Chip underfilling method for reducing glue residue
By applying photoresist on the chip's readout circuit, performing underfill dispensing, removing photoresist and plasma cleaning, the problem of glue residue in the chip's underfill process is solved, efficient removal of glue residues and improving the performance of chip products.
Patent Information
- Application Number
- CN202411925118.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2025-04-04
AI Technical Summary
In the existing chip underfill process, the glue residue problem is difficult to effectively solve, resulting in the cured glue falling off during subsequent processing, affecting product performance.
Coat the photoresist on the readout circuit that does not affect the underfill, cure and perform underfill on the dispensing. Then use a spray gun to remove the photoresist and pass through plasma cleaning to remove excess dispensing glue.
This greatly reduces glue residue, improves the performance of chip products, avoids the impact of glue peeling on product performance, and does not have an adverse effect on the appearance of the readout circuit and the performance of the underfill glue.
Smart Images
Figure CN119764189A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of chip preparation, and in particular relates to a chip bottom filling method for reducing glue residue. Background Art
[0002] The bottom mounting technology of the chip is the main way to interconnect the chip with the terminal. In order to prevent the stress difference between the chip and the substrate from causing the welding solder ball to break, it is often necessary to do a bottom glue filling process between the chip and the substrate. At present, the process of chip bottom filling is to drop epoxy glue on the edge of the readout circuit. The glue will flow into the inside of the chip through capillary action and fill the bottom between the chip and the substrate. However, in the existing bottom filling process, after the filling is completed, there will be glue residue on the edge of the readout circuit. The solidified glue will fall off during the subsequent processing and affect the product performance. There are currently two main methods for removing chip glue residue. The first method is to manually use a blade to scrape off the solidified glue on the edge. The problem with this method is that the blade is too sharp and may scratch the end face of the chip and the substrate. Because both ends need to be cleaned, the chip is small in size and the operation is difficult and inefficient. The second method is to use a grinder for grinding, but the chip is held close to the grinder for grinding and removing the glue. This method is not only unsafe, but also very labor-intensive. At the same time, since the chip cannot be accurately fixed by hand, the grinding accuracy is difficult to guarantee, and it is even easy to damage the chip itself. Summary of the invention The purpose of the present invention is to provide a chip bottom filling method for reducing glue residue, which can significantly reduce glue residue and improve the performance of chip products.
[0003] The present invention provides a chip bottom filling method for reducing glue residue, which adopts the following technical scheme: A chip bottom filling method for reducing glue residue comprises the following steps: (1) Determine the bottom filling dispensing position of the chip, apply photoresist on the readout circuit that does not affect the bottom filling, and after curing, obtain a chip containing photoresist; (2) dispensing glue on the chip containing the photoresist at the dispensing position determined in step (1), and drying after bottom filling to obtain the bottom-filled chip; (3) Using a spray gun to spray the surface of the bottom-filled chip (to remove the photoresist) to obtain a chip with the photoresist removed; then the chip with the photoresist removed is plasma cleaned, and oxygen is introduced during the plasma cleaning (to remove excess glue), to obtain a bottom-filled chip with the glue residue removed.
[0004] In the present invention, photoresist is coated on the readout circuit that does not affect the bottom filling, which can reduce the contamination range of the glue dispenser, thereby reducing the oxygen permeation time of subsequent plasma cleaning and avoiding excessively long oxygen permeation time affecting the performance of the bottom filling glue.
[0005] Preferably, in the step (1), the readout circuit that does not affect the colloid bottom filling is the readout circuit other than the glue dispensing position and the readout circuit on the side opposite to the glue dispensing position.
[0006] In the step (1), before determining the bottom filling dispensing position of the chip, the chip is first cleaned; the cleaning is carried out by plasma cleaning.
[0007] The plasma cleaning in the present invention can clean impurities on the chip surface, enhance material wettability, increase the glue diffusion area, and reduce the thickness of residual glue on the readout circuit, thereby reducing the subsequent oxygen supply time.
[0008] Preferably, in step (1), the curing temperature is 90-110° C. and the curing time is 10-15 min.
