so that the back surface of the sensor chip is flush with the upper end surface of the sensor shell after the sensor is packaged.

The sensor chip flip-chip package adopted by the embodiment has the advantages that: (1) the circuit structure on the front side of thesensor chip 5 is effectively protected from being invaded by water vapor, dust and corrosive substances in the external environment, the service life of the sensor is long, and the environmental adaptability is strong; (2) for the pressure sensor, the measured medium applies pressure to the back of thesensor chip 5, so that the stability of the electric connection between themetal electrode 501 on the front surface of thesensor chip 5, theconductive sealing block 3 formed after the conductive glass slurry is cured and themetal pin 2 and the high-temperature-resistantconductive layer 4 formed after the direct-writing conductive silver slurry is cured can be effectively promoted, and the connection stability can be higher along with the long-time use of the sensor.

In a word, the high-temperature-resistant leadless packaging structure and the packaging process thereof solve the problem of reliability disintegration and even failure of the conventional metal lead bonding packaging technology in a high-temperature environment, simplify the packaging lead mode, have simple operation, high yield and high reliability in practical use, are suitable for batch production, have low cost and have high cost performance. Meanwhile, the invention improves the working stability and long-term reliability of the sensor in a high-temperature environment by selecting and simplifying the packaging material, and the sensor chip has the advantage of good dynamic response characteristic by adopting flush packaging.

Claims (10)

