JPH0329549B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an abrasive material made of synthetic resin, and in particular to an abrasive material that has the ability to generate sharp edges during jetting processing (hereinafter referred to as self-generating ability) and a method for manufacturing the same. Pertains to.

[Technical background of the invention]

For surface treatment of soft metals and deburring of electronic equipment parts, abrasives are accelerated with compressed air and
A method of jet machining by colliding with the workpiece, such as soft metal or electronic device parts, has been adopted. Conventionally, walnut shell powder and apricot shell powder have been used as such abrasives.

[Problems with background technology]

However, vegetable-based walnut shell powder and apricot shell powder have high elasticity and stickiness when dry, so when these are used as abrasives to blast the workpiece, the edges of the abrasives The drawback was that the polishing force was reduced in a short period of time due to rounded edges. In particular, when such an abrasive is applied to remove resin burrs from a semiconductor molded product, the resin burrs present on the lead frame and between the leads of the molded product cannot be sufficiently removed.

[Purpose of the invention]

The present invention aims to provide an abrasive material that can exhibit good abrasive power for a long time when spraying a workpiece, and a method for producing the abrasive material.

[Summary of the invention]

The abrasive material of the present invention is made of synthetic resin particles having cracks that can be cleaved by external force.

The above-mentioned granules have irregularly formed cracks, and due to the impact during the blasting process, they crack along the cracks and fall off, forming new sharp edges. For this reason, it is desirable that the granules be made of a synthetic resin with high hardness and low ductility. Examples of such synthetic resins include thermosetting resins such as epoxy resins, urea resins, and polyester resins, as well as relatively hard thermosetting resins such as acrylic resins.

The synthetic resin granules are desirably structured to have a large number of cutting edges for the purpose of grinding the workpiece and removing resin burrs by jetting with compressed air. Further, the shape of the synthetic resin granules may be arbitrary, such as flat, granular, or acicular, and synthetic resin granules having different shapes may be mixed to form the abrasive.

The size of the synthetic resin granules can be freely selected depending on the use of the abrasive, but for example, when used for removing resin burrs from molded products, the average diameter (the sum of the maximum diameter and minimum diameter of one granule) 1/2) with a peak within the range of 0.05 to 2.0 mm.

The method for manufacturing the abrasive material of the present invention described above includes a method of molding a synthetic resin material and a method of granulating the synthetic resin material, and prevents cracks from occurring when molding and/or granulating the synthetic resin material. It is characterized by allowing Cracks can be generated by molding a synthetic resin material to retain internal strain by thick molding using the exothermic reaction during molding of the thermosetting resin, or by forming the thermosetting resin into granules in advance. (Particle size: 0.05 to 5 mm) A method of dispersing the granules as cores in a synthetic resin and molding them, generating cracks around the cores due to the shrinkage that occurs during molding, and further forming granules.Synthetic resin material is gelled by heating or addition of a catalyst, strained at a stage where hardening is not progressing, and then coarsely pulverized, and during this coarse pulverization, countless cracks occur due to the brittle nature of the molded product at a stage where hardening is not progressing. A method of molding a synthetic resin material at high temperatures (50 to 150°C) to cause a rapid molding reaction, rapidly generating internal strain, and creating countless cracks; , A method of softening the molded product by immersing it in a chemical solution such as methanol or boiling water to generate fine cracks in the molded product, and further generating cracks during pulverization. A method of forcibly generating cracks by turning the granulated material into fine granules, and cooling the coarse granulated material after molding the synthetic resin material to a temperature of 10°C or lower, preferably -20°C or lower, to make it brittle. A method in which the synthetic resin material is made into fine grains in stages, a method in which after molding the synthetic resin material, it is made into coarse grains, and then heated to a high temperature of 150°C or higher to reduce the strength and become fine grains to generate cracks. An appropriate method may be selected, such as a method of generating cracks in the powdered abrasive material by combining at least two or more of the above methods.

Since the abrasive material of the present invention is composed of synthetic resin particles having cracks that can be cleaved by external force, when the abrasive material is accelerated with compressed air and jetted by colliding with the workpiece, the abrasive material collides with the workpiece. The workpiece can be ground or deburred by force, and the impact force during the blasting process easily cracks and falls off along the crack, forming a new sharp edge. Grinding or deburring performance of workpieces can be maintained even after long-term use.

