A method for efficiently and non-destructively preparing a multi-element wafer assembly

Abstract

The present application relates to a kind of high-efficiency lossless preparation multi-element wafer assembly method, the method utilizes the high bonding strength of water boiling glue epoxy adhesive, excellent water boiling glue, glue layer soft characteristics, so that piezoelectric ceramic small particle does not fall in wafer assembly preparation process, substrate removal is simple and easy, and does not damage the electrode surface of piezoelectric ceramic small column, including the following steps: surface treatment;Gluing;Cutting;Washing, normal temperature air dry;Low-temperature prebaking, fill high molecular decoupling material, remove the decoupling material on the electrode surface of piezoelectric ceramic small particle clean;Solidification;Polish and remove substrate;Remove excess particles to form approximately circular wafer assembly;Positive and negative electrode line lead out.The present application prepares multi-element wafer assembly method, utilizes the high bonding strength of water boiling glue epoxy adhesive, good impact resistance characteristics, overcomes the problem that its bonding strength is reduced due to factors such as water vapor and temperature in preparation process, and does not damage the electrode surface of piezoelectric ceramic small column.

Description

TECHNICAL FIELD

[0001] The present application relates to the preparation technology of multi-element wafer assembly in underwater acoustic transducer, in particular to a method for efficiently and non-destructively preparing multi-element wafer assembly. BACKGROUND

[0002] The Doppler log in underwater acoustic transducer is mainly used for measuring the speed and distance of a ship. Compared with the traditional Doppler log, the phased array Doppler log uses only one multi-element circular planar array for phased transmission and reception, which can complete the formation of multiple beams, omit the cumbersome steps of sound velocity compensation, greatly reduce the weight and total size of the underwater base array, and is widely used in low-frequency, large-range speed measurement and other fields. The multi-element circular planar array in the phased array is a multi-element wafer assembly composed of hundreds to thousands of piezoelectric ceramic small columns and decoupling polymer materials. Each ceramic small column in the wafer assembly is arranged in order according to a certain interval, and the interval is filled with high-insulation decoupling materials such as polyurethane, flexible epoxy, and silicone rubber. The number and size of the piezoelectric ceramic small columns are related to the acoustic performance parameters of the planar array.

[0003] The manufacturing method of the multi-element wafer assembly is to bond and fix the complete piezoelectric ceramic sheet (the circular piezoelectric ceramic sheet is commonly used) with the substrate, and then cut in the X direction and the Y direction respectively, cut the complete piezoelectric ceramic sheet into an orderly arranged independent piezoelectric ceramic small column, fill the decoupling material such as polyurethane in the gap between the piezoelectric ceramic small columns, and finally remove the substrate by some way to complete the manufacturing of the multi-element wafer assembly. There are two key points: (1) the bonding and fixing of the piezoelectric ceramic sheet and the substrate; (2) the removal of the substrate. The reason is that the piezoelectric ceramic sheet will bear a large shear force and internal stress during cutting and filling, and if the bonding strength between the piezoelectric ceramic sheet and the substrate is not enough, the cut piezoelectric ceramic small column will be tilted during the preparation process, so the bonding strength between the piezoelectric ceramic sheet and the substrate needs to be strong. For this process of removing the substrate, due to the strong bonding strength between the piezoelectric ceramic sheet and the substrate, the silver electrode surface of the piezoelectric ceramic is easily damaged when removing the substrate. Compared with the 1-3 type piezoelectric composite material which is a whole vibration module and only needs to draw a positive and negative electrode, each ceramic small column in the multi-element wafer assembly is an independent vibration element and needs to draw a positive and negative electrode separately, so it is particularly important to avoid damage to the silver electrode surface of each ceramic column during the preparation process.

