JPS6224650A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device which has excellent moisture resistance and is hardly influenced by an electron beam by a method wherein moisture-proof resin is applied to the bonding pads formed on the surface of a pellet and electron beam protection material is applied to the surface of the pellet except the bonding pads. CONSTITUTION:A pellet 3 composed of silicon semiconductor is attached to a tab 2 of a lead frame by Au-silicon eutectic method and a film sheet 8 made of polyimide resin is applied to the surface of the pellet 3 with silicon-based adhesive 10. Then bonding pads 7, exposed in the bottoms of the holes 8a in the film sheet 8, are connected to inner leads 5a by bonding wires 4. After that, the holes 8a formed in the film sheet 8 are filled with silicone gel 9 to cover the junction parts of the bonding pads 7 and the bonding wires 4. Then the lead frame is molded by molding material 6 such as epoxy resin which covers the pellet 3 and the wires 4 and outer lead parts 5b, protruding from the package main body are cut and shaped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a technique that is effective when applied to a semiconductor device, particularly a moisture-proofing technique for a sealed pellet and a technique for protecting against electron beams.

[Background Art] In semiconductor devices, particularly in semiconductor devices formed by sealing pellets with synthetic resin such as epoxy resin, moisture easily enters the inside of the package, and as a result, pad portions are susceptible to corrosion.
It is known that disconnection or deterioration of electrical characteristics may occur.

On the other hand, it is also known that electron beams such as alpha rays contained in the synthetic resin that is the sealing material may cause malfunction of the pellet.

The following measures may be taken to address the above two problems.

That is, as a moisture-proofing measure, potting a moisture-proofing material such as silicone gel around the pellets may be considered.

Additionally, as a countermeasure against electron beams, it is possible to cover the beret/upper surface with polyimide resin or the like.

However, even if each of the problems could be solved by the above-mentioned measures, it would not be possible to improve the reliability of the semiconductor device unless both moisture-proofing and electron beam countermeasures were taken in the same semiconductor device. This was discovered by the present inventor.

Regarding this point, it may be possible to first cover the surface of the pellet with polyimide resin as a countermeasure against electron beams, and then to pot silicone gel on the polyimide resin as a moisture-proof measure, but in this method, the potted silicone gel The inventor further clarified that the moisture-proofing effect cannot be exerted sufficiently because the moisture flows from above.

For a detailed example of the technology of resin-sealed semiconductor devices, see Kogyo Kenkyukai Co., Ltd., 1980, 1.
"RLC Mounting Technology" (Japan Microelectronics Association [), published on May 15th, PI37-P139.

[Object of the Invention] An object of the present invention is to provide a semiconductor device that has excellent moisture resistance and is less susceptible to the effects of electron beams.

Another object of the present invention is to provide a semiconductor device with high electrical reliability.

The above and other objects and novel features of the present invention will be apparent from the description herein and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

In other words, by creating a semiconductor device with a structure in which moisture-proofing resin is coated only on the bonding pad portion on the surface of the pellet, and electron beam protection material is coated on the other pellet surfaces, the bonding band, which is easily corroded, can be avoided. The wire joints can be protected from moisture intrusion, and the other pellet surfaces can be protected from electron beams.

Thereby, a semiconductor device with high electrical reliability can be provided.

[Example 1] FIG. 1 is a cross-sectional view showing the entire semiconductor device which is an example of the present invention, FIG. 2 is a partial plan view showing the pellet part,
FIG. 3 is an enlarged partial sectional view of the pellet surface.

The semiconductor device 1 of the first embodiment is a resin-sealed semiconductor device in the shape of a so-called dual in-line package (DIP). Leads 5 as external terminals connected to each other are sealed with a sealing material 6 such as epoxy resin.

As shown in FIGS. 2 and 3, the surface of the pellet 3 of Example 1 is coated with polyimide resin 8 except for the portion of the bonding band 7. Furthermore, a silicone gel 9 is applied to the bonding pad 7 at the connection portion between the pad 7 and the wire 4 .

The method for manufacturing this semiconductor device 1 will be roughly explained as follows.

That is, first, a lead frame (not shown) with the leads 5 and tabs 2 connected thereto is prepared. This lead frame is obtained by processing a metal sheet made of, for example, 4270 mm or Kovar into a predetermined shape by processing such as pressing or etching.

A pellet 3 made of silicon semiconductor is attached onto the tab 2 of this lead frame by the gold-silicon eutectic method.

Next, a film sheet 8 made of polyimide resin having approximately the same size as the surface of the pellet 3 is adhered to the surface of the pellet 3 using a silicone adhesive 10. At this time, as shown in FIG. 2, holes 8a are formed in the film sheet 8 at the portions that contact the bonding pads 7 of the pellets 3. Therefore, when the film sheet 8 is placed on the pellet 3, the portion of the bonding band 7 is exposed to the outside at the bottom of the hole 8a of the film sheet 8.

Next, wire bonding is performed to electrically connect the bonding band 7 exposed at the bottom of the hole 8a of the film sheet 8 and the inner lead 5a.

In this wire bonding, for example, one end of the wire 4 is heated to form a molten ball, and then this ball portion is pressed onto the bonding pad 7 at the bottom of the hole 8a to perform first bonding.

Next, after securing a predetermined length of the wire 4 and forming a loop, the other end of the wire 4 is pressed to a predetermined position of the inner lead 5a under heating conditions while applying ultrasonic vibration to perform second bonding. This is done by doing the following.