[0009] Preferably, in step (2), the amount of glue dispensed is 0.4-0.5 mg, and the glue dispensed range is 1 / 2-2 / 3 of the side length of the chip.
[0010] Preferably, in step (2), the filling temperature is 55-65°C; the drying temperature is 75-85°C, and the drying time is 14-16 hours.
[0011] Preferably, in step (3), the spray gun is an alcohol spray gun; and the spraying time of the spray gun is 1 to 2 minutes.
[0012] Preferably, in step (3), the plasma cleaning time is 15 to 20 minutes.
[0013] The above one or more technical solutions of the present invention can achieve at least one of the following beneficial effects: In the method of the present invention, photoresist is coated on the readout circuit that does not affect the bottom filling, which can reduce the contamination of the readout circuit by the glue dispenser, thereby reducing the subsequent oxygen permeation time and avoiding the influence of too long oxygen permeation time on the bottom filling glue in the chip.
[0014] The method of the present invention can completely remove the residual glue dispensed on the readout circuit, and prevent the cured glue from falling off during the subsequent processing and affecting the product performance.
[0015] The method of the present invention will not have a bad influence on the appearance of the readout circuit, and will not affect the performance of the bottom filling glue. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 Schematic diagram of the chip and substrate structure.
[0017] Figure 2 This is an optical microscope image of the bottom-filled chip after removing glue residue in Example 1.
[0018] Figure 3 This is an optical microscope image of the bottom filling chip in Comparative Example 1.
[0019] Figure 4 This is an optical microscope image of the bottom-filled chip from which the adhesive was removed in Comparative Example 2.
[0020] Figure 5 This is an optical microscope image of the bottom-filled chip after removing glue residue in Example 2.
[0021] Figure 6 This is an optical microscope image of the bottom-filled chip after removing glue residue in Example 3. DETAILED DESCRIPTION
[0022] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments. Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.
[0023] The schematic diagram of the structure of the chip and substrate of the present invention is as follows Figure 1 As shown, the chip is flip-chip soldered to the middle of the substrate, and the substrate contains readout circuits around the chip.
[0024] Example 1 The chip used in this embodiment is a mercury cadmium telluride focal plane detector chip, and the specific method of chip bottom filling is as follows: (1) Use a plasma cleaner to clean the HgCdTe focal plane detector chip to remove impurities on the chip surface. After cleaning, determine the glue dispensing position. Figure 1 As shown; a photoresist is coated on the readout circuit except for the readout circuit on one side of the dispensing position and the readout circuit on the opposite side of the dispensing position. The coating position of the photoresist is as shown in Figure 1 As shown; after coating, bake at 100°C for 10 minutes to solidify the photoresist to obtain a chip containing photoresist.
[0025] (2) Using a fully automatic glue dispensing machine, dispense glue on the chip containing photoresist at the glue dispensing position determined in step (1), wherein: glue model: 360 (manufacturer: EPO-TEK), glue dispensing amount: 0.48 mg, glue dispensing range: 2 / 3 of the chip side length, after dispensing, bottom fill glue at 60°C, after filling, bake at 80°C for 15h to solidify the bottom fill glue, and obtain a bottom fill chip.
[0026] (3) Use an alcohol spray gun to spray the surface of the bottom-filled chip for 2 minutes to remove the photoresist on the readout circuit, thereby obtaining a chip with the photoresist removed; then place the chip with the photoresist removed into a plasma cleaning device for plasma cleaning for 20 minutes, introducing oxygen during cleaning to remove the residual glue on the edge of the circuit. After cleaning, a bottom-filled chip with the glue residue removed is obtained.
[0027] The optical microscope view of the bottom filling chip after removing the glue residue prepared in this embodiment is as follows: Figure 2 As shown, it can be seen that there is no obvious glue residue on the surface of the underfill chip after removing the glue residue prepared in this embodiment.
[0028] Comparative Example 1 The chip used in this comparative example is a mercury cadmium telluride focal plane detector chip, and its bottom filling process is: A plasma cleaner was used to clean the HgCdTe focal plane detector chip to remove impurities on the chip surface. After cleaning, the dispensing position was determined, and a fully automatic dispensing machine was used to dispense glue on the chip at the dispensing position. The glue model was 360 (manufacturer: EPO-TEK), the dispensing amount was 0.48 mg, and the dispensing range was 2 / 3 of the chip side length. After dispensing, the bottom was filled with glue at 60°C. After filling, it was baked at 80°C for 15 hours to solidify the filled glue to obtain a bottom-filled chip.
