CN102530839A - Manufacturing method of capacitive micro-electromechanical ultrasonic sensor with bent focusing - Google Patents

Abstract

The invention discloses a manufacturing method of a capacitive micro-electromechanical ultrasonic sensor with bent focusing. The method comprises the following steps: manufacturing a device layer and a base which constitute a capacitive micro-electromechanical sensor into a whole, placing a gasket between the base and substrate of the sensor; applying forces to the sensor on which the gasket is placed so as to bend the sensor until a required bend degree is achieved; and maintaining the bend degree of the sensor. According to the other scheme, the method comprises the following steps: forming a hollow cavity at the base and utilizing the boundary wall of the hollow cavity as the gasket; placing another substrate with certain thickness on the gasket so as to cover the hollow cavity of the base; manufacturing the capacitive micro-electromechanical ultrasonic sensor on the substrate; and bending the sensor until the required bend degree is achieved. The technical scheme provided by the invention has the beneficial effects of simple method, high precision, low cost and suitability for large scale production.

Description

The preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band

Technical field

The present invention relates to the electronic devices and components field, especially sonac.

Background technology

The micro electronmechanical sonac of condenser type is a kind of electrostatic transducer that extensive use is arranged.Sonac can be worked in the multiple media such as solid and gas at liquid.Sonac has been applied in medicine diagnosis and treatment, the not damaged testing of materials, and sonar, communication, proximity transducer, flow measurement, real-time technology controlling and process is in the fields such as ultrasonic microscope.

The sensor made from piezoelectric ceramics (PZT) technology with extensive use compares, and the micro electronmechanical sonac of condenser type is in manufacture craft, and all there is very big advantage aspects such as spectral bandwidth and operating temperature.For example, do sensor array, need cut each array element respectively with traditional manufacture craft.So take time and effort, cost is high.And the cutting method precision is limited, so do high frequency, the sensor array of two some special geometry of peacekeeping is difficulty especially.The micro electronmechanical sonac of condenser type is to process with semiconductor technology, so a lot of sensor can be made in batch together.The precision of semiconductor fabrication process enough satisfies the demand of the micro electronmechanical sonac of condenser type.The micro electronmechanical ultrasonic sensor array of condenser type can accomplish that precision is high, low cost.The micro electronmechanical sonac of condenser type is in the operating frequency range that is designed, and the impedance of its impedance ratio piezoceramic transducer is much lower.So the micro electronmechanical sonac of condenser type does not need the bandwidth of matching layer and broad in medical imaging applications.The micro electronmechanical sonac of condenser type is to be processed by semi-conducting material, so it is more high temperature resistant than piezoelectric ceramics sensor.

The basic structure of the micro electronmechanical sonac of condenser type is a fixedly parallel plate capacitor of bottom electrode and movable top electrode.Movable top electrode is attached to and is used for transmitting ultrasonic wave on the deformable film and receives (RX) ultrasonic wave to the medium that closes on from the medium that closes on.Dc offset voltage can be added in and be used for being provided with film to an optimization position between sensor two electrodes to obtain best sensitivity and bandwidth.During emission (TX), an alternating voltage is added on the sensor.Corresponding electrostatic force moves film to transmit ultrasonic energy to the medium that closes on.During reception,, the ultrasonic wave in the medium changes the electric capacity of sensor thereby causing the colorimetric sensor films vibrations.Capacitance variations can detect with corresponding receiving circuit.

Two kinds of micro electronmechanical sonacs of representational condenser type be respectively the spring bank of micro electronmechanical sonac of deformable films condenser type (flexible membrane CMUT) and invention recently go into the micro electronmechanical sonac of formula condenser type (embedded-spring CMUT, ESCMUT).Fig. 1 is the schematic cross-section of a traditional micro electronmechanical sonac of deformable films condenser type and the enlarged drawing of a sensor primitive 100.Sensor 100 have 110, one of deformable films that 120, one at the fixing lining that comprises a bottom electrode 160 [base] end links to each other withsubstrate 120 throughfilm support 130 movablytop electrode 150 attached on thefilm 110 or in.Film 110 itself also can be used as topelectrode.Film support 130 forms a sensor space 170 (the sensor space can be closed) betweendeformable films 110 and bottom electrode 160.Adielectric insulation layer 140 can optionally be placed between two electrodes.

