Cleaning putty and method for cleaning mounted semiconductor parts using same

Abstract

This cleaning putty for cleaning mounted semiconductor parts comprises a millable silicone rubber composition as the main component, has a plasticity of not less than 20 but less than 80 in accordance with JIS K 6300-3:2019 or ISO 2007:1991, and has an adhesion strength of 0.3-4 N with respect to aluminum. This cleaning method in which said cleaning putty is used comprises: pressing the cleaning putty against a printed board that has a silicone-based heat dissipation material coated thereon or attached thereto, and removing the cleaning putty from the printed board to clean mounted semiconductor parts. Accordingly, provided are: a cleaning putty that has imparted thereto putty characteristics which prevent damage to parts by selectively sticking to a silicone material without sticking to a substrate or wires, and which allow the cleaning putty to infiltrate minute gaps; and a method for cleaning mounted semiconductor parts using the cleaning putty.

Description

Cleaning putty and method for cleaning semiconductor mounted components using the same

[0001] The present invention relates to a cleaning putty and a method for cleaning semiconductor mounted components using the same.

[0002] Fine dust particles are often generated during the manufacturing process of printed circuit boards equipped with semiconductor elements such as CPUs (central processing units) and GPUs (graphics processing units). Furthermore, fine dust particles can be generated when mounting thermally conductive grease or thermally conductive putty, which are heat dissipation materials for electronic components, on electronic components. If this fine dust is not removed, the product will be rejected, resulting in a decrease in product yield. Furthermore, these heat dissipation materials must be removed when repairing or reapplying them. Insufficient removal can result in problems such as reduced heat dissipation and contamination due to detachment. Patent Document 1 proposes a silicone-based pressure-sensitive adhesive with a specific gel fraction and a specific degree of swelling in toluene. Patent Document 2 proposes a silicone-based pressure-sensitive adhesive with pores or cracks. Patent Document 3 proposes an addition reaction curing type silicone-based pressure-sensitive adhesive.

[0003] Japanese Patent No. 6626125 Japanese Patent Application Laid-Open No. 2004-123760 Japanese Patent Application Laid-Open No. 2004-091703

[0004] However, conventional adhesives adhere to the board and the leads on it, which can damage the components. Also, wiping with a cloth is not enough to clean the tiny gaps between the leads, so a needle is required to scrape them out, which takes a lot of time.

[0005] To solve the above-mentioned conventional problems, the present invention provides a cleaning putty that does not adhere to the substrate or leads but selectively adheres to a silicone material, thereby preventing damage to components, and that has putty properties that enable it to penetrate into minute gaps, and a method for cleaning semiconductor mounted components using the same.

[0006] One embodiment of the present invention relates to a cleaning putty for cleaning semiconductor mounted components, which has a millable silicone rubber composition as its main component, has a plasticity of 20 or more but less than 80 according to JIS K 6300-3:2019 and ISO 2007:1991, and has an adhesive strength to aluminum of 0.3 N or more but 4 N or less.

[0007] Another embodiment of the present invention relates to a method for cleaning semiconductor-mounted components using the cleaning putty, which involves pressing the cleaning putty against a printed circuit board to which a silicone-based heat dissipation material has been applied or attached, and then peeling it off to clean the semiconductor-mounted components.

[0008] The present invention provides a cleaning putty that uses a millable silicone rubber composition as its main component, has a plasticity of 20 or more but less than 80 according to JIS K 6300-3:2019 and ISO 2007:1991, and has an adhesive strength to aluminum of 0.3 N or more but less than 4 N. This putty does not adhere to substrates or leads, but instead selectively adheres to silicone materials, preventing damage to components. Furthermore, by imparting putty properties that enable it to penetrate into minute gaps, it is possible to provide a cleaning putty that can significantly reduce the time and labor required for cleaning, and a method for cleaning semiconductor-mounted components using the putty.