In addition, if an abrasive material is formed by holding a surfactant in the synthetic resin granules, when the workpiece is particularly dry blasted using this abrasive material, it is possible to prevent the generation of electrical charge on the workpiece. This has the effect of simplifying the cleaning process of the workpiece after the blasting process.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on examples.

Example 1 First, unsaturated polyester material Estar R23A
-1 (product name; manufactured by Mitsui Toatsu Chemical Co., Ltd.) as a catalyst
55% MEKPO (Methyl Ethyl Ketone Per.
Added 2% oxide), length x width x height 300mm
Pour into a 300mm x 20mm mold. The unsaturated polyester resin block thus obtained is cut into pellets, which are coarsely crushed using a crusher, hammer, etc., and then the coarse powder is finely crushed using a ball mill, roll mill, impact crusher, etc. We produced unsaturated polyester resin granules having a large number of cutting edges with an average diameter of around 0.7 mm. Next, as shown in Fig. 1, a compressor having a structure in which crushed pieces 3 of a material (for example, diamond), which is much harder than synthetic resin, is held on the opposing surfaces of upper and lower molds 1 and 2 via adhesive layers 4a and 4b. are prepared, and polyester resin granules 6 having a large number of edges 5 made by the above method are loaded between the upper and lower molds 1 and 2, and compressed by the upper and lower molds 1 and 2 to form the crushed pieces 3. The grains 6 that come into contact with... are made into finer grains,
An abrasive material 8 having an average particle diameter of approximately 0.3 mm and having cracks 7 that can be cleaved by external force travel was obtained.

Next, the removal of resin burrs from the semiconductor molded product shown in FIG. 2 using the abrasive material will be explained using the wet blasting apparatus shown in FIG. 3.

After the lead flail with the semiconductor element mounted thereon is housed in a molding mold in advance, epoxy resin is injected into the mold to mold the semiconductor element (not shown) on the lead frame 9 as shown in FIG. resin layer 10
A semiconductor molded product 11 sealed with the above was molded. In this molded product 11, resin burrs 12 were generated on the lead frame 9 near the resin layer 10 and between the leads of the lead frame 9 during molding.

Next, the abrasive material 8 and water 15 are mixed in a ratio of 1:1 into a hopper 14 installed in a pressurizing chamber 13 shown in FIG.
It was accommodated at a ratio of 3. Next, the first pump 1
6 was activated to suck in the abrasives 8 along with water 15, and the abrasives 8 were forcibly fed to the bottom of the hopper 14 for stirring, thereby uniformly dispersing the abrasives 8 to prepare a slurry.

Next, the second pump 17 is operated to suck up the slurry and introduce it into the gun 18, and the slurry is dispersed and accelerated by compressed air from the air introduction pipe 19 to form a three-phase high-speed jet stream 20 of water, abrasive material, and air. The liquid was sprayed toward the aforementioned semiconductor molded product (not shown) that was transported into the processing chamber 13. When the jet stream is injected onto the molded product in this way, as shown in FIG. Resin burr 12
collide with The resin burr 12 is made of thermosetting epoxy resin, and a crack 21 is generated in the resin burr 12 due to the concentrated (local) impact force caused by the relatively brittle edge 5 of the abrasive material 8 and the vibration accompanying the impact force. do. Furthermore, water enters the cracks 21 generated in the resin burr 12 and enters the interface between the lead frame 9 and the resin burr 12, acting to float the resin burr 12 relative to the lead frame 9. Further, the abrasive material 8 having a large number of edges 5 is attached to the resin burr 12.
Since the resin burr 12 collides with the crack 21 many times, the resin burr 12 is completely removed due to the floating action of the resin burr 12 due to the infiltrated water.

Further, since the abrasive material 8 has irregular cracks 7 from the surface toward the inside, the collision with the semiconductor molded product 11 causes the abrasive material 8 to crack along the cracks 7, resulting in rounded edges. It falls off and new sharp edges are formed. As a result, even after long-term use, semiconductor molded products 11
The resin burr 12 removal performance can be maintained.

Therefore, by spraying, for example, a semiconductor molded product 11 using the abrasive material 8 of the present invention, resin burrs 12 on the molded product 11 can be effectively removed, and cracks in the abrasive material 8 can be removed. Resin burrs 1 adhered to minute parts of the molded product 11 (for example, between the leads of the lead frame 9, etc.) due to new sharp edges caused by cracks and falling off along the lines 7...
2 can be completely removed without leaving any residue.