Spring bank of Fig. 2 is gone into the schematic cross-section of the micro electronmechanical sonac of formula condenser type and the enlarged drawing of a sensor primitive 200.This spring bank go into two pct international patent applications of the micro electronmechanical sonac of formula condenser type (No. PCT/IB2006/051568 and No. PCT/IB2006/05159, the application time is on May 18th, 2006; The title of two patents all is MICRO-ELECTRO-MECHANICAL TRANSDUCERS) there is detailed description the lining.This sensor 200 comprises that 231, one spring layers 220 of 230, one the spring fixtures in a lining [base] end are supported on by spring fixture 231 at the lining [base] end 230.A commercial veneer 210 links to each other with spring layer 220 through a spring thin plate attachment 240.A top electrode 250 is attached on the commercial veneer 210.Commercial veneer 210 itself also can be the part of top electrode.Between top electrode and bottom electrode 260, be sensing space 270.Sensor can be made up of one or more primitives 200.Sensor 200 can have one or more thin plates that supported by spring layer.A dielectric insulation layer 280 can optionally be placed between two electrodes.

Above-mentioned two kinds of micro electronmechanical sonacs of condenser type or PZT piezoceramic transducer in plurality of applications, need add an acoustic lens in its surface in order to the control wave beam.Under most of situation, elastomeric material (for example RTV) is used as the acoustic lens of sensor.This material and water or tissue have very close acoustic impedance, but sound wave propagation therein has very big decay, thereby have reduced the performance of sensor.Another very common way is to make crooked shape to the emitting surface of sensor to focus on.Since the PZT material brittle with and the geometry of sensor performance and sensor relevant, in these application of sensor, be difficult to accomplish needed curved shape.

Fig. 3 makes the micro electronmechanical sonac of condenser type for bending method commonly used; Used amodel 310 of having simplified to represent micro electronmechanical sonac of condenser type (Fig. 1 for example among this figure; The micro electronmechanical sonac of condenser type among Fig. 2), its structure has only comprised thedevice layer 311 andsubstrate 312 of the micro electronmechanical sonac of condensertype.Device layer 311 has comprised other member of micro electronmechanical sonac all except substrate (for example, upper/lower electrode, sensing space etc.).In order to make illustrative simplicity clear, in following sketch map, we use this model of having simplified 310 to represent the micro electronmechanical sonac of various condenser types.Fig. 3 is one of preparation method of the micro electronmechanical sonac of crooked condenser type (sensor 310 comprisessensor 311 andsubstrate 312 thereof).At first make suitable suppleness to the microelectronmechanical sonac 310 of condenser type, and onsensor substrate 320, form the flexure plane 322 (3a) of needs simultaneously.Thensensor 310 is attached on this substrate that design demand flexibility is arranged 320 (like 3b).This method need be to substrate 320 retrofits, and each substrate all is to process in batches, and is higher and time-consuming to requirement on machining accuracy, thereby cost is higher.

Summary of the invention

The objective of the invention is to, to the problems referred to above, it is easy to propose a kind of making, the preparation method of the micro electronmechanical sonac of condenser type of the crooked focusing function of lower-cost band.

For realizing above-mentioned purpose, the technical scheme that the present invention adopts is:

Scheme one:

(1) device layer and the substrate fabrication that will form the condenser type micro-electro-mechanical sensors are one, between sensor base and substrate, place pad;

(2) bending is carried out in the sensor reinforcing of above-mentioned placement pad, up to bending to required flexibility;

(3) the above-mentioned flexibility of maintenance sensor.

According to a preferred embodiment of the invention, above-mentioned pad is attached to substrate or substrate on one of them.

According to a preferred embodiment of the invention, above-mentioned pad directly forms with micro electronmechanical technology etching on substrate or substrate.

