JPS61501302A - How to attach the SAW element and its structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] SAW element mounting method and its structure [Technical field] The present invention relates to the structure and mounting method of surface acoustic wave (SAW) devices.

[Background technology]

For example, the SAW element is connected to an electronic circuit and used as a bandpass filter. Noriyoshi A typical known SAW device has a rectangular crystal substrate, and a metal electrode is placed on the surface of this substrate. poles are formed. These electrodes should be connected to the circuit with proper leads. Can be done. The substrate is mounted on a metal support and connected by an organic adhesive. Yes Machine adhesive is usually attached to the board. ! Sound formed around the edges and from the end face of the crystal A metal-mounted pancase that acts as an acoustic absorber to reduce acoustic reflections. is impractical for use on thick film circuit boards containing surface-mounted components. stomach. In order to use such metal packages, the thick film is temporarily removed by laser drilling. It is also possible to provide holes for mounting, but this is expensive. Apart from this, there are SAW elements can also be attached directly to circuit boards using mechanical adhesives. but , organic adhesives emit gases such as chlorides and water vapor, and the SAW devices use For this reason, conventional SAW devices are It was puff caged and separated from the circuit.

The present invention can be completed by attaching directly onto the hybrid circuit without using adhesive. The present invention relates to a method for mounting a SAW device that can realize a device similar to the above.

[Disclosure of the invention] According to the first aspect of the invention, one or more regions metalized on the surface of the first substrate A conductive lead wire is attached to this metalized area, and the first base is connected to the metallized area. The surface of the plate is placed near the selected surface of the second board and the lead wires are connected to this second board. contact the conductive area on the second substrate, and connect the lead wire to the conductive area on this second substrate. Attach the above lead wires and the above first conductive area on the above second board. Mounting the SAW element holding the substrate provides a solution.

This method involves applying a plurality of the above-mentioned metal layers on a piece of material that is passed through to form a SAW device. forming an area where the material has been removed, and this is followed by applying the material to the attachment of the lead wire. The method may include the step of cutting out individual elements beforehand.

A particularly advantageous shape for SAW substrates is generally known to be diamond-shaped. this When a shape is used, there is no need for an acoustic absorber at the end of the element.

Yumata allows lead wires to be attached to metalized areas by thermocompression bonding. , the lead wire can be attached to the conductive region of the second substrate by thermocompression bonding. No. A hybrid circuit is used as the second substrate.

The metallized area of the SAW substrate consists of an aluminum (Af) layer and a gold (Au) layer. layer, aluminum layer and gold layer to prevent interdiffusion between aluminum and gold. It is desirable to form a titanium (Ti) layer between the two.

The lead wires and conductive regions on the second substrate are formed of gold (Au).

The SAW substrate is made of crystal.

Devices formed using this method are particularly suitable for use in thick film and thin film hybrid circuits. Ru.

According to another aspect of the invention, a semiconductor region is formed and a SAW is formed on the conductive region. The SAW device is attached to the substrate and the metallization on the substrate. a conductive lead wire attached to the region; and a conductive lead wire attached to the region. provides a hybrid circuit which is a structure connected to the conductive region.

According to yet another aspect of the invention, a substrate and a metallized area on said substrate. and a SAW element with conductive leads attached to the metallized area. provide a child. It is generally desirable that the substrate be diamond-shaped.

The invention will now be described by way of example, with reference to the accompanying drawings.

[Brief explanation of the drawing]

FIG. 1 shows the first step of the method of the invention.

FIG. 2 is a plan view of a SAW device formed according to the present invention.

FIG. 3 shows the upper side of the SAW element mounted on the substrate.

FIG. 4 is a plan view of a typical conductive pattern on a substrate.

FIG. 5 shows a partially cut out conductive pattern and SA before mounting on the substrate. It is a perspective view of a W element.

[Best mode for carrying out the invention]

In the method of the invention, in a first step, the surface of a quartz crystal plate, generally designated 10, is Forming multiple metalized areas. In Figure 1, there is essentially one SAW element. Only child-related areas are shown; In order to be able to simultaneously form the same area, the plate 10 is made of a material much larger than the area shown. The metallized areas are shown at 11 in FIG. An L-shaped layer 12 made of aluminum (A1) and partially on one leg of the L-shaped A matrix of gold and aluminum including a rectangular layer 14 formed of gold (Au) overlapping the Titanium (Ti) is added between the gold and aluminum to prevent migration. It is desirable to form a layer.