[0004] Currently, there are several commonly used methods for the preparation of multi-element wafer assembly in the industry. Method one: the piezoelectric ceramic and the substrate are bonded and fixed by using acrylic fast-drying adhesive and epoxy adhesive with high bonding strength, and then cut in X and Y directions at one time, then fill polyurethane decoupling material and solidify, and finally remove the substrate; the piezoelectric ceramic is bonded and fixed by using acrylic fast-drying adhesive, and since the adhesive layer is very thin and the solidification stress is large, the silver electrode surface is easily damaged when the substrate is removed; when the piezoelectric ceramic is bonded and fixed by using epoxy adhesive, since the bonding strength is high, the silver electrode surface is easily pulled off when the substrate is removed, and additional polishing and electrode coating processes are required, and it is difficult and complex to coat the electrodes on hundreds of thousands of piezoelectric ceramic small particles arranged in the same plane and the decoupling material between the small particles has no metal electrode. In addition, there are two methods for repairing the damaged electrode surface, namely, silver infiltration and silver magnetron sputtering, and the temperature of the former can reach more than 800℃, and the high molecular decoupling material filled in the gap between the ceramic small columns cannot withstand it, and the quality of the silver electrode surface of the latter cannot meet the welding requirements, affecting the electrode lead reliability. Method two: the piezoelectric ceramic electrode surface is not directly bonded with the substrate, but the piezoelectric ceramic sheet is bonded and fixed with the substrate around the periphery by using epoxy adhesive, so as to avoid the problem of damaging the piezoelectric ceramic electrode surface when the substrate is removed, but this method requires X and Y direction cutting respectively, that is, X or Y direction cutting, cleaning, filling is completed, and then the other direction cutting, cleaning, filling is carried out, which is multiple processes, long cycle and low efficiency. In addition, due to the inconsistent solidification shrinkage of the polyurethane filled twice, the uniformity and stability of the prepared wafer assembly are poor. Method three: implantation method, the ceramic small column is directly embedded into the template made of decoupling material with pre-processed ceramic small column placement position to make multi-element ceramic wafer assembly. The material characteristics and processing precision of the high molecular decoupling material itself result in low position precision and electrode surface flatness of the ceramic small column, and each ceramic small column in the multi-element wafer assembly for phased array Doppler log is an independent vibration element, and the position precision and electrode surface flatness have a direct impact on the acoustic performance of the phased array. SUMMARY

[0005] To solve the above technical problems, a method for efficiently and non-destructively preparing a multi-element wafer assembly according to the present application utilizes the high bonding strength, excellent water boiling glue, and soft glue layer characteristics of the water boiling glue epoxy adhesive, so that the piezoelectric ceramic small particles do not fall during the wafer assembly preparation process, the wafer substrate is easy to remove, and the piezoelectric ceramic small column electrode surface is not damaged, and the method comprises the following steps:

[0006] Step S1: surface treatment; roughening and oil removal treatment are respectively performed on the bonding surface of the substrate and the bonding surface of the piezoelectric ceramic electrode;

[0007] Step S2: gluing; water boiling glue epoxy adhesive is applied to the bonding surface, the clamp is forced, and it is placed at room temperature for more than 24 hours;

[0008] Step S3: cutting; cutting in X, Y direction of the substrate at one time;

[0009] Step S4: cleaning, air drying at room temperature;

[0010] Step S5: low-temperature pre-baking, filling polymer decoupling material, vacuum pumping, wiping off the excess decoupling material on the ceramic upper electrode surface, or shoveling off the excess decoupling material on the ceramic upper electrode surface when it is initially solidified, and warming and solidifying;

[0011] Step S6: mechanically and by water boiling to remove the decoupling material around the piezoelectric ceramic and the substrate;

[0012] Step S7: removing the excess particles to form a nearly circular wafer assembly according to the acoustic performance of the planar array;

[0013] Step S8: leading out the positive and negative electrode wires.

[0014] In an embodiment of the present application, in order to overcome the problem of the ceramic small column toppling caused by the water vapor and temperature affecting the bonding strength during the preparation process, the water boiling adhesive epoxy in step S2 has a tensile bonding strength > 10 MPa, a Tg of about 120℃, and a hardness of about 80 Shore D; before the initial solidification of the filled decoupling material, the process does not put the piezoelectric ceramic in a high-temperature and humid environment.

[0015] In an embodiment of the present application, if the cooling liquid is water when cutting in step S3, water immersion, flushing, brushing or ultrasonic cleaning is adopted in step S4; if the cooling liquid is oil when cutting in step S3, oil immersion or brushing is adopted in step S4.

[0016] In an embodiment of the present application, the decoupling material used in step S5 is polyurethane elastomer, flexible epoxy, epoxy or silicone rubber, and preferably polyurethane elastomer or flexible epoxy.

[0017] In an embodiment of the present application, the temperature of the low-temperature pre-baking in step S5 is 45-70℃; the curing temperature and time of the filled decoupling material are different, and the interval range is 50-100℃ for 3-24h.

[0018] In an embodiment of the present application, in order not to damage the electrode surface of the piezoelectric ceramic small column when removing the substrate in step S6, the water boiling removal of the substrate in the present application is to grind the substrate to an extremely thin layer or grind it off; when the epoxy adhesive is removed by water boiling, the water vapor can infiltrate the epoxy adhesive to accelerate its softening and separation from the piezoelectric electrode bonding surface.