According to a preferred embodiment of the invention, bury an etching barrier layer in above-mentioned substrate or the substrate, etching stops at this etching barrier layer place during the above-mentioned pad of etching.

According to a preferred embodiment of the invention, above-mentioned substrate or substrate adopt silicon chip to process, and above-mentioned etching barrier layer is the oxide layer that is embedded in the silicon chip.

According to a preferred embodiment of the invention, above-mentioned substrate and substrate adopt silicon chip to process, and above-mentioned etching barrier layer is the oxide layer that is embedded in the silicon chip.

According to a preferred embodiment of the invention, above-mentioned pad is directly processed with semiconductor packaging process on substrate or substrate.

According to a preferred embodiment of the invention, the pad on above-mentioned substrate or the substrate can be processed with the welding material of semiconductor packaging process.

According to a preferred embodiment of the invention, the welding material of above-mentioned semiconductor packaging process is the solder sphere of Flip-Chip Using technology.

According to a preferred embodiment of the invention, above-mentioned pad can be attached in substrate or the substrate through the wafer bonding method, also can be glued on the substrate through intermediate materials glue or epoxy resin.

According to a preferred embodiment of the invention, can be directly afterburning crooked during bend sensor in the above-mentioned steps (2), also can use cavity and extraneous draught head to come bending.

According to a preferred embodiment of the invention, above-mentioned pad is to be processed by conductor or semi-conducting material.

According to a preferred embodiment of the invention, above-mentioned pad is in order to as the electrical connection between sensor and the substrate.

Scheme two:

(1) form cavity in substrate, with the boundary wall of cavity as pad;

(2) another is had certain thickness substrate and be placed on the pad, covered substrate cavity;

(3) on substrate, make the micro electronmechanical sonac of condenser type;

(4) bend sensor is to required flexibility.

Also comprise:

(5) back-up block that adding packing material or making are swelled below sensor supports the step of sensor.

According to a preferred embodiment of the invention, substrate adopts silicon chip or quartz plate to process.

According to a preferred embodiment of the invention, substrate is silicon chip or uses soi wafer, and makes sonac above that.

According to a preferred embodiment of the invention, can be directly afterburning crooked during bend sensor in the above-mentioned steps (4), also can use cavity and extraneous draught head to come bending.

The bending that technical scheme of the present invention adopts micro electronmechanical or semiconductor and packaging technology thereof to control and realize the micro electronmechanical sonac of condenser type.Be different from substrate and form the bending that a flexure plane is realized the micro electronmechanical sonac of condenser type, technical scheme of the present invention is the decline flexibility of dynamo-electric sonac of accurate control capacitance with a pad.Because this pad can realize with micro electronmechanical or semiconductor fabrication process and packaging technology, so can obtain excellent precision and its cost of manufacture is lower.It is simple also to have method simultaneously, and processing ease is applicable to the beneficial effect of large-scale production.

Through accompanying drawing and embodiment, technical scheme of the present invention is done further detailed description below.

Description of drawings

Fig. 1 is the schematic cross-section of a micro electronmechanical sonac of existing deformable films condenser type;

Fig. 1 a is the enlarged drawing at a place among Fig. 1;

Fig. 2 is the schematic cross-section that an existing spring bank is gone into the micro electronmechanical sonac of formula condenser type;

Fig. 2 a is the enlarged drawing at b place among Fig. 2;

Fig. 3 makes the micro electronmechanical sonac of condenser type with general bending method;

The preparation method of the micro electronmechanical sonac of Fig. 4 embodiment of the invention one described condenser type;

The preparation method of the micro electronmechanical sonac of Fig. 5 embodiment of the invention two described condenser types;

The preparation method of the micro electronmechanical sonac of Fig. 6 embodiment of the invention three described condenser types;

The preparation method of the micro electronmechanical sonac of Fig. 7 embodiment of the invention four described condenser types.

The specific embodiment

Below in conjunction with accompanying drawing the preferred embodiments of the present invention are described.