[0029] The optical microscope image of the chip surface filled with the bottom in this comparative example is as follows Figure 3 As shown, it can be seen that there are a lot of colloid residues on the chip after bottom filling.
[0030] Comparative Example 2 The method is basically the same as Example 1, except that the photoresist coating in step (1) is not performed. The specific steps are as follows: The chip used in this comparative example is a HgCdTe focal plane detector chip, and its bottom filling process can be seen in Figure 2 , the specific method is as follows: (1) Use a plasma cleaner to clean the HgCdTe focal plane detector chip to remove impurities on the chip surface. After cleaning, determine the location of glue dispensing; use a fully automatic glue dispensing machine to dispensing glue at the determined location (the location of glue dispensing is as follows: Figure 1As shown in the figure, glue is dispensed on the chip, where: glue model: 360 (manufacturer: EPO-TEK), glue amount is 0.48 mg, glue dispensing range is 2 / 3 of the chip side length, after glue dispensing, the bottom is filled with glue at 60°C, after filling, it is baked at 80°C for 15h to solidify the filled glue, and a bottom-filled chip is obtained.
[0031] (2) The bottom-filled chip is placed in a plasma cleaning device and plasma cleaned for 20 minutes. Oxygen is introduced during cleaning to remove the glue remaining on the edge of the circuit, thereby obtaining a bottom-filled chip with glue removed.
[0032] The optical microscope image of the bottom-filled chip after the glue removal in this comparative example is as follows: Figure 4 As shown, the bottom filling chip after the glue removal in this comparative example has some traces of glue residue.
[0033] It can be seen from the optical microscope observation results of Example 1, Comparative Example 1 and Comparative Example 2 that in Comparative Example 1, the residual colloid is not removed, and a large amount of colloid residues will be left on the surface of the corresponding chip. Although plasma oxygen cleaning is used to remove the colloid residue in Comparative Example 2, the colloid residue is too large to completely remove the colloid on the chip. In Example 1, photoresist is coated on the readout circuit that does not affect the bottom filling process, which reduces the colloid residue. Therefore, the residual colloid can be completely removed by plasma oxygen cleaning, and there is basically no colloid residue.
[0034] Example 2 The chip used in this embodiment is a mercury cadmium telluride focal plane detector chip, and the specific method of chip bottom filling is as follows: (1) Use a plasma cleaner to clean the HgCdTe focal plane detector chip to remove impurities on the chip surface. After cleaning, determine the glue dispensing position. Figure 1 As shown; a photoresist is coated on the readout circuit except for the readout circuit on one side of the dispensing position and the readout circuit on the opposite side of the dispensing position. The coating position of the photoresist is as shown in Figure 1 As shown; after coating, bake at 90°C for 15 minutes to solidify the photoresist to obtain a chip containing photoresist.
[0035] (2) Using a fully automatic glue dispensing machine, dispense glue on the chip containing photoresist at the glue dispensing position determined in step (1), wherein: glue model: 360 (manufacturer: EPO-TEK), glue dispensing amount is 0.5 mg, and glue dispensing range is 2 / 3 of the chip side length. After glue dispensing, fill the bottom with glue at 55°C. After filling, bake at 85°C for 14 hours to solidify the filled glue, thereby obtaining a bottom-filled chip.
[0036] (3) Use an alcohol spray gun to spray the surface of the bottom-filled chip for 2 minutes to remove the photoresist on the readout circuit, thereby obtaining a chip with the photoresist removed; then put the chip with the photoresist removed into a plasma cleaning device for plasma cleaning for 18 minutes. During the cleaning, oxygen is introduced to remove the residual glue on the edge of the circuit. After the cleaning is completed, a bottom-filled chip with the glue residue removed is obtained.
[0037] The optical microscope view of the bottom filling chip after removing the glue residue prepared in this embodiment is as follows: Figure 5 As shown, it can be seen that there is no obvious glue residue on the surface of the underfill chip after removing the glue residue prepared in this embodiment.