[0009] Fig. 1 is a schematic cross-sectional view of a semiconductor package according to one embodiment of the present invention. Fig. 2 is a schematic perspective view of a cleaning putty according to one embodiment of the present invention. Fig. 3 is a schematic perspective view of a cleaning putty according to another embodiment of the present invention.

[0010] The present invention provides a cleaning putty for cleaning semiconductor-mounted components. The semiconductor-mounted components include printed circuit boards equipped with semiconductor elements such as CPUs (central processing units) and GPUs (graphics processing units). The cleaning putty of the present invention is primarily composed of millable silicone rubber. Millable silicone rubber is a solid type of silicone rubber, primarily composed of a linear polymer with a degree of polymerization of 3,000 to 10,000, blended with various additives such as silica-based reinforcing fillers, lubricants, and colorants, and cured by heat using a vulcanizing agent, resulting in a clay-like state. This millable silicone rubber is used to adjust the plasticity and adhesiveness for excellent workability. In the above, the primary component preferably comprises 40% or more by weight of the millable silicone rubber relative to 100% by weight of the cleaning putty. The upper limit is 100% by weight. Within the above range, organopolysiloxanes other than the millable silicone rubber may also be included. Furthermore, the millable silicone rubber may be uncrosslinked.

[0011] The cleaning putty of the present invention has a plasticity according to JIS K 6300-3:2019 and ISO 2007:1991 of 20 or more and less than 80, preferably 20 or more and 75 or less, and more preferably 20 or more and 70 or less. When the plasticity is within the above range, the putty is soft, has good conformability, and easily penetrates into fine gaps. If the plasticity is less than 20, the putty is too soft and easily tears and remains between the leads, while if the plasticity is 80 or more, the putty becomes hard and has difficulty penetrating between the leads, which is undesirable.

[0012] The cleaning putty of the present invention has an adhesive strength (tackiness) to aluminum of 0.3 N or more and 4 N or less, preferably 0.4 N or more and 3.8 N or less, and more preferably 0.5 N or more and 3.6 N or less. When the adhesive strength (tackiness) is within the above range, the putty does not adhere to the substrate or leads, but instead adheres selectively to the silicone material, thereby preventing damage to components. Furthermore, the putty is less likely to damage leads, etc.

[0013] When the cleaning putty is pressed against an aluminum block and then peeled off, it is preferable that no trace of interfacial destruction remains on the aluminum block side.Furthermore, when the cleaning putty is pressed against a printed circuit board or silicone rubber and then peeled off, it is preferable that no trace of interfacial destruction remains on the printed circuit board side but on the silicone rubber side.This allows for efficient cleaning.

[0014] The cleaning putty preferably further contains an organopolysiloxane containing a boric acid compound, which prevents damage to components by selectively adhering to silicone materials without adhering to substrates or leads, and allows the putty to penetrate into minute gaps.

[0015] When a heat dissipating material made of a liquid thermally conductive silicone composition is applied to a printed circuit board so that it is 10 mm long, 20 mm wide, and 0.3 mm thick, the mass is measured, and the cleaning putty is pressed against it and then peeled off, the removal rate for the first time is preferably 60 mass% and the removal rate for the second time is preferably 85 mass% or more. This makes it possible to produce a putty that does not adhere to the board or leads but instead selectively adheres to the silicone material, preventing damage to components and allowing it to penetrate into minute gaps.

[0016] The cleaning putty of the present invention is preferably formed into a tape, sheet, rod or block shape, which allows it to clean various types of semiconductor mounted components.

[0017] The method for cleaning semiconductor-mounted components of the present invention involves pressing the cleaning putty onto a printed circuit board coated or adhered with a silicone-based heat dissipation material and then peeling it off to clean the semiconductor-mounted components. This has the following advantages: (1) Improved workability, such as reduced stickiness to hands, prevention of damage to components on the board, and ability to cover large areas, makes handling easier and allows for quick and easy removal of material that has gotten into narrow spaces. (2) Because it blends well with silicone, it can absorb liquid TIM simply by pressing it. (3) Because it is in the form of a soft putty, it can easily clean gaps less than 1 mm, such as gaps between leads. (4) Because it can be pressed over a large area, it can clean a wide range of uneven electronic components at once. (5) It does not adhere to the board material and can only adhere and remove the silicone material.

