JPS6314494B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a resin-sealed semiconductor device, and particularly to a method of manufacturing an ultraviolet erasable rewritable read-only storage device (hereinafter referred to as UV-EP-ROM).

UV-EP-ROM is characterized in that the contents (charges) stored in the semiconductor element can be discharged and erased by irradiating the semiconductor element with ultraviolet rays.
Therefore, in such a container, the area above the semiconductor element (active side) must be made of a material that transmits ultraviolet rays.

In order to fulfill the above functions, the conventional UV-EP-ROM container has a main part made of an insulating substrate such as ceramic, and a window made of an ultraviolet-transparent material such as sapphire or transparent alumina above the semiconductor element. Hermetically sealed semiconductor devices have been widely used. This ultraviolet-transparent material is very expensive, and in order to achieve hermetic sealing, it is necessary to match the coefficient of thermal expansion between the materials. Problems often occurred in terms of mechanical impact resistance, etc. Therefore, if we consider the case of trying to obtain a product at a low price by using UV-transparent resin, since UV-transparent resin has a large coefficient of thermal expansion, it is difficult to use it for the entire semiconductor device due to the reliability of the device. This becomes a big problem. In other words, in order to make the UV-EP-ROM a resin-sealed type, it is necessary to use ultraviolet-transparent resin only in the necessary parts, and to use conventional resin in other parts. Therefore, steps other than the encapsulation process in the semiconductor device assembly process can be manufactured using conventional methods, but only the resin encapsulation process requires 2
There is a difficulty in filling only the necessary parts with each type of resin and integrating the resin into one piece. Furthermore, when partial encapsulation is performed, there are problems such as resin flowing out through the bonding fingers of the lead frame and flowing out to unnecessary parts.

The present invention eliminates such drawbacks and provides an improved method of manufacturing a resin-sealed semiconductor device.

The essential feature of the present invention is that when encapsulating UV-EP-ROM with resin, the surface of the semiconductor element is filled with UV-transparent resin, and other resins are added before the resin is completely cured. It is poured into a mold and allowed to harden as a whole.

If such a manufacturing method is adopted, the completed semiconductor device will have a form no different from a conventional semiconductor device, for example, a DIP form, which is convenient for compatibility and handling.

In addition, it is possible to mold two types of resins with different properties, taking into consideration the characteristics of each resin, and it is possible to eliminate the drawbacks of molding them all at once, making it possible to create a more reliable semiconductor device. can.

Hereinafter, the present invention will be explained in detail based on examples. FIG. 1 shows a first embodiment of the invention. An ultraviolet-transparent resin 3 is potted onto a semiconductor element 2 mounted and bonded to a lead frame 1. The potted resin 3 forms a mound as shown in FIG. 1A. It is effective to keep a thin film (not shown) of rubber, resin, etc. in close contact with the back surface of the lead frame to prevent the resin from flowing out from gaps such as bonding fingers of the lead frame. These may be removable after potting, or during subsequent molding.
The resin may remain in the resin of the main body.

When the potted resin is cured, it gradually reacts and hardens, and is set in the mold 5 after being hardened to an extent that its outer shape can be maintained. The situation is shown in FIG. 1B. In this way, the potted head of the UV-transparent resin appears to be slightly crushed by the mold, and it is possible to obtain the maximum surface area with a small amount of UV-transparent resin, as well as Intrusion of resin for molding into the contact area between the mold and the mold can be avoided.

This has the effect that the step of removing the molding resin after molding can be omitted, and a semiconductor device with lower cost can be obtained.

Furthermore, the curing temperature of the UV-transparent resin and the curing temperature of the resin used for molding do not necessarily match, and if they are molded at the same time, the thermal expansion coefficients of both will not match, causing unnecessary stress on bonding wires and semiconductor elements. In addition, as in the present invention, the resin for molding is cured in such a way that it surrounds the ultraviolet-transparent resin, which has a relatively large coefficient of thermal expansion, which causes loose contacts, pellets, cracks, etc. By applying compressive force to the UV-transparent resin, it is possible to control the expansion and contraction of the UV-transparent resin and reduce the effects of tensile force due to heat from the resin for molding, making it more reliable. can be made into a semiconductor device.

Conventional potting technology can be used, and in this respect as well, existing equipment can be effectively utilized. An example of the resin that transmits ultraviolet light used in this example is Shin-Etsu Silicone Co., Ltd.
There are KJR-8030S, KJR-8650S, etc. The distance that ultraviolet rays travel in the resin is 7 mm for the former and 7 mm for the latter.
It is 1.5mm. 180-200nm for KJR-8030S
Output using an ozone ray generating sealed high pressure mercury lamp that emits wavelengths of
5-10 from a distance of 13.5cm using a 1.6kW one
[sec] irradiation, in the case of KJR-8650S, use the above mercury lamp with an output of 2.0 kW and irradiate for 1 to 2 [sec] from a distance of 10 cm to harden to the extent that the initial potted external shape can be maintained.

The complete curing irradiation conditions are 30 [sec] under the above conditions for KJR-8030S, and 6 to 10 [sec] under the above conditions for KJR-8650S.

FIG. 2 shows a second embodiment of the invention. In the second embodiment, unlike the first embodiment, the ultraviolet-transparent resin is cured in a fixed mold rather than in a pot. Even in this case, the resin must not be completely cured. Therefore, it is recommended that the mold 6 used be provided with a coating layer of a material such as Teflon or a rubber lining in order to improve the releasability from the mold as well as a normal mold. . Furthermore, in order to prevent resin leakage from the bonding finger portion of the lead frame, it is also effective to use heat-resistant rubber or rubber lining for the clamping portion 6' of the upper die.

In the first embodiment, the viscosity of the resin must be strictly controlled to avoid potting.
With a mold, there is no need to strictly control the viscosity of the resin; instead, the molding state can be controlled with easily controlled temperatures and times, and the characteristics of the molded UV-transparent resin can be utilized. Can be done. Next, setting the entire resin in the mold 5 for molding in a completely uncured state is the same as in the first embodiment, and the ultraviolet-transparent resin and the mold 5 are The same effect can be achieved by preventing the resin for molding from entering between the layers.

In the first embodiment and the second embodiment, a common effect is that the surface of the semi-cured ultraviolet-transparent resin can be molded into a Fresnel lens shape to improve light absorption.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the present invention;
FIG. 2 is a sectional view showing a second embodiment of the invention. Here, 1... Lead frame, 2... Semiconductor element, 3... Ultraviolet transparent resin, 4... Cavity to be filled with resin for molding the whole, 5... Molding mold, 6
...UV-transparent resin mold, 6'...tightening part,
It is.

Claims (1)

[Claims] 1. A step in which an ultraviolet-transparent resin is provided on at least a semiconductor element, and the ultraviolet-transparent resin is heat-cured to an extent that the outer shape can be maintained without being completely cured, and in this state, the package is placed in a mold that defines the outer shape of the package for molding. 1. A method for manufacturing a resin-sealed semiconductor device, comprising the steps of: filling a resin into the mold and curing the resin.