JPS59204259A - Method for sealing semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate the cause for the generation of disconnection by a method wherein a protection coat using a gelled thixotropic Si composition is provided only at the memory part except for the parts of the electrode and connection of the surface of a semiconductor element. CONSTITUTION:Said Si composition is used as a coating material 1, Which is applied only to the memory part 2, except for the electrode 3 and the connection 4. In this case, said Si composition means a composition generating an elastic gel by polymerization. Thereby, the generation of disconnection is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for encapsulating a semiconductor device, and more particularly to a common type of coating that shields a semiconductor element from alpha rays from nature.

It is well known that when α planes generated in nature enter a part of the memory of a semiconductor device, the device malfunctions. Therefore, in order to protect the semiconductor element from the influence of this alpha ray, a coating made of a resin material such as silicone or polyimide is applied to the semiconductor element, and then the semiconductor element is sealed with a curable resin composition. was.

As shown in FIG. 1 (cross section), the coating 1 covers not only the memory part 2 of the semiconductor element 5 but also the acid electrode part 3 and the connection 4 between the electrode and the lead frame 6. It was a good thing that it was done normally due to work reasons.

Such protection 1. When applying φ coating, silicone elastic gel, which has a particularly low elastic modulus among nuclide materials, exerts strong stress on the covered part, and even if it comes into contact with moisture, it may cause corrosion of the electrode or current leak. It is considered to be advantageous because it rarely occurs, and is used quite often.

However, even when the silicone gel-coated element experiences a sudden change in ambient temperature, wire breakage occurs at a defective part of the wire connection.

The purpose of the present invention is to eliminate the cause of such IJIL failure. It is recommended that the wire breakage is caused by stress acting on the portion a of the wire connection surrounded by the dotted line in FIG. 1 because the wire connection strength and the coefficient of thermal expansion of the silicone gel are different. Therefore, the invention includes the use of a coating material that limits the application area of the coating and is provided with workability that makes this possible, as well as semiconductor devices to which this method is applied. That is, the feature is that in a semiconductor device encapsulation method in which a 4υ is formed on the surface of a semiconductor element and then sealed using a resin composition, a gelatinable thixotropic silicone composition is used as the material to be encapsulated. This can be achieved by applying the protection to only a portion of the memory, excluding the electrodes and connection portions on the surface of the semiconductor element.

In the present invention, as shown in FIG. 2, the stub 1 is applied only to a portion 2 of the memory, and the electrodes 3 and connections 4 are excluded. Therefore, a portion such as a in FIG. 1, which may cause wire breakage, cannot be formed. The thickness of the oak is at least 40 mm.
~50 μm is desirable.

With commonly available gelatinous silicone compositions, if applied to only a portion of the memory to this thickness, it is difficult to cast along the element surface and adhere to one pole or connection part. By using a composition having a silica bond, it is possible to avoid adhesion to them and to cover only a portion of the memory.

The term "gelling silicone composition" as used herein means a composition that produces an elastic gel by polymerization, and is usually formed by the action of a polymerization initiator or catalyst to form a terminal solvent and side chain functional groups of a silicone prepolymer molecule. There are many types that form a sigelloid through an addition reaction with a crosslinking agent (polyfunctional monomer). As mentioned above, the composite is required to have thixotropic properties, and this property requires a particle size of 1 μIn or less, especially several tens of μIn.
It is applied by a known method such as blending 0.001 to 1% by weight of 7 Lika fine powder.

Next, examples of the present invention will be described.

Fine silica powder (average particle size: about 5011 nl), which is a sicuntropic agent, is added to the south component of a commercially available gelling two-component silicone (viscosity at 25C of 50 to 70 poise) in an amount of 0.000 m2 based on the weight of the resin component. IM electrolyte was mixed. In this mixture,
Crosslinking agent/catalyst component (viscosity 20-25 voids at 25C)
After mixing, the mixture was dropped onto the ice surface of a portion of the memory of a 64xbit memory device, and applied in the form of a hill with a thickness of about 50 μm. After that, 100tJC1:18J1 then T150C
The coating was completely gelled by treatment for 1 hour.

No adhesion of the gel was observed on the electrodes or wire connections. Next, this coated element was sealed using an epoxy resin composition by a transfer molding method. Although 100 sealing elements were subjected to temperature cycles of -1961r to +150C 2000 times, no wire breakage occurred. on the other hand,
Using a silicone composition without adding Norica fine powder, M
In the same test, the element coated to a thickness of approximately 5 Q 71 III and sealed with resin in the same manner as above in the state shown in Figure 1 was 1
8 out of 00 wire breaks occurred.

[Brief explanation of drawings]

Figure A1 and Figure 2 are cross-sectional views showing the portion of the semiconductor element covered by the safety iron. l...Coating gel, 2...Memory, 3...'44
M, 4... Wire connection, 5... Semiconductor element, 6... Lead frame, 7... Substrate. Agent: Patent Attorney Akio Takahashi (Figure 1, Figure 2)

Claims (1)

[Claims] 1. In a semiconductor device sealing method in which a protective nuclide is formed on the surface of a semiconductor element and then sealed using a resin composition,
Sealing of a semiconductor device, characterized in that a gelatinable cyclotropic silicone composition is used as a material to be coated, and the eye-keeping coating is formed on a part of the memory except for the electrodes and connection parts on the surface of the semiconductor element. Method.