JPS59186352A - Semiconductor resin sealing method - Google Patents

Abstract

PURPOSE:To realize highly reliable resin sealing by providing a single or plural independent bubble-containing body to the semiconductor element attached on the lead frame and the vicinity thereof. CONSTITUTION:The required part including a semiconducltor element 2, a die pad 3 and a lead frame having the lead belt 1 is sealed by an independent bubble containing body made of inorganic material or organnic material. As the inorganic material, silica, glass, alumina or calcium silicate are used while as the organic material, a heat hardening or thermosetting resin is used, such materials are sealed by the hard independent bubble containing body 6 and moreover it is covered with a low viscosity resin 5 which assures the low pressure molding. In such a sealing method with such structure, resin sealing assuring moisture proof characteristic, alpha-ray shielding characteristic, excellent productivity and a low hardening stress can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor resin sealing method for sealing required parts including a semiconductor element, a die pad portion, and a lead frame having an IJ-doped strip with a sealing resin. More specifically, in order to produce semiconductor resin-encapsulated products with excellent moisture resistance, alpha ray shielding properties, and productivity, and low curing stress, semiconductors that contain single or multiple closed cells are added to the semiconductor element. Regarding resin sealing method.

2. Description of the Related Art Conventionally, in order to protect semiconductor components such as ICs from the external environment, an outer layer has been formed on all or part of semiconductor components. The mainstream of formation of the outer layer was hermetic sealing using metal or ceramic, but resin sealing using sealing resin has been replaced in production volumes.

As the resin sealing method, a transfer molding method is used in which a sealing resin that has been heated and softened in advance or a liquid sealing press is press-fitted into a mold.

The sealing resin used is a mixture of epoxy resin, silicone resin, etc. with a curing agent, filler, flame retardant, coupling agent, coloring agent, etc. Epoxy resin type sealing resin is especially used. Most commonly used.

The inside of the semiconductor encapsulation product manufactured by the transfer molding method using the epoxy resin thread encapsulation resin is completely filled with the encapsulation resin, for example, Process C (hereinafter, Process C will be described as a representative example of semiconductor parts). ) chips and bonding wires are in direct contact with the encapsulating resin.
It is characterized by excellent moisture resistance, vibration resistance, thermal conductivity, and impact resistance.

Shikashi In recent years, as the degree of integration of IOs has improved, there has been a demand for sealing materials with even higher reliability in terms of the above-mentioned characteristics, and problems such as 77 error due to alpha rays generated from the sealing materials have been raised. In particular, chip destruction or soft errors due to curing stress can be improved by conventional methods, such as resin purity, filler purity and mixing amount, catalyst type and mixing amount, surface treatment agent type and amount used, and sealing. Even after investigating various sealing methods, the problem cannot be solved, and the highly integrated process C has the disadvantage that it cannot be sealed with resin. In particular, when the encapsulating resin has a high viscosity, drawbacks such as sagging of gold wires in ICs and the like are highlighted.

It has been found that the occurrence of defects in the moisture resistance test of resin-sealed mold C is due to moisture permeating through two systems: the sealing resin layer and the bonding interface between the resin layer and the resin layer. The water that permeates through them dissolves impurities in the sealing resin, and the water itself changes to alkaline or acidic, and it is thought that this water reaches the aluminum electrodes on the chip surface and corrodes the aluminum electrodes. There is.

In order to solve the above corrosion problem, efforts have been made to improve the purity of resins and fillers, the type and amount of catalysts mixed, the type of coupling agents and treatment methods, and improvements have been made year by year. However, there are limits to the improvement of characteristics by such methods, and it is difficult to completely solve the above problems.

Resin-sealed C-chip failures due to cracks or distortion are caused by the curing stress of the sealing resin. In order to solve such problems, a filler such as silica is mixed into the resin in order to minimize the difference in linear expansion coefficient between the engineered C chip and the sealing resin. Fillers currently used in sealing resins include silica, glass, ceramics, etc., and antimony trioxide, which is a flame retardant. (similar). However, even if a large amount of filler is mixed, it is fundamentally difficult to eliminate the difference in linear expansion coefficient between the sealing resin and the IC chip. There is a problem in that radiation emitted from thorium or uranium, etc., which is present, reaches the surface of the IC chip, and the energy thereof causes a soft error in which the IC malfunctions. To prevent this, the surface of the IC chip is coated with a resin such as imide resin, which has a low uranium content and hardly emits alpha rays, but this has not been effective enough.

Disadvantages include poor workability of Shikamo coating and high material costs. As mentioned above, a resin containing an inorganic filler or the like cannot be applied to high-integration construction C.

