JPS6241440Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a package structure of an EPROM (a read-only memory device in which stored information can be written and erased).

(b) Prior art and problems EPROM is usually formed from semiconductor elements and is known as a semiconductor memory device, but this
It is a type of semiconductor device called IC or LSI. Semiconductor packages (containers) that enclose devices such as ICs and LSIs can be roughly divided into ceramic type and synthetic resin (plastic) type. Ceramic type is expensive, but it is suitable for ICs that require high reliability. Plastic molds are used for general products because they can be made at low cost. however,
As technology advances, their reliability as IC elements has also increased, and it has become possible to obtain sufficiently high reliability even when they are encapsulated in plastic without the need for strict sealing. Therefore, the number of plastic packages has been increasing steadily recently.

Ceramic packages have traditionally been used for EPROM packages, and although they are highly reliable, they are expensive. Therefore, like other logic circuit elements, RAM (random access memory), ROM, etc., a plastic package is desired, but all the plastic materials currently in use are black or dark brown and have light-shielding properties. It is difficult to erase semiconductor devices by irradiating them with ultraviolet light from the outside, so EPROMs are inevitably limited to ceramic packages.

Figure 1 shows the product sealed in a ceramic type package.
This shows an external view of the EPROM. 1 is a ceramic substrate (alumina material), 2 is a lead terminal, and 3 is a transparent glass window surrounded by a metal plate.
The memory is erased by irradiating it with strong ultraviolet light. However, ceramic type packages are expensive as mentioned above, and even if other ICs and LSIs are encapsulated in plastic molds to reduce costs, EPROMs cannot be made cheaper.

Furthermore, ceramic type packages have the disadvantage that memory loss (soft errors) may occur due to trace amounts of radiation from radioactive elements contained in the ceramic, and the effects of external noise (electromagnetic waves) cannot be prevented.

(c) Purpose of the invention The invention aims to solve these problems,
The purpose is to reduce the cost of EPROM and simultaneously achieve the effect of preventing soft errors from occurring and shielding against external noise (electromagnetic waves).

(d) Structure of the invention The object of the invention is to make the outer surface of the EPROM element molded from transparent plastic, excluding the transparent window necessary for erasing the memory information of the internally sealed EPROM element,
This is achieved by a package having a structure coated with a conductive and light-blocking coating.

(e) Example of implementation of the idea A detailed description will be given below with reference to the drawings.

Conventionally, there are two types of plastic materials used to encapsulate transistors, ICs, and LSIs: thermosetting resins and thermoplastic resins, and transparent plastics are often thermoplastic, but the present invention is not limited to these. In short, it is made of transparent plastic that is heated to high temperatures and then injected into a mold to solidify.

After that, only the transparent window portion is masked and conductive coating is applied. Figure 2 is an external view of the EPROM package according to the present invention formed in this way.
1 is a painted transparent plastic, 13 is a transparent window, and 12 is a lead terminal.

As a method for applying conductive coating, there is, for example, a method of vapor depositing an aluminum film. In this case, it is necessary to mask the surrounding area of the lead terminal 2 during vapor deposition to avoid a short circuit with the lead terminal 2. on the other hand,
Coating the outer surface with such a conductive paint has the advantage of shielding it and eliminating the influence of external noise (electromagnetic waves) on the internal EPROM.

In addition, plastic encapsulation can reduce soft errors as described above, and prevent the influence of external noise (electromagnetic waves) as described above, thereby improving reliability.

On the other hand, plastic sealing does not require the use of expensive ceramic packages, and it is possible to inject and shape many pieces at the same time using a mold.
The number of man-hours required is extremely reduced, and the combined cost of materials and man-hours can be reduced by several hundred yen.

(f) Effects of the invention Therefore, according to the invention, EPROM can be obtained at a very low cost, and the effects of soft errors and external noise (electromagnetic waves) can be reduced. is very large.

[Brief explanation of drawings]

FIG. 1 shows a conventional EPROM package, and FIG. 2 shows an EPROM package according to the present invention. In the figure, 1 is a ceramic substrate, 2 and 12 are lead terminals, 3 is a glass window, and 13 is a transparent window.

Claims (1)

[Scope of utility model registration request] An EPROM that is molded from a transparent synthetic resin and whose outer surface, except for a transparent window necessary for erasing memory information of the EPROM element sealed inside, is coated with a conductive and light-shielding coating. Packaging.