[0019] The above technical scheme of the present application has the following advantages compared with the prior art: the method for preparing the multi-element wafer assembly has the characteristics of high bonding strength and good impact resistance of the water boiled glue epoxy adhesive, overcomes the problem of reduced bonding strength caused by water vapor and temperature in the preparation process, realizes one-time X and Y direction two-knife cutting, cleaning, filling, and the piezoelectric ceramic small column does not fall over; the water boiled glue epoxy adhesive has the characteristics of water boiled glue and soft glue layer, so that the substrate removal is simple and easy, and the electrode surface of the piezoelectric ceramic small column is not damaged. DETAILED DESCRIPTION

[0020] Embodiment one

[0021] The present embodiment provides a method for efficiently and losslessly preparing a multi-element wafer assembly, comprising the following steps:

[0022] Step S1: surface treatment. Select ceramic pieces with a diameter of 80 mm and epoxy wood boards with a size of 120*120*8 mm, polish the bonding surface of the wood board with coarse sandpaper to obtain a fresh surface, clean it with acetone; clean the ceramic bonding surface with detergent powder + white cat, slightly polish it with fine sandpaper, and clean it with acetone;

[0023] Step S2: gluing. Apply water hydrolysis epoxy adhesive to the treated bonding surfaces, place the piezoelectric ceramic bonding electrode surface on the substrate adhesive bonding surface at an angle, apply force with the clamp, control the glue layer thickness to be three to fifty filaments through the tooling, and place it at room temperature for 24 hours;

[0024] Step S3: outsourcing X and Y direction cutting (one-time cutting of two knives), the cutting center distance is 3.25, and the cutting coolant is water;

[0025] Step S4: soak in water for 30 minutes, rinse with water twice, and dry;

[0026] Step S5: pre-dry in a 60°C oven for 2 hours, fill with JA-2S polyurethane, vacuum for 10 minutes, remove the polyurethane on the electrode surface of the piezoelectric ceramic when the polyurethane is initially cured, and solidify at 100°C for 4 hours;

[0027] Step S6: mechanically remove the decoupling material around the piezoelectric ceramic, grind the substrate to a thin layer or directly grind it off;

[0028] Step S7: place in boiling water, remove the residual substrate or water hydrolysis epoxy adhesive with a blade after 15-20 minutes;

[0029] Step S8: remove the excess particles to form a nearly circular wafer assembly;

[0030] Step S9: positive and negative electrode wire lead-out.

[0031] Embodiment two

[0032] The embodiment provides a method for efficiently and losslessly preparing a multi-element wafer assembly, which comprises the following steps:

[0033] Step S1: surface treatment. A ceramic sheet with a diameter of 150 mm and a bakelite plate with a size of 120*120*10 mm are selected, the bonding surface of the bakelite plate is polished to a fresh surface with coarse sandpaper and cleaned with acetone; the ceramic bonding surface is scrubbed with detergent powder and white cat, dried and cleaned with acetone;

[0034] Step S2: gluing. The treated bonding surfaces are respectively smeared with hydrolytic epoxy glue, the piezoelectric ceramic bonding electrode surface is slowly placed on the bonding surface of the substrate with glue, the clamp is forced, the glue layer thickness is controlled to be three to fifty filaments through a tool, and the clamp is placed at room temperature for 24 hours;

[0035] Step S3: outsourcing X and Y direction cutting (cutting twice), the cutting center distance is 6.25 mm, and the cutting coolant is water;

[0036] Step S4: ultrasonic cleaning twice, each time for 10 minutes, the ultrasonic power is 1700 W, and the frequency is 20 KHz;

[0037] Step S5: pre-drying in a 70 DEG C oven for 2 hours, pouring JA-2S polyurethane, vacuum pumping for 10 minutes, shoveling off the polyurethane on the electrode surface of the piezoelectric ceramic when the polyurethane is preliminarily solidified, and solidifying at 90 DEG C for 6 hours;

[0038] Step S6: mechanically removing the decoupling material around the piezoelectric ceramic, and grinding the substrate to a thin layer or directly grinding off;

[0039] Step S7: placing in boiling water, removing the residual substrate or hydrolytic epoxy adhesive with a blade after 15-20 minutes;

[0040] Step S8: removing the excess particles to form a nearly circular wafer assembly;

[0041] Step S9: positive and negative electrode wire leading out.