On the other hand, a hollow cage such as a hermetic ring has good characteristics, but is expensive, and is prone to troubles due to external vibrations and shocks, which are often the cause of defects in construction C.

As mentioned above, resin encapsulation of engineering C chips, which will become increasingly highly integrated, will face problems such as moisture resistance, chip cracking due to hardening 1+]+ force of the encapsulation resin, and soft errors due to gold wire sagging or alpha rays. ing.

The inventors of the present invention have made extensive research in view of the above-mentioned problems, and as a result, have developed a semiconductor resin sealing method in which a desired portion including a semiconductor element, a Guibat portion, and a lead frame having a lead strip is sealed with a sealing resin. In the method, 42. It has been found that the above-mentioned drawbacks can be overcome by providing a body containing - or a plurality of closed cells.

That is, in the present invention, by disposing single or multiple closed cell containing bodies on and around the semiconductor element,
If the curing stress of the sealing resin (due to IC chip cracking and distortion, soft errors caused by alpha rays, and gold wire sag) can be reduced, and moisture resistance can be improved, a significant increase in l/X can be achieved.

Closed-cell containing materials formed according to the present invention, inorganic and/or organic materials, low-boiling inert media, gas-generating and decomposing substances, reaction gas-generating substances, water, solvents, It can be obtained by applying gas and/or heat. Since the air bubbles contained in the closed cell containing body are small, the sealing resin force does not penetrate into the air bubbles (it is preferable that the air bubbles do not have any influence on the air bubbles). A highly pure and hard foam-containing material is preferable because it has good moisture resistance and is free from soft errors and deformation due to sealing.

Inorganic materials used in the present invention include glass, alumina, and calcium silicate; organic materials include urethane resin, silicone resin, polyester resin, phenolic resin, melamine resin, epoxy resin, and polyethylene. Examples include thermosetting resins and thermoplastic resins such as resins, polystyrene resins, polypropylene resins, polyamide resins, polyimide resins, polyphenylene sulfide resins, and polyether ether ketone resins.

The closed cell-containing body formed by the present invention only needs to be large enough to accommodate the chip C and the bonding wire, and there is no particular restriction on its proportion in the resin encapsulation C.
It is desirable that the content be 40% by volume or less so as not to impair the mechanical strength of the glass.

The sealing resin used in the present invention includes general-purpose thermosetting resins such as epoxy resins, urethane resins, polyester resins, silicone resins, general-purpose thermoplastic resins, etc.
For example, polyphenylene sulfide resin, polyamide resin, etc. have hardening agents, fillers, flame retardants, coupling agents, etc.
Examples include sealing resins mixed with colorants, etc., preferably low-viscosity epoxy resins that do not deform closed cell-containing bodies, urethane resins, polyester resins/silicone resins, and polyphenylene sulfide.
The method of the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of resin encapsulation C manufactured by a conventional method, showing the bonding of an IC chip (2) attached to a lead frame (1), a die nozzle (3), and a gold wire. A conventional resin sealing process a is shown in which a wire (4) is sealed with a sealing resin (5) by a method such as a transfer molding method. In the resin sealing process C using the conventional method, the process C chip (2) and the gold wire bonding wire (4
) is directly sealed in the sealing resin (5), so it is directly exposed to the curing stress of the sealing resin (5) and alpha rays caused by the filler.

FIG. 2 is a schematic cross-sectional view of the resin encapsulation C manufactured by the method of the present invention, in which the encapsulation C chip (2), die pad (3) and gold wire bonding wires are attached to the lead frame (1). (4) A closed cell containing body (6) is formed using urethane resin, silicone resin, polystyrene resin, phenol resin, etc. on and around it, and the body is sealed with sealing resin (5) by a method such as transfer molding. The resin sealing process C according to the method of the present invention is shown. Resin sealing process C according to the method of the present invention is a process in which the C chip (2) and the gold wire bonding wire (4) are formed into a closed cell containing material (6).
Since it is fixed and protected by the sealing resin (5) and does not come into direct contact with the sealing resin (5), it is not directly affected by the curing stress of the sealing resin (5) or the alpha rays emitted from the filler in the sealing resin (5). , those of the closed cell containing body (6). Therefore, the disadvantages of the conventional method can be overcome by using a closed cell containing body (6) which has a small hardening force and does not contain a filler. Also, in terms of moisture resistance, there is no inferiority compared to those made by conventional methods.

Next, the method of the present invention will be explained based on Examples and Comparative Examples.

Examples 1 to 12 A C chip shown in Table 1 was bonded to a lead frame, and after wire bonding, CFC was mixed with a urethane resin to form a closed cell containing body shown in Table 1 on the IC chip and bonding wire. , ■ made 'w+bore 500
Resin sealing was carried out using No. 0, and a resin sealing process C similar to the resin sealing process C shown in FIG. 2 was obtained. The resulting resin sealing ■C had no defects due to gold wire sagging.

