QFN encapsulating structure with anti-short-circuit functionTechnical field
The invention belongs to leadless packages technical field more particularly to a kind of QFN encapsulating structures with anti-short-circuit function.
Background technique
QFN is encapsulated in pcb board using very extensively, and the application of QFN encapsulation has greatly pushed the development of electronic technology.QFNEncapsulation has excellent hot property, and being primarily due to package bottom has large area heatsink welding, in order to effectively by heat from corePiece is transmitted on PCB, and the bottom PCB must design corresponding heat dissipation bonding pad and dissipating vias, and heat dissipation bonding pad providesReliable bonding area, dissipating vias provide sinking path.
The design of conventional QFN encapsulation in the pcb usually has the heat dissipation bonding pad of a large area, this heat dissipation bonding pad is usualGround connection, although this heat dissipation bonding pad can play the role of chip cooling, often due to pad is excessive, in patch (SMT) mistakeBrush tin excessively will lead to the short circuit phenomenon of this QFN encapsulation center big heat dissipation bonding pad and other small conductive welding disks in journey.In addition, as integrated antenna package is towards densification, highly integrated, high speed direction continuous development, encapsulating structure also faceFace receiving chip to generate heat and a series of security risks of bring.Therefore, how to develop a kind of with the resistance to of anti-short-circuit functionHeat-sealing assembling structure has great importance for the development of high performance electronics.
Summary of the invention
It is an object of that present invention to provide a kind of QFN encapsulating structure with anti-short-circuit function, which has goodAnti- short-circuit function, and the good stable structure of overall mechanical properties has very high reliability.
In order to achieve the above objectives, the technical solution adopted by the present invention is that: a kind of QFN with anti-short-circuit function encapsulates knotStructure, including heat dissipation bonding pad, chip and the conductive welding disk being located in epoxy insulator, the chip is located on heat dissipation bonding pad, and instituteIt states and is equipped with silver slurry layer between chip and heat dissipation bonding pad, be located at heat dissipation bonding pad periphery and be equipped with several conductive welding disks, the conductive welderingDisk is connected with chip by a lead；
The heat dissipation bonding pad is provided with separation trough far from the side of chip, and the separation groove width is 0.1 ~ 0.3mm, the separation troughHeat dissipation bonding pad is separated to form at least 2 pieces of pad monomers far from the side equal part of chip, is filled in the separation trough thermally conductive exhaustedEdge strip, several T-slots extended in heat dissipation bonding pad are provided in the separation groove groove wall, and the heat conductive insulating item is equipped with and fills outFill the T shape portion in T-slot；
The raw material of the epoxy insulator includes following parts by weight of component:
80 ~ 100 parts of epoxy resin,
45 ~ 60 parts of linear phenol-aldehyde resin,
15 ~ 20 parts of liquid nitrile rubber,
6 ~ 10 parts of methyl diphenylene diisocyanate,
3 ~ 8 parts of pyrocarbonic acid diethyl ester,
2 ~ 6.5 parts of phosphate dibenzyl ester,
60 ~ 90 parts of silicon powder,
3 ~ 8 parts of γ-methacryloxypropyl trimethoxy silane,
0.3 ~ 2 part of the fluoro- 2- aminoanisole of 5-,
2,4,6- tri- 0.5 ~ 4 part of (dimethylamino methyl) phenol,
2 ~ 5 parts of release agent,
10 ~ 25 parts of fire retardant.
Further improved technical solution is as follows in above-mentioned technical proposal:
1. in above scheme, the release agent is selected from least one of stearic acid, stearate or oxidized polyethylene wax.
2. in above scheme, the fire retardant is borate and/or molybdate.
3. in above scheme, the silicon powder is melting silicon powder.
4. in above scheme, the silicon powder D50 is 4 ~ 8 μm, the silicon powder D100 is 10 ~ 25 μm.
5. in above scheme, the heat conductive insulating thickness, which is less than, separates groove deep.
6. in above scheme, the area of the pad monomer is not less than 0.3*0.3mm2。
7. in above scheme, the spacing of the conductive welding disk and heat dissipation bonding pad is 0.3mm.
8. in above scheme, the conductive welding disk is T-block.
Due to the application of the above technical scheme, compared with the prior art, the invention has the following advantages:
1. the present invention has the QFN encapsulating structure of anti-short-circuit function, epoxy insulator formula is added in epoxy-resin systems15 ~ 20 parts of liquid nitrile rubber, it is used as curing accelerator using 0.5 ~ 4 part of 2,4,6- tri- (dimethylamino methyl) phenol, andIt is additionally added to 0.3 ~ 2 part of 3 ~ 8 parts of pyrocarbonic acid diethyl ester and the fluoro- 2- aminoanisole of 5-, improves the crosslink density of solidfied material,To enhance the overall mechanical properties of epoxy insulator, encapsulating structure stability has been effectively ensured.
