JPH06271837A - Epoxy-sealing agent - Google Patents

Abstract

PURPOSE:To obtain an epoxy.sealing agent capable of efficiently carrying out fixation of a circuit element temporarily fitted to a case and air-tight sealing of the case by blending a liquid epoxy main agent and a particulate curing agent with a filler having larger diameter than that of the curing agent. CONSTITUTION:(A) A liquid epoxy main agent and (B) a particulate curing agent are mixed with (C) a filler having larger diameter than that of the component B to give the objective sealing agent, which is permeated from a hole bored through an under cover of the case, fixes a circuit element 3 temporarily to the case and hermetically seals the case. To be concrete, for example, a condensate between Bisphenol A and epichlorohydrin is used as the component A, diaminodiphenylmethane having 4-20mum particle diameter as the component B and ground silica having 100mum particle diameter as the component C to prepare the sealing agent. A crushed silica is preferable as the component C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an epoxy sealant for fixing circuit elements and hermetically sealing them.

Epoxy resin is inexpensive and has heat resistance, chemical resistance,
It is used as an electrical insulating material and paint because of its excellent electrical and mechanical properties, but is also widely used as an adhesive.

A hermetically sealed package was initially used as an exterior of circuit parts such as semiconductor parts including capacitors and inductances. However, due to the progress of the passivation technology for circuit elements and the improvement of encapsulating resin, it is used in almost all fields. As a result, resin-sealed packages have come to be used.

There are various kinds of encapsulating resins, which are used depending on the application and the operating environment.
An epoxy resin having excellent heat resistance is used for sealing a circuit element which itself generates heat, such as an LSI or an LSI.

Further, as a method of forming a resin package, a method of casting a resin by a transfer molding method and sealing it, and a method of housing a circuit element in a resin case and covering the circuit element and then adhesively sealing the resin with a resin are used. There is.

The present invention relates to an epoxy sealant used for the latter adhesive sealing.

[0007]

2. Description of the Related Art Epoxy adhesives used as a sealant are classified into two-part type and one-part type.

Although there are many kinds of epoxy resins, a typical one is a resin composed of a condensation product of bisphenol A and epichlorohydrin, to which a curing agent such as an aliphatic amine or phthalic anhydride is added. By doing so, a crosslinking reaction is caused, and the resin is cured.

Here, the two-part adhesive is a liquid-type condensation resin having an epoxy ring and a liquid-type curing agent, which are separately stored and mixed when used. A crosslinking reaction occurs.

On the other hand, the one-component adhesive agent uses, as a curing agent, imidazole which is crystalline at room temperature, an aromatic amine which is in a solid state, or a phenolic curing agent which is in a solid state. It is a mixture with the above-mentioned condensation resin, and since the curing agent is solid, the crosslinking reaction does not proceed at room temperature, but the curing agent is dissolved by heating, whereby the crosslinking reaction proceeds and cures.

Here, the two-liquid type is generally used as an adhesive, but the one-liquid type is often used in the manufacturing process of electronic parts because it is easy to use. The present invention relates to a sealant using this one-component adhesive, and the present invention will be described below by taking a small relay as an example.

FIG. 2A is a plan view of the back cover of the small relay,
FIG. 1B is a perspective view from the back side showing a position where sealing is performed using an adhesive, and FIG. 1C is a perspective view showing a state where a sealing agent is injected.

That is, a small relay is inserted and temporarily fixed in the resin case 1, and the input / output terminals of the small relay are circuit-connected to eight lead terminals 2. A small gap is provided between the terminal 2 and the bottom plate.

Here, in order to improve the reliability of the small relay, it is necessary to adhesively fix the yoke portion of the temporarily fixed small relay to the resin case, and the lead terminal 2
It is necessary to fill the gap between the bottom plate and the bottom plate with resin to ensure moisture resistance.

Therefore, as shown in FIGS. 2 (A) and 2 (B), a recess 3 into which a sealing agent is poured is provided on the back surface of the resin case 1.
And an inflow hole 4 are provided. The inflow hole 4 is for allowing the sealant to flow into the resin case 1 and reach the yoke of the small relay, and the yoke is bonded and fixed to the resin case 1.

Here, the sealing treatment with the epoxy sealing agent is performed by supplying the sealing agent to the concave portion 3 of the resin case 1 and filling it, and then performing a heat treatment at 100 ° C. for about 1 hour.

FIG. 2 (C) shows a state in which the sealant 5 is supplied to the recess 3, and the enlarged view shows the relationship between the epoxy main agent 6 constituting the sealant 5 and the hardener 7 which is uniformly dispersed. And the hardening agent 7 is formed by the subsequent heat treatment.
Melts and reacts with the epoxy main agent 6, causing cross-linking polymerization to be cured as an epoxy resin.

However, since the viscosity of the sealing agent is lowered in this heat treatment step, the amount of the sealing agent flowing into the resin case 1 is larger than that of the inflow hole 4, and in some cases, the inflow hole 4 is opened.
In some cases, airtight sealing could not be achieved, and improvement was necessary.