Embodiment 1:

This example is for controlling and realize one of example of the micro electronmechanical sonac bending of condenser type with micro electronmechanical or semiconductor fabrication process and packaging technology thereof.Specifically be to implement by the method with pad shown in Figure 4.

Making needs the crooked micro electronmechanical ultrasonic sensing device ofcondenser type layer 411 abovesubstrate 412; Below substrate,process pad 413 with micro electronmechanical etching technics; In order to obtain higher precision and uniformity; Etching barrier layer can be set in substrate in advance, so just can highly accurate pad.

The sonac that haspad 410 of above-mentioned making is attached on thesensor substrate 421, and 421 haveplane 420, for example utilize epoxy resin or other bonding methods thatplane 420 is glued topad 413.

Sonac is bent to required flexibility.Directly power is added on the sonac when crooked,crooked substrate 412 is just contacted with 420 faces.Generally speaking, required sonac flexibility is to decide according to the focal position that sonac designs.

4a is the first step of the making of bend sensor among Fig. 4, and apad 413 is produced on the microelectronmechanical sonac 410 of condenser type, andsensor 410 comprises thedevice layer 411 andsubstrate 412 of the micro electronmechanical sonac of condenser type.Can use a generalflat sensor substrate 420 in this case.There is multiple micro electronmechanical etching manufacture craft can directly onsensor base 412, form pad 413.In order to obtain better precision and uniformity; An etching barrier layer can be embedded in thesensor base 412 in advance (for example can use the substrate of a soi wafer as sensor; Wherein insulating oxide is as the etching barrier layer of making in the pad 413), thus etching barrier layer can stop substrate be etched technology excessive or unevenly etching obtain accurate pad height.If necessary, thispad 413 also can be produced on the sensor substrate 420.4b is second step of the making of bend sensor among Fig. 4, will have thesensor 410 ofpad 413 to be attached on the sensor substrate 420.The method of adhering to can have kind very much; Such as using various wafer bonding methods (e.g. eutectic bonding, fusion bonding, eutectic bonding; And thermal compression bonding, flip-chip bonding etc.).Also can use intermediate materials (for example glue, epoxy resin etc.) gummed.4c or 4d are the 3rd steps of the making of bend sensor among Fig. 4, and bend sensor is to the flexibility that needs.Crooked can obtaining with the draught head of space under thesensor 414 with the sensor outside.Bending also can directly be exerted pressure onsensor 411 and obtained.Crooked sensor can touch the surface (like the 4c step) ofsubstrate 420, also can not contact its surface (like the 4d step).4e is the 4th step of the making of bend sensor among Fig. 4, andpacking material 415 can be insertedspace 414 under thesensor.Packing material 415 can be reinforced the bending ofsensor.Packing material 415 can be the material (for example loud consumable material etc.) of matter of having specific characteristics.If the flexibility of sensor can be kept with additive method, this step can be an option.

If pad is to be made by conductor or semi-conducting material, also can use its electrical connection as sensor and substrate.

Embodiment 2:

As shown in Figure 5, be a basic step of coming the flow process of crooked micro electronmechanical sonac with pad.Between micro electronmechanical sonac (comprising its substrate) and sensor substrate, place pad.This pad can be made or attached on the micro electronmechanical sonac, also can make or attached on the sensor substrate.To bend to the flexibility of hope across the sensor on the pad.The flexibility that keeps sensor with appropriate method.

Embodiment 3:

This example for control with micro electronmechanical or semiconductor fabrication process and packaging technology thereof and realize the micro electronmechanical sonac bending of condenser type example two.Specifically be to realize by the method with flip-chip solder ball and welded disc shown in Figure 6.

(1) sonac 611 of the required bending of making abovesubstrate 612; Below substrate, make flip-chip solder ball 613; It is highly accurately controlled;Substrate 620 is processed for the metal material withplane 621, with the substrate of solder ball relevant position on make the weldeddisc 622 and theelectric connection line 623 of solder ball.

(2)sensor 610 is connected withsubstrate 620, promptly flip-chip solder ball and welded disc is packaged together through semiconductor packaging process.