[0018] The following description will be given with reference to the drawings. Figure 1 is a schematic cross-sectional view of a semiconductor package 1 according to one embodiment of the present invention. This semiconductor package 1 has an IC chip 3 mounted on a printed circuit board 2, and the printed circuit board 2 and IC chip 3 are electrically connected by leads 4 and gold wires 5, with the IC chip 3 being sealed with sealing resin 6. There are gaps 7a and 7b between the printed circuit board 2, leads 4, and sealing resin 6, and these gaps will be cleaned as an example.

[0019] Fig. 2 is a schematic perspective view of cleaning putty 8 according to one embodiment of the present invention. This cleaning putty 8 is tape-shaped overall, with a tip that is 2 mm thick. Fig. 3 is a schematic perspective view of cleaning putty 9 according to another embodiment of the present invention. This cleaning putty 9 has three grooves 10a, 10b, and 10c formed in the tip to increase the contact area with dust. Because the cleaning putty of the present invention is soft, it can be molded into any shape, including common tape, sheet, rod, or block shapes.

[0020] The present invention will be described below using examples, but is not limited to these examples.

[0021] Various parameters were measured using the following methods. <Hardness (Plasticity)> Hardness (plasticity) was measured using a Wallace Rapid Plastometer in accordance with JIS K 6300-3 and ISO 2007:1991. The sample was compressed between two metal plates at a constant load (300 N) for a constant time (15 seconds) to a constant thickness (1 mm) at a measurement temperature of 23°C. The sample was then further compressed at a constant load (100 N) for a constant time (15 seconds) and the resulting thickness (t) was multiplied by 100. A smaller value indicates greater flexibility. <Aluminum Plate Adhesion Strength (Tackiness)> Measurements were made using an HTC-1 Tackiness Checker (manufactured by Toyo Seiki Co., Ltd.). The contacts were pressed against the target object at the following pressures and times, and the stress during peeling was detected using a load cell system. In the following examples, the pressure of the tackiness checker (manufactured by Toyo Seiki Co., Ltd.) was 10 N, the time was 6 seconds, and the contacts were aluminum F-rings. <Interfacial failure from printed circuit board and silicone rubber> A general printed circuit board with solder resist processing was used as the printed circuit board material. A 1 mm thick silicone rubber sheet was used as the silicone rubber. Measurement method: (1) Press the sample against each material. (2) Peel the sample off and evaluate according to the following criteria. No: No sample remains on each material. Present (small): Some sample remains. Present (large): Most of the sample remains. <SPG-30B cleaning test> (SPG-30B is the name of a thermally conductive silicone product manufactured by Fuji Polymer Industries Co., Ltd.) Measurement method: (1) Apply SPG-30B to a general solder resist-processed board so that it is 10 mm long, 20 mm wide, and 0.3 mm thick, and measure the weight. (2) Press the sample against the SPG so that it covers the SPG. (3) The sample is then peeled off and the remaining weight of the SPG is measured (first time). (4) A new surface of the sample is pressed against the sample again, and the remaining weight of the SPG is measured (second time). (5) The rate of change from the initial weight is calculated and this is the removal rate.

[0022] (Example 1) - 100 g of an uncrosslinked millable type silicone rubber composition containing diorganopolysiloxane and a boric acid compound, product name "KE-1614H-U" manufactured by Shin-Etsu Chemical Co., Ltd. - 8 g of a polyorganosiloxane base polymer, product name "CF3110" manufactured by Toray Dow Corning Silicone Co., Ltd. The above ingredients were uniformly mixed to prepare a cleaning putty.