After wire bonding is performed in this manner, silicone gel 9 is potted into the hole 8a formed in the film sheet 8, and the bonding portion between the bonding pad 7 and the wire 4 is covered with the silicone gel 9.

At this time, since the silicone gel 9 is potted inside the hole 8a formed in the film sheet 8, the liquid silicone gel 9 does not flow out from the surface of the pellet 3, and moreover, the bonding pad 7 and wire 4, which are easily corroded, are prevented from flowing out from the surface of the pellet 3. Can only be potted at the joint of the

Thereafter, the portion of the lead frame that covers the pellet 3 and wire 4 is molded with a sealing material 6 such as epoxy resin, and the portion of the outer lead 5b that protrudes from the package body (sealing material 6) is cut and molded. The semiconductor device 1 of this example can be obtained.

As described above, according to the first embodiment, the surface of the pellet 3 is covered with the polyimide resin film sheet 8 which has an electron beam shielding effect. Therefore, it is possible to suppress the influence of α rays and the like contained in the components of the sealing material 6, and effectively prevent malfunction of the pellet 3.

Furthermore, a highly moisture-resistant silicone gel 9 is potted at the joint between the bonding pad 7 and the wire 4, which is susceptible to corrosion due to moisture intrusion.

Therefore, an increase in electrical resistance or wire breakage due to corrosion of the wire 4 at the joint portion can be effectively prevented.

[Embodiment 2] FIG. 4 shows a semiconductor device according to another embodiment of the present invention.
) is an enlarged partial sectional view showing the portion.

The semiconductor device of Example 2 is substantially the same as the semiconductor device described in Example 1, but the structure of the pellet surface is different.

That is, in Example 2, the polyimide resin layer 28 is directly adhered to the surface of the pellet 3 without using an adhesive or the like.

That is, in Example 2, the polyimide resin layer 28 was formed at the stage of wafer processing before the pellets 3 were divided. The polyimide resin layer 28 is formed by, for example, applying a resist material to the wafer surface and performing an etching process to remove a predetermined portion of the resist material to form a pattern of a predetermined shape on the wafer. Next, by depositing the polyimide resin layer 28 and removing the resist material, the polyimide resin N28 can be formed only on the portions of each pellet 3 excluding the bonding pad portions 7.

In this way, after forming the polyimide resin jliF2B in advance at the wafer processing stage, the wafer is divided into pellets 3, and then the same steps as in Example 1 are performed, thereby producing the semiconductor described in Example 1. Similar to device 1, it is possible to provide a semiconductor device that prevents malfunctions and has high moisture resistance.

In Example 2, as described above, the polyimide resin N2B can be formed on a plurality of pellets 3 at once in the wafer processing process, so that the polyimide resin N2B can be efficiently deposited. can.

[Effects] (1) By creating a semiconductor device with a structure in which moisture-proofing resin is coated only on the bonding pad portion on the surface of the pellet, and electron beam protection material is coated on the other pellet surfaces, the bonding pad Corrosion can be prevented at the joints between the pellets and the wires, and the other pellet surfaces can be protected from electron beams.

(2) By covering the pellet surface with a polyimide resin having holes formed in the portion that contacts the bonding pad portion, it is possible to prevent the silicone gel from flowing out when the silicone gel is potted.

(3) According to (1) and (2) above, it is possible to provide a semiconductor device with excellent moisture resistance and electron beam shielding, thereby improving the reliability of the semiconductor device.

(4) By performing the deposition of polyimide resin during the wafer processing process, efficient deposition work can be performed.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, in Example 1, a case was described in which a film sheet made of polyimide resin was applied to each pellet, but this is not limited to this.It is also possible to apply a film sheet at the wafer stage and then divide it into individual pellets. good.

In addition, although the method for joining the pellet to the tab has been described only using the gold-silicon eutectic method, the method is not limited thereto, and joining may be performed using a brazing material such as silver paste.

Further, in the embodiments, polyimide resin is used as the electron beam shielding material, and silicone gel is used as the moisture-resistant resin.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a sectional view showing the entire semiconductor device of Example 1 of the present invention, FIG. 2 is a partial plan view showing the pellet portion of the semiconductor device of Example 1, and FIG. 3 is an enlarged partial sectional view of the pellet portion of the semiconductor device of Example 1, and FIG. 4 is an enlarged partial sectional view of the pellet portion of the semiconductor device of Example 2. DESCRIPTION OF SYMBOLS 1...Semiconductor device, 2...Tab, 3...Pellet, 4...Wire, 5...Lead, 5a...Inner lead, 5b...Outer lead, 6...Sealing Stopping material (epoxy resin), 7... Wire, 8... Film sheet (polyimide Hf resin), 8 a... Hole, 9...
... Silicone gel, 10 ... Adhesive, 28 ... Polyimide resin layer. Figure 2

Claims (1)

[Claims] 1. A moisture-proofing resin is applied only to the bonding pad portion on the surface of the sealed pellet, and an electron beam protection material is applied to the other surfaces of the pellet. Semiconductor equipment. 2. The electron beam protection material is a sheet-shaped polyimide resin,
2. The semiconductor device according to claim 1, wherein a silicone gel as a moisture-proofing resin is potted into a hole formed at a position in contact with the bonding pad of the polyimide resin. 3. The semiconductor device according to claim 1, wherein the sealing is made of synthetic resin.