JPH04313260A - Surface-mounted device using resin for preventing crack - Google Patents

Abstract

PURPOSE:To prevent crack, etc., from being produced at a resin by achieving a force which is strong against thermal stress or internal stress by applying a specific resin to a resin mold of IC. CONSTITUTION:A special glass fiber reinforced unsaturated polyester resin with an improved heat resistance is applied to a resin mold 1a of IC. When a mold portion is allowed to flow at a soldering bath with water contents absorbed, the resin has heat resistance even if thermal stress or internal stress is generated, thus achieving a strength which is strong against those forces and hence preventing crack, etc., from being produced at the resin.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a general-purpose surface mount device, and more particularly to a crack-proof IC resin mold.

0002

2. Description of the Related Art A conventional IC resin mold will be explained with reference to the drawings.

FIG. 4 is a cross-sectional view of a conventional surface-mounted device when the resin molded portion absorbs water.

In FIG. 4, the conventional surface mount device is composed of a conventional resin mold 1b, lead pins 2, a chip 3, and a chip/lead frame 4. is based on epoxy resin.

Therefore, in the conventional resin mold 1b, when the mold portion absorbs moisture, the moisture diffuses into the resin. When the IC is fixed to a printed circuit board, it passes through a solder bath, where heat stress is applied and the water in the resin evaporates and vaporizes.

At this time, a large stress is generated inside, and since the epoxy resin of the conventional resin mold 1b does not have very good heat resistance, if the bending strength of the resin is exceeded, cracks as shown in Fig. 4 occur. do.

[0007]

[Problems to be Solved by the Invention] As mentioned above, in conventional IC resin molds, when heat is applied, the resin does not have excellent heat resistance, so if the bending strength of the resin is exceeded, cracks occur and the IC It has the disadvantage of causing deterioration.

The purpose of the present invention is to solve the above-mentioned drawbacks by applying a special type of glass fiber reinforced unsaturated polyester resin to the resin mold of IC, and to prevent thermal stress even if it is poured into a soldering bath while absorbing moisture. It is an object of the present invention to provide a surface mount device using a crack-preventing resin that is strong enough to withstand internal stress and is less likely to cause cracks in the resin.

[0009]

[Means for Solving the Problems] A surface-mounted device using the crack-preventing resin of the present invention uses glass fiber-reinforced unsaturated polyester resin as the mold material of the resin mold of the surface-mounted device.

0010

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of a surface mount device according to an embodiment of the present invention, FIG. 2 is a side view of the surface mount device of FIG.
FIG. 3 is a cross-sectional view of the resin molded portion of the surface mount device of this example when it absorbs water, FIG. FIG. 3 is a diagram showing a place where stress and internal stress are generated.

In FIGS. 1, 2, and 3, the surface mount device of this embodiment includes a resin mold 1a and lead pins 2.
, a chip 3, and a chip lead frame 4.

[0013] Here, a special type of glass fiber reinforced unsaturated polyester resin with excellent heat resistance is used for the resin mold 1a of this IC.

[0014] When the mold part absorbs moisture and is poured into the soldering bath as shown in Fig. 3(a), the mold part absorbs moisture as shown in Fig. 3(b).
Even if thermal stress or internal stress occurs, the resin is heat resistant and has the strength to withstand such forces.

[0015]

[Effects of the Invention] As explained above, the surface mount device using the crack prevention resin of the present invention can absorb moisture by applying a special glass fiber reinforced unsaturated polyester resin to the IC resin mold. When poured directly into a soldering bath, it can withstand thermal stress and internal stress, and has the effect of being less likely to cause cracks in the resin.

[Brief explanation of drawings]

FIG. 1 is a front view of a surface mount device according to an embodiment of the present invention.

FIG. 2 is a side view of the surface mount device of FIG. 1.

FIG. 3 is a cross-sectional view when the resin molded portion of the surface-mounted device of this example absorbs water. FIG. 3(a) is a diagram showing how the resin mold part absorbs moisture. Figure 3 (
b) is a diagram showing a place where thermal stress and internal stress are generated due to moisture.

FIG. 4 is a cross-sectional view when a resin molded portion of a conventional surface-mounted device absorbs water.

[Explanation of symbols]

1a Resin mold 1b Conventional resin mold 2 Lead pin 3 Chip 4 Chip lead frame

Claims (1)

[Claims] 1. A surface mount device using a crack-preventing resin, characterized in that a glass fiber-reinforced unsaturated polyester resin is used as a mold material for a resin mold of the surface mount device.