[0019]

As a resin outer packaging method for electronic parts, a circuit element is inserted and temporarily fixed in a resin case having lead terminals, and a sealant is applied from the outside of the resin case having an inflow hole 4. There is a method of supplying a part of the resin into the resin case to fix the electronic component to the resin case and filling a gap between the lead terminal and the resin case to hermetically seal.

However, there is a case where the sealing agent which flows in from the inflow hole 4 excessively enters in the heat curing treatment and the inflow hole 4 opens to cause a sealing failure, and this improvement is necessary.

[0021]

[Means for Solving the Problems] The above-mentioned problems are permeated through an inflow hole provided in a lower lid of a resin case to fix an electronic component temporarily fixed in the resin case and to hermetically seal the resin case. Epoxy sealant characterized in that the one-pack type sealant used for stopping is formed by adding a liquid epoxy main agent and a particulate curing agent with a filler having a larger particle size than this curing agent. Can be solved by using.

[0022]

In the present invention, by adding a filler having a large particle size to the sealant, the flow resistance when the epoxy main agent and the granular curing agent flow into the resin case by heating is increased, which results in excess sealant. It is to prevent the inflow.

That is, the heating for causing the crosslinking reaction is 10
It is carried out at 0 to 110 ° C. for a long time of about 1 hour, during which time the curing agent gradually softens and melts into a liquid to react with the epoxy main agent to proceed with crosslinking.

Here, the viscosity of the epoxy main agent and the curing agent decreases as the temperature rises and permeates into the resin case due to gravity, so that an excessive inflow of the sealant composed of the mixture of the epoxy main agent and the curing agent is eliminated. Therefore, it is necessary to prevent the viscosity from decreasing. In the present invention, a filler is added in advance, and the viscosity is prevented from decreasing due to the frictional force between the filler and the epoxy main agent and the granular curing agent.

Here, as the filler to be added, a crushed filler is more effective than a spherical filler, and it is necessary that the filler has a larger particle size than the curing agent in order to increase the frictional force. .

FIG. 1 shows the back of a small relay which is sealed by using a sealant embodying the present invention, and corresponds to FIG. 2 (C) which is a conventional method. That is, as shown in the enlarged view of FIG. 2C, the conventional sealant 5 is composed of the epoxy main agent 6 and the curing agent 7, while the sealant according to the present invention is shown in the enlarged view of FIG. As shown in the figure, in addition to the epoxy main agent 6 and the curing agent 7, a flow resistance is increased by dispersing a filler 8 having a particle size larger than that of the curing agent 7.

It should be noted that the filler 8 must not be sized so as to hinder the intrusion of the sealant into the inflow hole. As described above, the present invention suppresses the decrease in viscosity of the epoxy resin due to heating by adding the filler to the conventional sealing agent, and thus the excessive inflow of the sealing agent can be eliminated.

[0028]

EXAMPLE A condensate of bisphenol A and epichlorohydrin was used as the epoxy resin constituting the one-pack type epoxy sealant, and an aromatic amine was used as the curing agent, and the particle size was 4 Approximately 20 μm of ciaminodiphenylmethane is used, on which average particle size of 100 μm crushed silica
10% by weight of (SiO ₂ ) was added to form a sealant.

Next, the small relay shown in FIG. 1 was used as a target object for epoxy sealing. Here, the dimensions of the resin case are 15 × 10 × 10 mm (length × width × height), while the inflow holes are 300 × 500 μm and four are provided as shown in the figure. The yoke of a small relay, which is temporarily fixed to the back cover provided with the inflow hole, is in contact therewith.

The depth of the concave portion into which the sealant is injected is 1
mm. Epoxy sealing is performed by supplying the above sealing agent to the recess of the resin case using an injector to fill the recess, and then placing it in a constant temperature bath maintained at 110 ° C for 1 hour. Heated to cure the resin.

Then, the surface condition of this resin encapsulant was observed, but no sinking as in the conventional case was observed. On the other hand, the small relay was firmly fixed to the back surface of the resin case. It was possible to eliminate the imperfections.

[0032]

The use of the epoxy sealant according to the present invention makes it possible to fix electronic components and hermetically seal them in good yield.

[Brief description of drawings]

FIG. 1 is a perspective view of a back cover of a small relay sealed with a sealant according to the present invention.

FIG. 2 is a plan view (A) and perspective views (B) and (C) of a back cover of a small relay showing sealing with an epoxy sealant.

[Explanation of symbols]

 1 Resin Case 2 Lead Terminal 3 Recess 4 Inflow Hole 5 Sealant 6 Epoxy Main Agent 7 Curing Agent 8 Filler

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H01L 23/28 L 8617-4M 23/29 23/31

Claims (1)

[Claims] 1. A one-component sealant used for permeating through a hole provided in a lower lid of a case to fix a circuit element temporarily fixed in the case and to hermetically seal the case. The epoxy sealant is characterized in that a liquid epoxy main agent and a particulate curing agent are added with a filler having a larger particle size than the curing agent.