After forming the metallized areas, each crystal slab is cut into individual elements. Each individual element is indicated by line 16 in FIG. 1, and it can be seen that this element is diamond-shaped. No. Attach metal tape to the gold bonding area on the surface of each element as shown in Figure 2. Ru. The metal tape is indicated by reference number 18, and each gold bond is attached by thermocompression bonding as described below. attached to the area. Typical dimensions of each element are shown in FIG.

Referring to FIG. 5, each SAW element is then configured as follows. and attached to the hybrid circuit board. The surface where the lead wire 18 is attached is facing downward. Flip the element so that the The conductive patterns shown in Figures 4 and 5 The elements are placed on a hybrid wiring board with The conductivity of the lead wire was 30 on the 1st day. The element is placed so that it is held over the area. Referring to FIG. 3, lead wire 18 It can be seen that they face and contact the conductor 30 and are thereby held.

Lead wire 18 is attached to conductor 30 by thermocompression to create a complete configuration.

The present technology is more efficient than the conventional technology in terms of the amount of noise. Reduce end reflections without the need to use attenuating materials.

The technique of using tape adhesive to attach devices to a circuit board allows for the installation of low profile devices. can be realized and used with the conductor configuration shown in Figure 4 to create a 5AW) transducer. This helps reduce TM breakthroughs during the period. crystal from hybrid substrate The tape can be formed in such a way that stress is not transmitted to the substrate.

In the conductor configuration shown in FIGS. 4 and 5, the area designated by reference numeral 34 is grounded. shielding, which helps reduce the electromagnetic breakthroughs mentioned above.・ The main feature of the method is that it does not use organic adhesives in any form. death Therefore, the problem of outgassing from such compounds does not occur, and the SAW device can be It is possible to attach directly to the hybrid circuit board.

This mounting method also reduces the stress applied to the crystal substrate during operation.

In prior art configurations, the soundboard compound securely holds the SAW element. This is gold This problem, which does not allow for thermal expansion of the substrate associated with bulk puff cages, is addressed by the present invention. This is not so much of a problem in the configuration shown in Figure 3. It can be seen that the image is held in an area corresponding to the totalization area 11. this is, Provides a relatively stress-free installation that reduces aging of the SAW element and provides long-term reliability. Improve reliability as much as possible.

(example) The applicant has developed a SAW filter using natural crystal cut out on the ST plane with a thickness of 1. Manufactured. Print interdigitated transducers and use optical photoetching 0 example etched into 150nm thick aluminum metallization. BA, Flurry, JM (FI?ARY, J Gate) and Seth 1P (SE SSE, P): Lift-off technology for fine interconnect metal patterns -off Techniques for Fine Line? Ital Patterning) J, Semiconductor International (Sea+ 1-conductor Tnational), December 1981, aluminum using a lift-off process as described on pages 72-88. Determine the titanium and gold adhesive pad on the tip of the finger. crystal, diamond cut The device is completely cut out from the substrate using a microprocessor and separated into individual devices. edge as mentioned above Cut the crystal into diamond-shaped chips to minimize the effects of reflections. at the top of the chip Acoustic waves traveling in the direction are greatly attenuated due to multiple reflections between the converging edges. .

To attach the SAW chip, connect the gold tape leads to the transducer. Attach it to the mounting pad and place it on the Vibelift base with the tip side facing down as described above. Attach directly to the board.

Gold plate with purity of 99.99%, actual thickness of 0.0751mm, width of 0.375mm+ A loop was used as a lead wire. Just before use, cut the tape to 311III+ length. The sample was taken out and annealed in air at 800°C for 15 minutes. Beam re to SAW chip A hard steel layer sharpener replaces the usual vacuum-operated suction collet to attach the wire. (DagePrecima Gui with sharp adhesive) ・Used bonder. Place each lead on the adhesive pad of each transducer. One end was placed and thermocompression bonded using the tip of a connector having a diameter of 0.125 mm. this The treatment was carried out at a temperature of 250° C. with a force of 0.6 N in a dry nitrogen atmosphere. Ta.

