JPH0642342Y2 - Cap for semiconductor device encapsulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a semiconductor device sealing cap for sealing a case opening containing a semiconductor chip with a lid.

[Conventional technology]

In a conventional semiconductor device container, a cap is used in which a sealing adhesive is formed to have a uniform thickness on an adhesive surface for adhering to a case accommodating a semiconductor chip. This sealing process is usually
It is performed by applying a uniform pressure to the bonding surface of the case and the cap while performing heat treatment with a series of temperature profiles. The bonding surface between the case and the cap to be bonded is
It is carried out in a process of gradually heating to the melting point of the adhesive under a uniform pressure state, then further increasing the temperature for the purpose of providing fluidity, and then shifting to natural cooling.

[Problems to be solved by the invention]

Examining the state of the adhesive surface in this series of temperature profiles, in the case of a cap with an adhesive layer with a uniform thickness as in the past, when the adhesive started to melt, it was left between the adhesive and the case. Also, even a small gap is filled, and the inside of the container is in a sealed state. Here, when heat treatment at a higher temperature is applied to the sealed container, the pressure in the container rises sharply,
It works to push the adhesive in the flow state toward the outside. In particular, when the semiconductor chip in the container is resin-coated, gas is generated by thermal decomposition of the coating resin, so that the extrusion effect on the adhesive is further enhanced. The effect of pushing the pressure inside the container against the adhesive is to create a thin and weak adhesive part called "pulling down" on a part of the adhesive surface, or to completely penetrate and form a through hole to cause poor airtightness. It lowers the yield and seriously impairs the reliability of the product.

Therefore, a method has been considered in which a groove portion that crosses the adhesive layer is provided to prevent the pressure in the container from rising and to suppress the occurrence of "pulling down" and through holes. Generally, the adhesive does not immediately lose its original shape even when it reaches the melting point and starts to melt. Therefore, in the sealing process according to the normal temperature profile, the container is not sealed at the time when the adhesive starts to melt, because the vent hole due to the groove still remains. When the heat treatment at a higher temperature is applied, the pressure in the container escapes to the outside through the remaining gap, the pressure increase in the container is suppressed, and the extrusion effect on the adhesive is effectively suppressed. Then, the heat treatment proceeds further, the adhesive is fluidized, the groove is closed, and the container is hermetically sealed. In this case, since the airtightness will be poor unless the groove is finally closed with the adhesive, it is necessary to completely close the groove. However, if it plugs too early, it will "pull down" or create a through hole. Therefore, the width of the groove portion, the seal path, and the thickness of the adhesive layer are important in order to obtain the optimum blocking. The wider the groove, the more difficult it is to close the groove. The longer the seal path, the easier it is to close the groove, and the thicker the adhesive layer, the easier the groove is closed. It was necessary to optimize these factors according to the temperature profile of the encapsulation process. If the seal path is long, the groove can be sealed even if the width of the groove varies to some extent. However, if the seal path is not sufficient due to the structure, it is necessary to keep the width of the groove within a narrow range, and sometimes it becomes narrower than the manufacturing tolerance of the groove.
The width of the groove may not suffice for enclosing conditions.
In this case, if the adhesive layer is thickened, the groove will be easily closed. However, since the amount of the adhesive protruding to the outside is large, it often causes a problem in appearance, and it has not been possible to easily increase the thickness of the adhesive layer. Therefore, in the case where the seal path is short, good encapsulation conditions may not be obtained.

[Means for solving problems]

In order to solve the above problems, in the present invention, the adhesive layer provided around the insulating member that covers the opening of the case accommodating the semiconductor chip is provided with a groove that traverses the adhesive layer, and both sides of the groove portion are provided. The adhesive layer in the vicinity is partially thicker than other portions.

When the above-described sealing step is performed using the cap having such a structure, when the adhesive starts to melt, the gas in the container is
Since the adhesive layer still retains its original shape, the inside of the container is connected to the outside air through the groove and is not sealed. Therefore, even if a higher temperature heat treatment is subsequently applied, the pressure in the container does not increase and the extrusion effect on the adhesive is suppressed. further,
Since the adhesive layer near both sides of the groove is thick, it is easy to close the groove.