2. the present invention has the QFN encapsulating structure of anti-short-circuit function, epoxy insulator formula is in epoxy resin 80 ~ 100Part, on the basis of 45 ~ 60 parts of linear phenol-aldehyde resin and 15 ~ 20 parts of liquid nitrile rubber, and be added to two isocyanide of diphenyl methane6 ~ 10 parts of acid esters and 2 ~ 6.5 parts of phosphate dibenzyl ester, resin obtained is under the premise of guaranteeing excellent mechanical performances, with excellentElegant heat resistance, glass transition temperature can meet the requirement of high-power high fever chip package up to 190 ~ 230 DEG C.
3, the present invention has the QFN encapsulating structure of anti-short-circuit function, opens on the heat dissipation bonding pad surface far from chip-sideIf separation trough, heat dissipation bonding pad is divided into far from a part of equal part of chip by least two pieces of pads by separation trough of different shapesMonomer, after being divided into multiple pad monomers, pad monomer is less than former heat dissipation bonding pad far from core far from the surface area of chip-sideThe surface area of piece side to reduce the usage amount of tin cream, and then effectively controls the short circuit between heat dissipation bonding pad and conductive welding diskPhenomenon；Meanwhile after being filled with upper heat conductive insulating item in separation trough, it is poor that separation slot part will not fill heat-conducting effectEpoxy insulation resin, the heat sinking function to guarantee heat dissipation bonding pad part is unaffected, and with the reduction of tin cream usage amount, moreover it is possible toReduce patch cost；In addition, heat conductive insulating item, when being filled into separation trough by way of injection molding, part resin is able to enterIn T-slot, the at T-shaped portion of shape is avoided to stabilize heat conductive insulating position using the clamping of T shape portion and T-slot due to injection moldingQuality problems or external force cause heat conductive insulating item to be detached from separation trough and influence its use.
Detailed description of the invention
Fig. 1 is the QFN package structure diagram that the present invention has anti-short-circuit function；
Fig. 2 is the enlarged drawing of part A in Fig. 1.
In the figures above: 1, heat dissipation bonding pad；11, separation trough；111, T-slot；12, heat conductive insulating item；121, T shape portion；13,Pad monomer；2, silver slurry layer；3, chip；4, conductive welding disk；5, lead；6, epoxy insulator.
Specific embodiment
The present invention will be further described below with reference to examples:
Embodiment 1 ~ 4: a kind of QFN encapsulating structure with anti-short-circuit function, including the heat dissipation bonding pad being located in epoxy insulator 61, chip 3 and conductive welding disk 4, the chip 3 are located on heat dissipation bonding pad 1, and silver is equipped between the chip 3 and heat dissipation bonding pad 1Pulp layer 2 is located at 1 periphery of heat dissipation bonding pad equipped with several conductive welding disks 4, the conductive welding disk 4 and chip 3 and passes through a lead 5 companyIt connects；
The heat dissipation bonding pad 1 is provided with separation trough 11 far from the side of chip 3, and 11 width of separation trough is 0.1 ~ 0.3mm, describedHeat dissipation bonding pad 1 is separated to form at least 2 pieces of pad monomers 13, the separation trough 11 far from the side equal part of chip 3 by separation trough 11In be filled with heat conductive insulating item 12, be provided with several T-slots 111 extended in heat dissipation bonding pad 1 on 11 cell wall of separation trough,The heat conductive insulating item 12 is equipped with the T shape portion 121 being filled in T-slot 111；
Above-mentioned 12 thickness of heat conductive insulating item is less than 11 groove depth of separation trough；
The area of above-mentioned pad monomer 13 is not less than 0.3*0.3mm2；
The spacing of above-mentioned conductive welding disk 4 and heat dissipation bonding pad 1 is 0.3mm；
Above-mentioned conductive welding disk 4 is T-block.