The lead wire distorted the plane of the crystal surface during bonding. Grind the chia cleanly with one side facing down. By placing it on a polished glass surface and applying a small force to the back side of the crystal, I got my sex back.

At this time, place the chip with the end of the gold lead wire on top of the thick gold adhesive island, and the acoustic surface facing down. I decided to put R on the hybrid. The hybrid is bonded with the heated chuck of the bonding machine. and re-use the adhesive used to attach the leads to the SAW chip. The lead wires were then glued to the thick film. When creating these board bonds, the lead wires tended to become cantilevered. To prevent movement, do not touch the chip while gluing. I applied force to the back of the tap.

Transducers with titanium and gold adhesive pads were mechanically tested and Give the lead wire a tensile strength exceeding 0.5N, and if these elements fail, they will be replaced. This was due to damage to the cable. In contrast, the gold lead wire is placed on the SAW chip. When bonded directly to the aluminum adhesive band, the tensile strength of the lead wire is It is several grams, and the failure occurs due to the aluminum metal being lifted from the crystal substrate. Ta. SAW devices assembled with titanium and gold adhesive bands were I gave it a shock at 180 Hz (intensity of 20 g) and vibrated it for 1 minute, but it did not break down. won.

Attaching a SAW device according to the method of the present invention also improves the performance of the SAW device.

First, electromagnetic breakthroughs can be achieved by using low-profile adhesive leads. Second, placing the ground plane on the thick film circuit very close to the transducer of SAW elements mounted in this way, resulting in excellent screening. Stopband rejection was improved by 10 dB overall. lip introduced into the amplitude response The signal was approximately ±0.05 dB.

A, NNEX To T’E! w fNTER)lAτl0NAf, SE,' h:’IcHREPORτ01゜

Claims (16)

[Claims] 1. One or more metallized regions are provided on the surface of the first substrate, and the metallized Attach a conductive lead wire to the area where the Place the above leads into conductive areas on this second substrate by placing them near the selected surface. and attach the above lead wire to the conductive area on this second substrate and connect the above lead wire to the conductive area on this second board. a SAW element holding the first substrate over a conductive region on the second substrate; How to install the child. 2. Multiple metallized areas on a piece of material suitable for forming a SAW device and after this the above material is individually attached before attaching the above lead wires. and cutting out the SAW element according to claim 1. How to attach. 3. The SAW substrate according to claim 1 or 2, wherein the SAW substrate is substantially rhombic. How to install AW element. 4. Claims in which the lead wire is attached to the metallized area by thermocompression bonding. A method for attaching a SAW element according to any one of Items 1 to 3. 5. Claims wherein the lead wire is attached to the conductive area of the second substrate by thermocompression bonding. A method for attaching a SAW element according to item 4. 6. Any of claims 1 to 5, wherein the second board is a hybrid circuit. A method for attaching a SAW element as described in any of the above. 7. The metallized area of the SAW substrate includes an aluminum layer and a gold layer. A method for attaching a SAW element according to any one of items 1 to 6. 8. between the aluminum and gold layers to prevent aluminum and gold interdiffusion. A method of attaching a SAW element according to claim 7, in which a titanium layer is formed on Law. 9. The leads and conductive areas on the second substrate are formed of gold (Au). A method for attaching a SAW element according to any one of items 1 to 8. 10. Any one of claims 1 to 9, wherein the SAW substrate is formed of quartz crystal. A method for attaching a SAW element as described in any of the above. 11. A conductive region is formed and a SAW element is mounted on the conductive region. The SAW device consists of a substrate, a metallized area on this substrate, and a metalized area attached to this area. a conductive lead connected to the conductive area; A hybrid circuit with a unique structure. 12. a substrate, a metallized area on the substrate, and a metallized area on the substrate; A SAW element having a conductive lead wire attached to the area. 13. 13. A SAW device according to claim 12, wherein the substrate is substantially rhombic. 14. A method of attaching a SAW element substantially as described above. 15. A hybrid circuit substantially as shown in and described with reference to the accompanying drawings. 16. A SAW device substantially as shown in and described with reference to the accompanying drawings.