[0023] (Example 2) - 100 g of an uncrosslinked millable type silicone rubber composition containing diorganopolysiloxane and a boric acid compound, product name "KE-1614H-U" manufactured by Shin-Etsu Chemical Co., Ltd. - 20 g of a polyorganosiloxane base polymer, product name "CF3110" manufactured by Toray Dow Corning Silicone Co., Ltd. The above ingredients were uniformly mixed to prepare a cleaning putty.

[0024] (Example 3) - 100 g of an uncrosslinked millable type silicone rubber composition containing diorganopolysiloxane and a boric acid compound, trade name "KE-1614H-U" manufactured by Shin-Etsu Chemical Co., Ltd. - 37 g of a polyorganosiloxane base polymer, trade name "CF3110" manufactured by Toray Dow Corning Silicone Co., Ltd. The above ingredients were mixed uniformly to prepare a cleaning putty.

[0025] (Example 4) - Toray Dow Corning Silicone Co., Ltd., product name "DAWSIL CF 9306": 100 g of a millable type silicone rubber composition containing organopolysiloxane, silica, cristobalite, quartz, and diatomaceous earth - Shin-Etsu Chemical Co., Ltd., product name "X-93-1169": 5 g of an organopolysiloxane additive containing a boric acid compound - Toray Dow Corning Silicone Co., Ltd., product name "CF3110": 20 g of a polyorganosiloxane base polymer The above ingredients were mixed uniformly to prepare a cleaning putty.

[0026] Example 5 100 g of a millable type silicone rubber composition, trade name "XIAMETER SE 1185 U" manufactured by Toray Dow Corning Silicone Co., Ltd., was used as a cleaning putty.

[0027] (Example 6) - 100 g of millable type silicone rubber composition, trade name "XIAMETER SE 1185 U", manufactured by Toray Dow Corning Silicone Co., Ltd. - 5 g of organopolysiloxane additive containing a boric acid compound, trade name "X-93-1169", manufactured by Shin-Etsu Chemical Co., Ltd. The above ingredients were mixed uniformly to prepare a cleaning putty.

[0028] Comparative Example 1 100 g of an uncrosslinked millable type silicone rubber composition containing diorganopolysiloxane and a boric acid compound, trade name "KE-1614H-U" manufactured by Shin-Etsu Chemical Co., Ltd., was used as a cleaning putty.

[0029] (Comparative Example 2) - 100 g of an uncrosslinked millable type silicone rubber composition containing diorganopolysiloxane and a boric acid compound, trade name "KE-1614H-U" manufactured by Shin-Etsu Chemical Co., Ltd. - 74 g of a polyorganosiloxane base polymer, trade name "CF3110" manufactured by Toray Dow Corning Silicone Co., Ltd. The above ingredients were uniformly mixed to prepare a cleaning putty.

[0030] (Comparative Example 3) - 100 g of a millable type silicone rubber composition containing organopolysiloxane, silica, cristobalite, quartz, and diatomaceous earth, manufactured by Dow Corning Toray Silicone Co., Ltd. - 20 g of a polyorganosiloxane base polymer, manufactured by Dow Corning Toray Silicone Co., Ltd. The above ingredients were mixed uniformly to prepare a cleaning putty.

[0031] Comparative Example 4 A cleaning putty was prepared using a silicone adhesive containing, as the main component, "DOWSIL SH 4280" (a peroxide-curing adhesive) manufactured by Toray Dow Corning Silicone Co., Ltd.

[0032] Comparative Example 5 A gel sheet using acrylic resin, trade name "SARCON NR-c" manufactured by Fuji Polymer Industries, was kneaded into a putty form and used to prepare a cleaning putty.

[0033] The above conditions and results are summarized in Tables 1 and 2.