(3) sonac is bent to required flexibility; Can directly obtain when crooked through being pressurized on the sonac; Also can obtain through air pressure betweensubstrate 612 and thesubstrate 620 and extraneous draught head; Can contact withsubstrate plane 621 at substrate bending displacement maximum, also can not contact.Say that from design it is best just to touch sensor substrate surface with sensor displacement maximum.

(4) in substrate and space that substrate does not contact, use flip-chip underfill 625 to fill this step and be option.

6a is the first step of the making of bend sensor, and sensor 610 comprises the device layer 611 and substrate 612 of the micro electronmechanical sonac of condenser type.On sensor 610, add Upper gasket 613.Pad 613 can use the welding material of a lot of semiconductor packaging process (e.g. flip-chip bonding, eutectic bonding etc.) to make.For example pad 613 can be flip-chip (flip-chip) solder ball (solder ball).Sensor substrate 620 can be to process (for example various rigid or flexible PCB etc.) by substrate material layer 621 and the metal level on it.Metal level can be made different patterns, for example can be used for solder ball (solder ball) 613 welded disc 622 and/or electricity interconnect line 623.If desired, welded disc 622 can add UBM (under bump metallization).In addition, wherein the position of welded disc 622 and solder ball 613 can exchange, and for example solder ball (solder ball) 613 can be made on the sensor substrate 620, and welded disc 622 can be made in the substrate 612.6b is second step of the making of bend sensor, and sensor 610 is installed (or encapsulation) on sensor substrate 620.Semiconductor packaging process (e.g. flip-chip bonding, eutectic bonding etc.) can directly use in this step.Flip-chip solder ball 613 not only can also can be used as the electrical connection between sensor 610 and the sensor substrate 620 simultaneously with the flexibility that decides after the sensor bending.6c is the 3rd step of the making of bend sensor, and bend sensor is to the flexibility that needs.In general, it is best just to touch sensor substrate 620 surfaces with sensor displacement maximum.6d is the 4th step of the making of bend sensor, if necessary, can be filled into material 625 and help the sensor of stationary curved better below the sensor 610.This material can be the underfill (underfill material) that uses in the flip-chip (flip-chip).

Embodiment 4:

This example for control with micro electronmechanical or semiconductor fabrication process and realize the bending of the micro electronmechanical sonac of condenser type example three.Specifically be to implement by the substrate that usefulness shown in Figure 7 has a cavity.

In thesubstrate 721 with silicon wafer to manufacture, dig anempty hole 714, the height of theboundary wall 713 around the cavity is accurately controlled with micro electronmechanical technology.

The silicon chip that to use suitable thickness is assubstrate 712, and the micro electronmechanical technology ofsubstrate 712 usefulness is placed on theempty hole 714.

Onsubstrate 712, make sonac.According to the requirement of concrete making flow process, the making of sonac can be before or aftersubstrate 712 is placed on theempty hole 714, to carry out.

The bending ultrasonic sensor is to needed flexibility, through sonac directly afterburning mode or the draught head inside and outside the cavity are carried out bending.7a is the first step of the making of bend sensor, on base (sheet) end 721 of sensor production, digs earlier empty hole (recession/cavity) 714, and the boundary wall 713 in empty hole 714 just can be used as pad.This substrate can be a silicon chip, sheet glass or quartz plate etc.7b is second step of the making of bend sensor, forms cavity thereby need the substrate 712 of thickness to be placed on the empty hole 714 another then.This substrate 712 can be with general silicon chip then wear down also can be to use soi wafer to the thickness that needs, use the substrate of its device layer then as sensor.According to the material that uses and the requirement of manufacture craft, substrate 712 can be placed on different micro electronmechanical technology on the empty hole 714, for example fusion bonding; Anodic bonding; Eutectic bonding, or thermal compression bonding, or the like.7c is the 3rd step of the making of bend sensor, on substrate 712, makes the micro electronmechanical sonac 711 of condenser type.According to the actual conditions of manufacture craft or manufacturing materials, the 3rd step (7c) and the first step (7a) and the making order in second step (7b) can exchange.And can on substrate 712, make sensor 711 earlier, place it in then on the sky hole 714 of substrate.7d or 7e are the 4th steps of the making of bend sensor, and bend sensor is to needed flexibility.Bending is plus-pressure directly, also can utilize cavity and extraneous draught head to realize.Substrate 712 bottoms of bend sensor can touch the bottom 722 (like the 7e step) of cavity, also can not contact (like the 7d step).If the substrate of bend sensor 712 bottoms touch cavity the bottom, in order to control the scope of contact, also can make the back-up block 723 (like the 7f step) of the protuberance of a small size in advance in the bottom portion of being in contact with it.If desired, can be filled into material and help the sensor of stationary curved better below the sensor.When crooked sensor can be placed directly in sensor package on the used substrate.

