SAW the whole production process can be divided into four parts: substrate preparation, graphics preparation, electrode production (before the procedure) and after the procedure
Most SAW devices are single-crystal substrates, but also a certain degree of cutting oriented. So first of all to the single-crystal X-ray orientation, and then determine the direction of a good space on the crystal slice cut next movie, and marked on the chip surface acoustic wave's propagation direction, cut the chip also needs to be removed polishing surface. These are very complex process, Fortunately, surface acoustic wave devices in general the use of building materials commonly used only a few: 128LN, 41LN, 64LN, YZLN, 112LT, 36LT, 42LT, 36QZ and so on, work with the substrate is generally large wafer, wafer production in the first repeated with a series of two-dimensional graphics。Then it is separated into many components, graphics in general do in the polished surface, the back generally fail to address them, in body-wave suppression requirements are particularly high requirements when playing back hair, or even to open a trench, and then coated with sound-absorbing material (IF general required).
SAW is designed to calculate the IDT should have what kind of graphics performance needed to get. With the graphics data, the graphics can be produced in two ways: one is the use of graphics generator, according to the data entry process, a direct consequence of graphics, more precise, but the high cost of equipment; the other is to enlarge the graphics after a number of times with engraved map carved in red membrane machines, photographic equipment and then use the plate reduced the formation of particles in the ultra-dry black-and-white graphics board. If too narrow the multiples can be refined later THPC reduction. Dry plate that ultrafine particles can be directly used as a lithography mask. Carved mask.When the high-volume production on many occasions when the mask to use, particles can also be super dry plate as Copy motherboard into chromium plate, the use of chromium plate lithography.
Electrode production process, including coating and lithography. Clean in the whole process is a matter of paramount importance. Any time there is one point on the substrate contamination and dust will cause the graphics electrode defect, resulting in electrodes graphics or even be broken, or there is not strong electrode adhesion, so that devices can not be used, so a good cleaning is the key, in the process must always kept clean and no pollution, dust and so on. Clean the chip with a metal-plated film (such as gold, silver, aluminum, etc.), method of coating evaporation or sputtering can be used. Lithography method is used gum off the plane in the substrate left on the thin layer of uniform layer.Lithography machine and then through the plastic template on the photographic exposure, the corrosion had removed the light exposed part of the glue left behind as a protective layer of metal film to the film from the metal film corrosion protection off. Corrosion can be used wet etching solution, can also be used dry etching plasma. Finally, the remaining plastic and then removed the sensor, so that has been needed for graphics electrode can also be carried out in turn (spin-off process), the first lithography, after coating, removing the final remnants of the photoresist, this time engraved on the plastic part of the metal film was taken at the same time, the same electrode can be required for graphics.
After the whole procedure, including:
Dicing: large wafer into an independent design;
Film: Block the chip with the management agent used to glue together film;
Spot: The ultrasonic welding press with the graphics on the Si-Al wire electrode and the convergence device of the pin tube socket connect;
Tu sound-absorbing material: the general TV-IF filter and transmission, and used to absorb the reverse-wave suppression face waves and body wave reflection.
Packaging: General parallel closures welding (metal patch SMD-3), energy storage closure welding (metal category F11 F12 TO39 D3512 Etc.), and epoxy potting (SIP5D SIP5K of plastic and ceramic types of SMD-2)
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