The raw material of above-mentioned epoxy insulator 6 includes following parts by weight of component:
Table 1
| Component | Embodiment 1 | Embodiment 2 | Embodiment 3 | Embodiment 4 |
| Epoxy resin | 80 | 85 | 90 | 100 |
| Linear phenol-aldehyde resin | 50 | 60 | 45 | 55 |
| Liquid nitrile rubber | 20 | 15 | 16 | 18 |
| Methyl diphenylene diisocyanate | 6 | 8 | 9 | 10 |
| Pyrocarbonic acid diethyl ester | 7 | 3 | 5 | 8 |
| Phosphate dibenzyl ester | 6.5 | 3 | 5 | 2 |
| Silicon powder | 60 | 90 | 80 | 70 |
| γ-methacryloxypropyl trimethoxy silane | 6 | 4 | 3 | 8 |
| The fluoro- 2- aminoanisole of 5- | 0.3 | 1.5 | 2 | 1 |
| 2,4,6- tri- (dimethylamino methyl) phenol | 4 | 3 | 1.5 | 0.5 |
| Release agent | 3 | 4 | 2 | 5 |
| Fire retardant | 25 | 20 | 15 | 10 |
Above-mentioned silicon powder is melting silicon powder, and above-mentioned silicon powder D50 is 4 ~ 8 μm, and above-mentioned silicon powder D100 is 10 ~ 25 μm.
Release agent in embodiment 1 is stearic acid, and fire retardant is borate；Release agent in embodiment 2 is stearate,Fire retardant is borate；Release agent in embodiment 3 is oxidized polyethylene wax, and fire retardant is molybdate；Demoulding in embodiment 4Agent is the mixture of stearic acid and oxidized polyethylene wax, and fire retardant is molybdate.
The method for preparing raw material of above-mentioned epoxy insulator 6 the following steps are included:
S1. first by 10 ~ 25 parts of 60 ~ 90 parts of silicon powder and fire retardant and γ-methacryloxypropyl trimethoxy silane 3 ~8 parts are uniformly mixed, and are surface-treated；
S2. 80 ~ 100 parts of epoxy resin, 45 ~ 60 parts of linear phenol-aldehyde resin, 15 ~ 20 parts of liquid nitrile rubber, diphenyl are added6 ~ 10 parts of methane diisocyanate, 3 ~ 8 parts of pyrocarbonic acid diethyl ester, 2 ~ 6.5 parts of phosphate dibenzyl ester, the fluoro- 2- aminoanisole 0.3 of 5-~ 2 parts, 2,4,6- tri- 0.5 ~ 4 part of (dimethylamino methyl) phenol and 2 ~ 5 parts of release agent are uniformly mixed；
S3. mixture is kneaded 3 ~ 5 minutes in 90 ~ 110 DEG C, is pulverized and sieved after product is cooling.
Comparative example 1 ~ 3: a kind of epoxy insulator, raw material include following parts by weight of component:
Table 2
| Component | Comparative example 1 | Comparative example 2 | Comparative example 3 |
| Epoxy resin | 90 | 80 | 100 |
| Linear phenol-aldehyde resin | 60 | 45 | 55 |
| Liquid nitrile rubber | 20 | 5 | 16 |
| Methyl diphenylene diisocyanate | 2 | 6 | 3 |
| Pyrocarbonic acid diethyl ester | 8 | 3 | - |
| Phosphate dibenzyl ester | 6.5 | - | - |
| Silicon powder | 60 | 90 | 80 |
| γ-methacryloxypropyl trimethoxy silane | 5 | 3 | 8 |
| The fluoro- 2- aminoanisole of 5- | - | 1.5 | 2 |
| 2,4,6- tri- (dimethylamino methyl) phenol | 4 | 0.5 | 2 |
| Release agent | 4 | 2 | 5 |
| Release agent | 25 | 10 | 15 |
Above-mentioned silicon powder is melting silicon powder, and above-mentioned silicon powder D50 is 4 ~ 8 μm, and above-mentioned silicon powder D100 is 10 ~ 25 μm.
Release agent in comparative example 1 is stearic acid, and fire retardant is borate；Release agent in comparative example 2 is stearate,Fire retardant is borate；Release agent in comparative example 3 is oxidized polyethylene wax, and fire retardant is molybdate.
The same embodiment of process of preparing.
The performance of epoxy insulator made from above-described embodiment 1 ~ 4 and comparative example 1 ~ 3 is as shown in table 3:
Table 3
In each embodiment and comparative example, the condition of molding of epoxy insulator is equal are as follows: and 180 DEG C of mold temperature, injection pressure 700kg/cm2, curing time 2min.
As shown in the evaluation result of table 3, epoxy insulator either overall mechanical properties in each embodiment or heat-resistingPerformance is superior to each comparative example, for that can guarantee encapsulating structure stability in QFN encapsulating structure, and can satisfy high-power heightThe requirement of euthermic chip encapsulation.
The above embodiments merely illustrate the technical concept and features of the present invention, and its object is to allow person skilled in the artScholar cans understand the content of the present invention and implement it accordingly, and it is not intended to limit the scope of the present invention.It is all according to the present inventionEquivalent change or modification made by Spirit Essence, should be covered by the protection scope of the present invention.