JPH0368067B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a silica-filled resin composition used as a sealant for electronic components. [Prior Art/Disadvantages] It is known to add a silica filler to a resin molded body to improve mechanical strength, heat resistance, dimensional stability, cost reduction, etc. When this resin is used as a sealant for electronic components, it is necessary to dissipate the heat generated by the electronic components to the outside through the resin. In addition, low thermal expansion is required to maintain the normal state of electronic circuits. Silica fillers are generally pulverized into fine particles. For this reason, the particles are angular, resulting in poor dispersibility in the resin and fluidity of the resin. Furthermore, the mold for obtaining the molded body is subject to severe wear. As a countermeasure to this problem, the above-mentioned drawback is solved by using 30 to 80% by weight of the thermosetting resin of spherical silica particles with an average particle size of 1 to 60 μm obtained by passing the filler through a high-temperature flame and melting it. This is known, for example, from Japanese Patent Application Laid-open No. 138740/1983. However, when only these spherical silica particles were used as a filler, the viscosity of the resin was too low, causing a new drawback in that they entered the gaps in the mold during molding, resulting in significant burrs. [Object of the Invention] The object of the present invention is to take advantage of the characteristics of spherical silica grains and at the same time prevent the occurrence of burrs, which is a drawback thereof. [Means for solving the problem] The present invention uses a filler consisting of 55 to 85% by weight of spherical silica particles and 15 to 45% by weight of crushed silica particles with an average particle size of 5 to 50 μm obtained by passing through a high-temperature flame. , a silica-filled resin composition for encapsulants that does not generate burrs and contains 50 to 80% by weight of the thermosetting resin. This resin composition utilizes the characteristics of spherical silica particles while preventing the generation of burrs, which is a drawback thereof, by using crushed silica particles in combination. Therefore, compared to the conventional method, the effects are extremely large, such as a reduction in material costs and a reduction in the number of man-hours required for removing burrs. In addition, since the filler is spherical and highly fluid, the amount of filling into the resin increases, and the thermal conductivity of the resin improves.
Alternatively, because fused silica is a material with low thermal expansion, this resin composition can exhibit excellent properties as an electronic component. Next, the formulations used in the present invention and their proportions will be explained in detail. Spherical silica grains are made by crushing naturally produced silica stone, silica sand, or tridymite and cristopalite obtained by firing these, and then pulverizing them into fine grains using a high-temperature flame using propane, hydrogen, butane, acetylene, etc. as a flammable gas. It can be obtained by passing it inside. The flame temperature is 2000°C or higher, preferably 2200 to 2800°C. The shape of the spherical silica particles is preferably as close to a true sphere as possible, but it may be as long as the rough edges of the particles become smooth due to melting of the surface portion. The crystalline phase of spherical silica is mainly a glass phase, but may also contain quartz, tridymite, and cristopalite in the center.
On the other hand, crushed silica particles are crushed fused silica obtained by crushing fused silica particles and crushed silica stone obtained by crushing silica stone, and are used as they are after being crushed, and the particles are angular. Less than 55% by weight of spherical silica particles or 45% of ground silica particles
If it exceeds % by weight, the fluidity will be poor, the filling property for the resin will be reduced, a resin composition with low expansion property will not be obtained, and the strength will also be reduced. If the amount exceeds 85% by weight of spherical silica particles and is less than 15% by weight of crushed silica particles, the viscosity of the resin will become so low that it will enter the mold gap and cause burrs. If the proportion of these fillers in the resin is less than 50% by weight, the filling effect will not be sufficient and the thermal conductivity and low thermal expansion required for electronic components will not be achieved. When injection molding resin is applied with pressure exceeding 80% by weight, there is a risk that the filler material may cut weak parts of electronic components, such as bonding wires that connect semiconductor elements and leads, or the extraction parts of thin coils. . That is, according to the present invention, it has become possible to mix spherical silica and ground silica without generating burrs and to have a silica filler content of 50% by weight or more. The average particle size of the filler is 5 to 50 μm, and the particle size is
It is 177 μm or less. If the average particle size is less than 5 μm, the specific surface area of the filler becomes large, causing an increase in the viscosity of the compound. An increase in viscosity leads to a decrease in fluidity and deterioration in moldability. If it exceeds 50 μm, fluidity will decrease. When the filler comes into contact with the surface of the IC chip, excessive stress is applied to the silicon, causing malfunction. If the particle size of the filler exceeds 177 μm, the maximum particle size of the filler is regulated to prevent gate clogging when transfer molding the compound.
In recent years, the gate size has become smaller to 177μm.
If this is the case, the gate is likely to be clogged with powder particles, which impedes transfer molding. The type of thermosetting resin is not particularly limited, and for example, epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, etc. can be used. Other additives include curing agents for resins,
Curing accelerators, colorants, flame retardants, mold release agents, coupling agents, etc. can be used as necessary. [Example] Next, examples of the present invention and comparative examples thereof will be shown. Silica stone (crystalline silica) is crushed into fine particles,
Pulverized silica particles with an average particle size of 15 μm were obtained. Spherical silica particles having an average particle diameter of 15 μm were obtained by placing a certain amount of the above-mentioned crushed silica stone into a high-temperature propane-oxygen flame and melting the surface or completely. In each of the following examples, an epoxy resin containing 3% by weight of an amine curing accelerator is used as a paste, and fillers and their proportions are varied. The ICs were sealed using low-pressure transfer molding, and the test results are shown in Table 1. 【table】

Claims (1)

[Claims] 1 Average particle size obtained through high temperature flame: 5~
For burr-free sealing materials containing 50-80% by weight of a filler consisting of 50-μm spherical silica particles and 15-45% by weight of crushed silica particles based on the thermosetting resin composition. Silica-filled resin composition.