Translated fromChinese

1.一种耐高温传感器的无引线封装结构，其特征在于：该无引线封装结构包括传感器芯片(5)、用于支撑传感器芯片(5)的传感器壳体(1)以及设置在传感器壳体(1)上的金属引脚(2)，所述金属引脚(2)通过耐高温导电层(4)与传感器芯片(5)的金属电极(501)相连，该金属电极(501)外置在传感器壳体(1)表面或内置于传感器壳体(1)。1. A leadless package structure of a high temperature sensor, characterized in that: the leadless package structure comprises a sensor chip (5), a sensor housing (1) for supporting the sensor chip (5), and a sensor housing (1) arranged in the sensor housing The metal pin (2) on the (1), the metal pin (2) is connected to the metal electrode (501) of the sensor chip (5) through the high temperature resistant conductive layer (4), and the metal electrode (501) is externally located On the surface of the sensor housing (1) or built into the sensor housing (1).2.根据权利要求1所述一种耐高温传感器的无引线封装结构，其特征在于：所述传感器壳体(1)包括基体以及设置在基体上的芯片封装槽(102)，传感器芯片(5)通过设置在芯片封装槽(102)底部的封接层(6)与传感器壳体(1)相连，传感器芯片(5)与传感器壳体(1)的表面齐平。2 . The leadless package structure of a high temperature resistant sensor according to claim 1 , wherein the sensor housing ( 1 ) comprises a base body and a chip packaging groove ( 102 ) arranged on the base body, and the sensor chip ( 5 ). ) is connected to the sensor housing (1) through a sealing layer (6) arranged at the bottom of the chip packaging groove (102), and the sensor chip (5) is flush with the surface of the sensor housing (1).3.根据权利要求2所述一种耐高温传感器的无引线封装结构，其特征在于：所述封接层(6)是通过将涂敷在芯片封装槽(102)底部上的耐高温粘接胶固化后而形成的；耐高温粘接胶的组分包括PbO-ZnO-B₂O₃体系的玻璃浆料。3. A leadless package structure of a high temperature resistant sensor according to claim 2, characterized in that: the sealing layer (6) is made of a high temperature resistant adhesive coated on the bottom of the chip packaging groove (102). It is formed after the glue is cured; the components of the high temperature resistant adhesive include glass paste of the PbO-ZnO-B₂ O₃ system.4.根据权利要求2所述一种耐高温传感器的无引线封装结构，其特征在于：所述传感器壳体(1)还包括设置在基体上的腔道(103)，腔道(103)与芯片封装槽(102)的底部相连。4 . The leadless package structure of a high temperature resistant sensor according to claim 2 , wherein the sensor housing ( 1 ) further comprises a cavity ( 103 ) arranged on the base, and the cavity ( 103 ) is connected with the cavity ( 103 ). 5 . The bottoms of the chip packaging grooves (102) are connected.5.根据权利要求2或4所述一种耐高温传感器的无引线封装结构，其特征在于：所述传感器壳体还包括设置在基体上的通孔(101)，该通孔(101)内设置有导电封接块(3)，导电封接块(3)填充在金属引脚(2)位于通孔(101)内的部分与通孔(101)的内壁之间。5. The leadless package structure of a high temperature resistant sensor according to claim 2 or 4, characterized in that: the sensor housing further comprises a through hole (101) arranged on the base body, and the through hole (101) A conductive sealing block (3) is provided, and the conductive sealing block (3) is filled between the part of the metal pin (2) located in the through hole (101) and the inner wall of the through hole (101).6.根据权利要求5所述一种耐高温传感器的无引线封装结构，其特征在于：所述导电封接块(3)是通过将沿所述通孔(101)注入传感器壳体(1)内部空间的导电玻璃浆料进行固化后而形成的；导电玻璃浆料的组分包括PbO-ZnO-B₂O₃体系的玻璃浆料。6 . The leadless package structure of a high temperature resistant sensor according to claim 5 , wherein the conductive sealing block ( 3 ) is injected into the sensor housing ( 1 ) along the through hole ( 101 ). 7 . The conductive glass paste in the inner space is formed after curing; the components of the conductive glass paste include glass paste of PbO-ZnO-B₂ O₃ system.7.根据权利要求5所述一种耐高温传感器的无引线封装结构，其特征在于：所述基体为柱状，芯片封装槽(102)开设于基体的一个端面上，通孔(101)的一端位于基体的另一个端面上，通孔(101)的另一端延伸至开设有芯片封装槽(102)的基体端面。7 . The leadless package structure of a high temperature resistant sensor according to claim 5 , wherein the base body is columnar, the chip packaging groove (102) is opened on one end face of the base body, and one end of the through hole (101) is open. 8 . On the other end surface of the base body, the other end of the through hole (101) extends to the end surface of the base body where the chip packaging groove (102) is opened.8.根据权利要求7所述一种耐高温传感器的无引线封装结构，其特征在于：所述传感器壳体(1)的通孔(101)与芯片封装槽(102)的底部相连，耐高温导电层(4)以叠加的方式设置在金属引脚(2)与传感器芯片(5)的金属电极(501)之间；或者，所述传感器壳体(1)的通孔(101)在基体端面上的布置位置为位于芯片封装槽(102)外部，耐高温导电层(4)以直写的方式设置在金属引脚(2)与传感器芯片(5)的金属电极(501)之间；耐高温导电层(4)采用以PbO-ZnO-B₂O₃体系的玻璃浆料为主成分的改性浆料并经涂敷、固化而制成。8 . The leadless package structure of a high temperature resistant sensor according to claim 7 , wherein the through hole ( 101 ) of the sensor housing ( 1 ) is connected to the bottom of the chip packaging groove ( 102 ), and is resistant to high temperature. 9 . The conductive layer (4) is disposed between the metal pins (2) and the metal electrodes (501) of the sensor chip (5) in a superposed manner; alternatively, the through holes (101) of the sensor housing (1) are in the base body The arrangement position on the end face is outside the chip packaging groove (102), and the high temperature resistant conductive layer (4) is arranged between the metal pin (2) and the metal electrode (501) of the sensor chip (5) in a direct writing manner; The high-temperature-resistant conductive layer (4) is made by coating and curing a modified paste whose main component is a glass paste of a PbO-ZnO-B₂ O₃ system.9.根据权利要求7所述一种耐高温传感器的无引线封装结构，其特征在于：所述传感器壳体(1)还包括设置在基体的侧面上的环形凹槽(104)。9 . The leadless package structure of a high temperature resistant sensor according to claim 7 , wherein the sensor housing ( 1 ) further comprises an annular groove ( 104 ) arranged on the side surface of the base body. 10 .10.一种耐高温传感器的无引线封装方法，其特征在于：包括以下步骤：10. A leadless packaging method for a high temperature sensor, characterized in that: comprising the following steps:1)在基体上加工芯片封装槽(102)和通孔(101)，得到传感器壳体(1)；1) processing the chip packaging groove (102) and the through hole (101) on the base to obtain the sensor housing (1);2)将金属引脚(2)、传感器芯片(5)分别通过通孔(101)、芯片封装槽(102)与传感器壳体(1)对应粘接后进行固化，并在固化中利用横跨传感器壳体(1)与传感器芯片(5)交界位置两侧的预置浆料形成同时覆盖金属引脚(2)与传感器芯片(5)的金属电极(501)的耐高温导电层(4)，得到金属电极外置的耐高温传感器无引线封装结构；2) The metal pins (2) and the sensor chip (5) are respectively bonded to the sensor housing (1) through the through holes (101) and the chip packaging groove (102), respectively, and then cured. The preset paste on both sides of the interface of the sensor housing (1) and the sensor chip (5) forms a high temperature resistant conductive layer (4) which simultaneously covers the metal pins (2) and the metal electrodes (501) of the sensor chip (5). , to obtain a leadless package structure of a high temperature sensor with an external metal electrode;或者，将金属引脚(2)通过通孔(101)与传感器壳体(1)粘接，并在将传感器芯片(5)通过芯片封装槽(102)与传感器壳体(1)粘接前将用于形成耐高温导电层(4)的浆料置入芯片封装槽(102)内，从而通过固化同时使金属引脚(2)及传感器芯片(5)的金属电极(501)与耐高温导电层(4)对接，得到金属电极内置的耐高温传感器无引线封装结构。Alternatively, the metal pins (2) are bonded to the sensor housing (1) through the through holes (101), and before the sensor chip (5) is bonded to the sensor housing (1) through the chip packaging groove (102) The paste for forming the high-temperature-resistant conductive layer (4) is placed in the chip packaging groove (102), so that the metal pins (2) and the metal electrodes (501) of the sensor chip (5) can be simultaneously cured with the high-temperature-resistant paste. The conductive layers (4) are butted to obtain a leadless package structure of a high temperature sensor with built-in metal electrodes.

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