[0038] Example 3 The chip used in this embodiment is a mercury cadmium telluride focal plane detector chip, and its bottom filling process can be seen in Figure 2 , the specific method is as follows: (1) Use a plasma cleaner to clean the HgCdTe focal plane detector chip to remove impurities on the chip surface. After cleaning, determine the location of the glue dispenser, such as Figure 1 The dispensing position is shown; the photoresist is applied on the readout circuit except the readout circuit on the side of the dispensing position and the side opposite to the dispensing position. Figure 1 As shown; after coating, bake at 110°C for 10 minutes to solidify the photoresist to obtain a chip containing photoresist.
[0039] (2) Use a fully automatic glue dispensing machine to dispense glue on the chip containing photoresist at the glue dispensing position determined in step (1), where: glue model: 360, glue dispensing amount: 0.4 mg, glue dispensing range: 1 / 3 of the chip side length. After dispensing, fill the bottom with glue at 65°C. After filling, bake at 75°C for 16 hours to solidify the filled glue, thereby obtaining a bottom-filled chip.
[0040] (3) Use an alcohol spray gun to spray the surface of the bottom-filled chip for 1 minute to remove the photoresist on the readout circuit, thereby obtaining a chip with the photoresist removed; then put the chip with the photoresist removed into a plasma cleaning device for plasma cleaning for 15 minutes. During the cleaning, oxygen is introduced to remove the residual glue on the edge of the circuit. After the cleaning is completed, a bottom-filled chip with the glue residue removed is obtained.
[0041] The optical microscope view of the bottom filling chip after removing the glue residue prepared in this embodiment is as follows: Figure 6 As shown, it can be seen that there is no obvious glue residue on the surface of the underfill chip after removing the glue residue prepared in this embodiment.
[0042] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.
Claims
1. A chip bottom filling method for reducing glue residue, characterized in that: The following steps are involved: (1) Determine the bottom filling dispensing position of the chip, apply photoresist on the readout circuit that does not affect the bottom filling, and after curing, obtain a chip containing photoresist; (2) dispensing glue on the chip containing the photoresist at the dispensing position determined in step (1), and drying after bottom filling to obtain the bottom-filled chip; (3) Using a spray gun to spray the surface of the bottom-filled chip, a chip with the photoresist removed is obtained; then the chip with the photoresist removed is plasma cleaned, and oxygen is introduced during the plasma cleaning to obtain a bottom-filled chip with glue residue removed.
2. The chip bottom filling method for reducing glue residue according to claim 1, characterized in that: In the step (1), the readout circuits that do not affect the bottom filling are readout circuits other than the glue dispensing position and the readout circuits on the side opposite to the glue dispensing position.
3. The chip bottom filling method for reducing glue residue according to claim 1 or 2, characterized in that: In the step (1), before determining the bottom filling dispensing position of the chip, the chip is first cleaned.
4. The chip bottom filling method for reducing glue residue according to claim 3, characterized in that: The cleaning is performed by plasma cleaning.
5. The chip bottom filling method for reducing glue residue according to claim 1 or 2, characterized in that: In the step (1), the curing temperature is 90-110° C. and the curing time is 10-15 min.
6. The chip bottom filling method for reducing glue residue according to claim 1, characterized in that: In the step (2), the amount of glue dispensed is 0.4-0.5 mg, and the glue dispense range is 1 / 2-2 / 3 of the length of the chip side.
7. The chip bottom filling method for reducing glue residue according to claim 1 or 6, characterized in that: In the step (2), the bottom filling temperature is 50-60°C.
8. The chip bottom filling method for reducing glue residue according to claim 1 or 6, characterized in that: In the step (2), the drying temperature is 80-90° C. and the drying time is 14-16 hours.
9. The chip bottom filling method for reducing glue residue according to claim 1, characterized in that: In the step (3), the spray gun is an alcohol spray gun; and the spraying time of the spray gun is 1 to 2 minutes.
10. The chip bottom filling method for reducing glue residue according to claim 1, characterized in that: In the step (3), the plasma cleaning time is 15 to 20 minutes.