In fact, the test shown below confirmed that the abrasive material of Example 1 had excellent deburring performance. In this test, comparative examples will also be described.

Comparative example Unsaturated polyester material Estar R235A-1
(Product name: Catalyst 55% manufactured by Mitsui Toatsu Chemical Co., Ltd.
MEKPO (methyl ethyl ketone oxide)
Added 2% of, length x width x height 300mm x 300mm x 20mm
Pour into the mold. The synthetic resin block thus obtained was coarsely pulverized using a crusher and a hammer, and then a ball mill, roll mill or impact pulverizer was used to obtain synthetic resin granules having an average particle size of approximately 0.3 mm.

However, when we investigated the deburring performance by removing resin burrs from semiconductor devices using the abrasive material with cracks of Example 1 and the abrasive material with a small number of cracks of the comparative example, we found that The graph shown in Figure 5 was obtained. Here, the test conditions were to deburr a semiconductor device using a wet blasting machine for 24 hours continuously, and then deburr 10,000 pieces.
Out of 1000 sampled workpieces, the percentage of workpieces that have been completely deburred is expressed as a percentage of deburring performance. As is clear from FIG. 5, the abrasive material of Example 1 has a deburring property of almost 100%, whereas the abrasive material of the comparative example has a low deburring property of about 80%, and the abrasive material of the present invention has a deburring property of approximately 80%. It can be seen that the material has excellent deburring properties.

Note that the injection processing using the abrasive material of this example is not limited to the purpose of removing resin burrs from semiconductor molded products as described above, but can also be used to remove resin burrs from general molded products, surface treatment of soft metals, etc. The same applies.

Example 2 Addition of the 55% MEKPO to the Esther R235A-1
Add 2% of
A hardened block is obtained by casting into a mm mold. At this time, the temperature at the center inside the block exceeds 250°C, causing internal strain and causing countless cracks.
The block in which cracks were formed in this manner was coarsely crushed using a crusher or hammer, and then a ball mill, roll mill, or impact crusher was used to obtain an abrasive material containing many cracks with an average particle size of approximately 0.3 mm. . Similar to Example 1, the abrasive material in this example also has significantly improved deburring properties.

Example 3 20 parts of the pulverized material with a particle size of 1 mm or less obtained in Example 2 was mixed with 100 parts of Estar R235A-1 as a core, and then 2 parts of the 55% MEKPO was added to form a mixture with a length x width x height of 300 mm x 300 mm. Pour into a 20mm mold and harden to obtain a block. Then, by applying a thermal shock such as rapid heating, internal strain was induced in the block and numerous cracks were generated. An abrasive containing crack was obtained. Similar to Example 1, the abrasive material in this Example also has significantly improved deburring properties.

Example 4 Adding the 55% MEKPO to the Esther R235A-1
0.3% of the block was added, poured into a mold having the same dimensions as in Example 1, and reacted at around 5°C to form a gel. Immediately, an impact strain was applied to generate cracks in the block. Then, the sufficiently hardened block was prepared in Example 2.
Using the same method as above, an abrasive material containing many cracks with an average particle size of around 0.3 mm was obtained. Similar to Example 1, the abrasive material in this Example also has significantly improved deburring properties.

Example 5 When performing the same molding as in Example 4, the synthetic resin was cured at a temperature of 100 to 150°C to induce internal strain in the block and cause cracks.
Using the same method as in Example 2, an abrasive material containing a large number of cracks with an average particle diameter of around 0.3 mm was obtained. Similar to Example 1, the abrasive material in this Example also has significantly improved deburring properties.

Example 6 A block of the same resin and the same catalyst conditions as in Example 1 was cast into a mold of the same size and molded and cured.
Either heat it to 200℃ and then rapidly cool it to below -10℃, or
Alternatively, after generating cracks in the above block by rapidly heating it from a temperature below -10°C to a temperature of 100 to 200°C, a large number of cracks with an average particle size of around 0.3 mm are generated using the same method as in Example 2. I obtained an abrasive containing . The abrasive material in this example also has significantly improved deburring properties as in the example.