[0042] Embodiment 3

[0043] The embodiment provides a method for efficiently and losslessly preparing a multi-element wafer assembly, which comprises the following steps:

[0044] Step S1: surface treatment. A ceramic sheet with a diameter of 100 mm and a bakelite plate with a size of 120*120*12 mm are selected, the bonding surface of the bakelite plate is polished to a fresh surface with coarse sandpaper and cleaned with acetone; the ceramic bonding surface is scrubbed with detergent powder and white cat, dried and cleaned with acetone;

[0045] Step S2: gluing. The treated bonding surfaces are respectively coated with hydrolyzed epoxy glue, the piezoelectric ceramic bonding electrode surface is slowly placed on the bonding surface of the substrate coated with glue, the clamp is forced, the glue layer thickness is controlled by the tool to be 30-50 filaments, and the clamp is placed at room temperature for 24 hours;

[0046] Step S3: outsourcing X and Y direction cutting (cutting twice), cutting center distance is 5mm, and cutting cooling liquid is water;

[0047] Step S4: ultrasonic cleaning twice, each time for 10 minutes, ultrasonic power is 1400W, and frequency is 20KHz;

[0048] Step S5: pre-drying for 2 hours in a 45 DEG C oven, flexible epoxy resin, vacuum pumping for 15 minutes, wiping the excess flexible epoxy resin on the upper surface of the piezoelectric ceramic clean, and curing at 80 DEG C for 8 hours;

[0049] Step S6: removing the decoupling material around the piezoelectric ceramic by mechanical removal, and grinding the substrate to a thin layer or directly grinding off;

[0050] Step S7: placing in boiling water, removing the residual substrate or hydrolyzed epoxy adhesive with a blade after 15-20 minutes;

[0051] Step S8: removing the excess particles to form a nearly circular wafer assembly;

[0052] Step S9: positive and negative electrode wire lead-out.

[0053] The piezoelectric ceramic sheet is bonded and fixed by using boiled hydrolyzed epoxy adhesive, X and Y direction cutting and cleaning and pouring are reduced to once, the whole manufacturing process is reduced by three processes, the substrate removal is simple and easy to operate, and the electrode surface is not damaged, the process of re-coating the electrode is omitted, the processing period is greatly reduced, the production efficiency is improved, the production cost is greatly reduced, the quality control cost and the pollution cost are also reduced. The influence of the inconsistent shrinkage of the polyurethane caused by twice pouring due to twice cutting on the uniform stability of the wafer element and the assembly is avoided, and the stability of the multi-element wafer assembly is improved. In addition, the present application can also be applied to the preparation of other two-dimensional and three-dimensional multi-element wafer assemblies.

[0054] Obviously, the above embodiments are only examples for clearly illustrating, and are not limited to the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and cannot be exhausted. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for non-destructive fabrication of multi-element wafer assemblies, wherein the method utilizes the excellent water-soluble adhesive and softening properties of water-soluble epoxy adhesives, making wafer substrate removal simple and easy without damaging the piezoelectric ceramic micropillar electrode surfaces, characterized in that... Using a water-soluble epoxy adhesive as a bonding material between the piezoelectric ceramic and the substrate includes the following steps: Step S1: Surface treatment; roughen and degrease the substrate bonding surface and the piezoelectric ceramic electrode bonding surface respectively; Step S2: Adhesion; Apply water-soluble epoxy adhesive to the bonding surfaces, apply force with clamps, and leave at room temperature for more than 24 hours; Step S3: Cutting; Cut the substrate in the X and Y directions in one step to form an array of piezoelectric ceramic pillars; Step S4: Wash and air dry at room temperature; Step S5: Pre-baking and pouring of polymer decoupling material at a temperature of 45-70℃, vacuuming, wiping off excess decoupling material on the ceramic electrode surface, or scraping off excess decoupling material on the ceramic electrode surface during initial curing, and then heating for curing. Step S6: First, mechanically polish the substrate to a thin layer, then boil it in water to soften the epoxy adhesive and remove the substrate without damage. Step S7: Remove excess particles to form an approximately circular wafer assembly; Step S8: Lead out the positive and negative electrodes.

2. The method for non-destructive fabrication of multi-element wafer assemblies according to claim 1, characterized in that: The hydrolyzed epoxy adhesive of step S2 has a tensile bond strength greater than 10 MPa, a glass transition temperature Tg of 110-130℃, and a Shore D of 75-85.

3. The method for non-destructive fabrication of multi-element wafer assemblies according to claim 1, characterized in that: If the coolant is water during cutting in step S3, then water soaking, rinsing, brushing, or ultrasonic cleaning will be used in step S4; if the coolant is oil during cutting in step S3, then oil soaking or brushing will be used in step S4.

4. The method for non-destructive fabrication of multi-element wafer assemblies according to claim 1, characterized in that: The decoupling material used in step S5 is polyurethane elastomer, epoxy, or silicone rubber.

5. The method for non-destructive fabrication of multi-element wafer assemblies according to claim 1, characterized in that: In step S5, before the initial curing of the injected decoupling material, the previous steps all kept the piezoelectric ceramic at a low temperature.