〔Example〕

FIG. 1 (a) is a plan view showing a first embodiment of the present invention,
FIG. 2B is a sectional view taken along the line AA of FIG. In FIGS. 1 (a) and (b), in the peripheral portion of the insulating member 1,
A sealing adhesive layer 2 is provided, and a groove portion 3 that traverses the adhesive layer is provided at the center of each side of the adhesive layer 2. Further, the thickness of the adhesive layer in the portion 2a on both sides of the groove 3 is thicker than the other portions.

Thus, in the cap having the groove portion 3 in a part thereof, the groove portion 3 remains as a vent hole until the adhesive is in a fluidized state. For example, the melting point of an adhesive for semiconductor device encapsulation obtained by adding a resin material as a binder to glass powder containing lead oxide (PbO) as a main component is 390 to 400 ° C, and the fluidization temperature is 420 to 430.
Although the temperature is ℃, even if it reaches the melting point and begins to melt, the original shape is not destroyed immediately. Therefore, in the sealing process with a normal temperature profile, when the adhesive begins to melt,
Still, the container is not sealed because the vent holes due to the groove remain. When heating is transferred to the second stage and heat treatment at a higher temperature is applied here, the pressure inside the container escapes to the outside from this gap left, so the pressure inside the container does not rise and the extruding effect on the adhesive is The generation is effectively suppressed, and the adhesive layer is surely closed up, and the container is hermetically sealed.

However, if the groove is closed too early, “pulling down” or a through hole occurs. Further, the wider the width of the groove portion, the harder it is to close the groove portion, the longer the seal path, the easier the groove portion is closed, and the thicker the adhesive layer, the easier the groove portion is closed. It is necessary to optimize these factors according to the temperature profile of the encapsulation process. However, when the seal path is short (1 mm or less), the protrusion of the adhesive is limited in appearance, and if the adhesive layer cannot be thickened, appropriate conditions may not be obtained. Therefore, the thickness of the adhesive layer is limited to the vicinity of both sides of the groove, so that the groove can be surely closed and the protrusion of the adhesive can be suppressed to a necessary minimum. Due to the above, even when the seal path is short, the occurrence of "pull-down" or through holes that have occurred in the past in the sealing process is effectively suppressed, and the rate of each occurrence is 1/100.
It can be improved to the following level, and the appearance can be sealed without much difference from the conventional case.

FIG. 2 is a plan view showing a second embodiment of the present invention.
Unlike the first embodiment, in this embodiment, the groove portion 5 is obliquely provided at the center of each side of the adhesive layer 4 around the insulating member 1, and the adhesive layer 4a on both sides of the groove portion 5 is different from the first embodiment. Thicker is the same. Since the groove portion 5 is slanted, the seal path can be apparently lengthened and more optimal conditions can be obtained. As a result, it was possible to effectively suppress the occurrence of "pull-down" or through-holes that occurred in the past in the sealing process.

[Effects of the Invention] According to the present invention, even if the sealing path is short, the occurrence of "pulling down" or through holes in the adhesive layer for semiconductor encapsulation is effectively suppressed, and the rate of occurrence of each is kept to 1/100 or less. Since the container is sealed and the external appearance is not much different from the conventional one, there is a remarkable effect in the encapsulation yield and the improvement of product reliability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a plan view showing a first embodiment of the present invention,
FIG. 2B is a sectional view taken along the line AA of FIG. 2A and seen from the direction of the arrow, and FIG.
It is a top view showing an example of. 1 ... Insulating member, 2,4 ... Adhesive layer, 2a, 4a ... Thick adhesive layer on both sides of the groove, 3,5 ... Adhesive layer transverse groove.

Claims (1)

[Scope of utility model registration request] 1. An insulating member for adhering to a case accommodating a semiconductor chip, the adhesive layer having a transverse groove in a part thereof is formed in the periphery, and the adhesive layer near both sides of the transverse groove is formed. A semiconductor device sealing cap, which is partially thicker than other portions.