Example 7 A block cast using the same resin and the same catalyst conditions as in Example 1 into a mold of the same size and cured was prepared as Example 2.
The coarsely ground synthetic resin particles were coarsely ground using the same method as above, and the coarsely ground synthetic resin particles were mixed with a chemical solution such as an acetone solution or a methanol solution.
After being immersed for a week, the chemical solution was removed and the material was pulverized to obtain an abrasive material containing many cracks with an average particle size of approximately 0.3 mm. Similar to Example 1, the abrasive material in this Example also has significantly improved deburring properties.

Example 8 A block cast using the same resin and the same catalyst conditions as in Example 1 into a mold of the same size and cured was prepared in Example 2.
Coarsely ground the synthetic resin particles using the same method as in Example 2, cooled the coarsely ground synthetic resin particles to -20°C, and finely ground them using the same method as in Example 2. I got the material. Similar to Example 1, the abrasive material in this Example also has significantly improved deburring properties.

Example 9 Coarsely pulverized in the same manner as in Example 2, the coarsely pulverized synthetic resin particles were heated to 170°C, and at this temperature,
Finely pulverized in the same manner as in Example 2, with an average particle size of
An abrasive material containing many cracks of around 0.3 mm was obtained. Similar to Example 1, the abrasive material in this Example also has significantly improved deburring properties.

The abrasive material of the present invention is not limited to those obtained by the specific manufacturing methods from Example 1 to Example 8, but can be obtained by combining at least two or more of the eight manufacturing methods described above. You may use the abrasive material obtained by

〔Effect of the invention〕

As described in detail above, according to the present invention, when injection processing is performed on workpieces such as semiconductor molded products or other molded products or soft metals in which resin burrs are generated during molding, the workpieces can be sprayed even after long-term use. It is possible to provide an abrasive material having good abrasive power that can maintain resin burr removal or grinding performance, and a method for manufacturing the same.

[Brief explanation of drawings]

Figure 1a is a schematic cross-sectional view of a compressor used for manufacturing an abrasive material according to an embodiment of the present invention, Figure 2 is a plan view of a semiconductor molded product, and Figure 3 is Figure 1a.
FIG. 4 is a cross-sectional view for explaining resin burr removal using an abrasive, and FIG. It is a graph showing deburring properties of one example and a comparative example. DESCRIPTION OF SYMBOLS 1, 2...Mold, 3...Crushed pieces made of superhard material, 5...Edge, 7...Crack, 8...Abrasive material, 9...Lead frame, 11...Semiconductor molded product, 12... ...resin burr, 13...processing room, 14...hopper, 15...water, 16,17...
...Pump, 18...Gun, 21...Crack.

Claims (1)

[Scope of Claims] 1. An abrasive material comprising synthetic resin particles having cracks that can be cleaved by external force. 2. A method for producing an abrasive material comprising a method of molding a synthetic resin material and a method of granulating the synthetic resin material, characterized in that cracks are generated when the synthetic resin material is molded and/or granulated. 3. The method for manufacturing an abrasive material according to claim 2, characterized in that a synthetic resin material that retains internal strain is molded. 4. A method for manufacturing an abrasive material according to claim 2, characterized in that a synthetic resin material is molded using thermosetting resin particles as cores. 5. A method for producing an abrasive material according to claim 2, characterized in that the synthetic resin material is gelled by heating or the addition of a catalyst, and then strain is applied at a stage where hardening has not progressed. 6. The method for manufacturing an abrasive material according to claim 2, characterized in that the synthetic resin material is molded at a high temperature. 7. A method for producing an abrasive material according to claim 2, characterized in that a thermal shock is applied to the synthetic resin material to generate cracks. 8. The method of manufacturing an abrasive material according to claim 2, wherein the synthetic resin material is immersed in a chemical solution after being molded. 9 Granulation of the synthetic resin material is carried out by first making it into coarse particles, then making it into fine particles. 3. The method for producing an abrasive material according to claim 2, wherein the abrasive material is made to 10 The granulation of the synthetic resin material is carried out by first making it into coarse particles and then making it into fine particles, and the above-mentioned coarse particles are made into fine particles at a temperature of 10°C or less. A method for manufacturing an abrasive material according to claim 2. 11 The granulation of the synthetic resin material is carried out by first making it into coarse granules and then making it into fine granules, and the above-mentioned coarse granules are made into fine granules under high temperature conditions with reduced strength. A method for manufacturing an abrasive material according to claim 2.