[0034]

[0035]

[0036] The following is clear from Tables 1 and 2. (1) Examples 1 to 3 and Comparative Examples 1 and 2 compare the range of hardness (plasticity). While Examples 1 to 3 were all favorable, Comparative Example 1 was too hard and did not penetrate between the leads, and Comparative Example 2 was too soft, easily torn, and easily remained between the leads. (2) The addition of a boric acid compound improved the performance of Examples 4 and 6 in the SPG30B cleaning test compared to Comparative Examples 3 and 5, respectively. (3) Comparative Example 4 used a silicone-based adhesive primarily composed of a peroxide-curing adhesive, but was undesirable due to high interfacial failure with the substrate and silicone rubber. (4) Comparative Example 5 was a putty made by refining a gel sheet using acrylic resin. However, its adhesive strength with aluminum was too high, it was prone to tearing, and its performance in the SPG30B cleaning test was poor. Furthermore, the cleaning putties of Examples 1 to 6 of the present invention also demonstrated the following effects. (1) The cleaning putties of Examples 1 to 6 can be used to clean flat surfaces by simply pressing the putty against the surface and peeling it off, resulting in good handling and work efficiency. (2) The gaps in the lead parts are approximately 0.3 to 0.5 mm. With conventional methods (e.g., commercially available tissue paper, Kimberly-Clark Corporation, product name "Kimwipe") and the cleaning putties of Comparative Examples 1 to 5, dust embedded in the lead parts is difficult to remove and must be removed with a needle. However, the cleaning putties of Examples 1 to 6 can be used to clean even narrow areas by simply pressing the putty against the surface and peeling it off, resulting in good handling and work efficiency. (3) Repairs are required due to application errors or after being rotated in an environment of approximately 70°C. These repairs can also be achieved by simply pressing the putty against the surface and peeling it off, resulting in good handling and work efficiency.

[0037] The cleaning putty of the present invention is suitable for cleaning semiconductor mounted components.

[0038] REFERENCE SIGNS LIST 1 Semiconductor mounted component 2 Printed circuit board 2 3 IC chip 4 Lead wire 5 Gold wire 6 Sealing resin 7a, 7b Gap 8, 9 Cleaning putty 10a, 10b, 10c Groove

Claims

1. A cleaning putty for cleaning semiconductor mounted components, characterized in that the main component is a millable type silicone rubber composition, the plasticity according to JIS K 6300-3:2019 and ISO 2007:1991 is 20 or more and less than 80, and the adhesive strength to aluminum is 0.3 N or more and 4 N or less.

2. The cleaning putty according to claim 1, wherein when the cleaning putty is pressed against an aluminum block and then peeled off, no trace of interfacial destruction remains on the aluminum block.

3. The cleaning putty according to claim 1 or 2, which is pressed against a printed circuit board or silicone rubber and then peeled off, leaving no trace of interfacial destruction on the printed circuit board side but on the silicone rubber side.

4. A cleaning putty according to any one of claims 1 to 3, wherein the Millable type silicone rubber is present in an amount of 40% by mass or more and 100% by mass or less relative to 100% by mass of the cleaning putty.

5. The cleaning putty according to any one of claims 1 to 4, further comprising an organopolysiloxane containing a boric acid compound.

6. The cleaning putty according to any one of claims 1 to 5, further comprising an organopolysiloxane other than the millable silicone rubber.

7. A cleaning putty according to any one of claims 1 to 6, wherein the millable type silicone rubber composition contains uncrosslinked millable type silicone rubber.

8. A cleaning putty according to any one of claims 1 to 7, wherein a heat dissipating material of a liquid thermally conductive silicone composition is applied to a printed circuit board so as to be 10 mm long, 20 mm wide and 0.3 mm thick, the mass is measured, and the cleaning putty is pressed against the board and then peeled off; the removal rate for the first time is 60 mass% and the removal rate for the second time is 85 mass% or more.

9. The cleaning putty according to any one of claims 1 to 8, which is formed into a tape, sheet, rod or block shape.

10. A method for cleaning semiconductor-mounted components using the cleaning putty according to any one of claims 1 to 9, characterized in that the cleaning putty is pressed against a printed circuit board to which a silicone-based heat dissipation material has been applied or attached, and then peeled off to clean the semiconductor-mounted components.

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