What should explain at last is: the above is merely the preferred embodiments of the present invention; Be not limited to the present invention; Although the present invention has been carried out detailed explanation with reference to previous embodiment; For a person skilled in the art, it still can be made amendment to the technical scheme that aforementioned each embodiment put down in writing, and perhaps part technical characterictic wherein is equal to replacement.All within spirit of the present invention and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (18)

1. be with the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on; It is characterized by; Preparation method may further comprise the steps: device layer and the substrate of condenser type micro-electro-mechanical sensors will be formed as one in (1), between sensor base and substrate, place pad;

(2) bending is carried out in the sensor reinforcing of above-mentioned placement pad, up to bending to required flexibility;

(3) the above-mentioned flexibility of maintenance sensor.

2. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 1 is characterized by, and above-mentioned pad is attached to substrate or substrate on one of them.

3. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 2 is characterized by, and above-mentioned pad directly forms with micro electronmechanical technology etching on substrate or substrate.

4. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 3 is characterized by, and buries an etching barrier layer in above-mentioned substrate or the substrate, and etching stops at this etching barrier layer place during the above-mentioned pad of etching.

5. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 4 is characterized by, and above-mentioned substrate or substrate adopt silicon chip to process, and above-mentioned etching barrier layer is the oxide layer that is embedded in the silicon chip.

6. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 4 is characterized by, and above-mentioned substrate and substrate adopt silicon chip to process, and above-mentioned etching barrier layer is the oxide layer that is embedded in the silicon chip.

7. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 2 is characterized by, and above-mentioned pad is directly processed with semiconductor packaging process on substrate or substrate.

8. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 2 is characterized by, and the pad on above-mentioned substrate or the substrate can be processed with the welding material of semiconductor packaging process.

9. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 8 is characterized by, and one of welding material of above-mentioned semiconductor packaging process is the solder sphere of Flip-Chip Using technology.

10. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 1; It is characterized by; Above-mentioned pad can be attached in substrate or the substrate through the wafer bonding method, also can be glued on the substrate through intermediate materials glue or epoxy resin.

11. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 1 is characterized by, can be directly afterburning crooked during bend sensor in the above-mentioned steps (2), and also can use cavity and extraneous draught head to come bending.

12. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 1 is characterized by, above-mentioned pad is to be processed by conductor or semi-conducting material.

13. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 12 is characterized by, above-mentioned pad is in order to as the electrical connection between sensor and the substrate.

14. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band is characterized by preparation method and comprises:

(1) form cavity in substrate, with the boundary wall of cavity as pad;

(2) another is had certain thickness substrate and be placed on the pad, covered substrate cavity;

(3) on substrate, make the micro electronmechanical sonac of condenser type;

(4) bend sensor is to required flexibility.

15. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 14 is characterized by also and comprises:

(5) back-up block that adding packing material or making are swelled below sensor supports the step of sensor.

16. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 14 is characterized by, above-mentioned substrate adopts silicon chip or quartz plate to process.

17. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 14 is characterized by, above-mentioned substrate is silicon chip or uses soi wafer, and makes sonac above that.

18. the preparation method of the crooked micro electronmechanical sonac of condenser type that focuses on of band according to claim 14 is characterized by, can be directly afterburning crooked during bend sensor in the above-mentioned steps (4), and also can use cavity and extraneous draught head to come bending.

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