Moisture resistance, heat cycle resistance, heat shock resistance, and moisture resistance and high mass resistance were measured for the obtained resin sealing process C1, and the results are shown in Table 1.

The measurement was carried out by placing 100 samples under the following conditions and performing a function test to determine the percentage of defective products. ) Moisture resistance = 120°a, 2 atm, humidity 100%, 5000
Time heat cycle knee 55°C x 60 minutes and 125
°C! Shearability: -190°OXS minutes and 2600 cycles
0x5 minutes for 50 cycles Humidity resistance: 1200 as 2 atm, humidity 100%
DC in the state of! Applying 10V for 1000 hours Also, IC chips c51521 and c532 in Table 1
06 and 05G1400 are bipolar carving Oa5t521.05. manufactured by Mitsubishi Electric. ! +206 and MO3 engineering 005G 1400.

Example 13 A porous layer was formed in the same manner as in Example 1 using a 64 kilobit dynamic chip manufactured by Mitsubishi Electric ■ whose surface was not coated with an organic material instead of the engineering a chip used in Example 1. Resin sealing was performed to obtain resin sealing process C similar to resin sealing process a shown in FIG.

Resin encapsulant C obtained! 100 pieces were each set in a measuring device, measured for 1000 hours, and the soft error rate that occurred was determined.

The results are shown in Table 2.

Comparative Examples 1 to 3 Resin sealing similar to resin sealing XC shown in FIG. 1 was performed in the same manner as in Example 1 except that the closed cell containing body produced in Example 1 was not produced using the materials shown in Table 1. Stop C was produced.

Using the obtained resin sealant C, moisture resistance, heat cycle resistance, heat shock resistance, moisture resistance, and bimass resistance were measured in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Example 4 A resin-sealed Xa was produced in the same manner as in Example 13 except that the closed cell containing body produced in Example 16 was not produced, and the soft error rate was determined.

The results are shown in Table 2.

From the results shown in Table 2 and Table 1, the IC sealed by the method of the present invention has better moisture resistance, heat cycle resistance, heat shock resistance, and moisture reverse bimass resistance than the IC sealed by the conventional method. It can be seen that it has excellent properties.

Regarding moisture resistance, the direct contact area between the closed cell containing body and the engineered C chip is reduced, which improves moisture resistance.
Regarding heat shock resistance, it is thought that the stress caused by the sealing resin applied to the C-chip is reduced by the presence of the closed cell containing material. There is also a remarkable difference in moisture resistance and reverse bimass properties, indicating that unless the sealing resin is applied directly to the C-chip, the aluminum electrodes on the surface of the C-chip are less likely to corrode.

Also, from the results in Table 2, the I sealed by the method of the present invention
It can be seen that C is of good quality with no soft errors occurring at all. This result is also expected because the closed cell containing material has the effect of shielding alpha rays generated from thorium, uranium, etc., which are present as impurities in the inorganic filler contained in the sealing resin.

As detailed above, by forming a single cell or multiple closed cell containing bodies around the engineering C chip, moisture resistance, chip cracking due to curing stress, leisure folding (gold wire breakage), and soft errors due to alpha rays are achieved. Problems related to engineering C parts such as these are solved at the same time. The +jit method can be employed as a sealing method not only for engineering C components but also for all semiconductor devices.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of resin sealing ■c by the conventional method.
FIG. 2 is a schematic cross-sectional view of resin sealing C according to the method of the present invention. (Drawing codes) (1): Lead frame (2): Engineering C chip (3), Guibat (4): Bonding wire (5): Sealing resin (6): Closed cell containing agent Masu Oiwa 141 ( (2 people)

Claims (1)

[Scope of Claims] (1) In a semiconductor resin encapsulation method in which a desired portion including a semiconductor element, a die pad portion, and a lead frame having a lead strip is encapsulated with a sealing resin, a single layer is placed on and around the semiconductor element. A semiconductor resin encapsulation method characterized by forming one or more closed cell containing bodies. (2) The single or plural closed cell containing bodies are made of an inorganic material and/or an organic material.
Sealing method described in section 1). (8) The sealing method according to claim (2), wherein the inorganic material is silica, glass, alumina, or calcium silicate. (4) The sealing method according to claim (2), wherein the organic material is a thermosetting resin or a thermoplastic resin. (5) The sealing method according to claim (1), wherein the single or plural closed cell containing bodies are hard. (6) The pressure sealing method according to claim (1), wherein the sealing resin is a sealing resin using a low-viscosity resin that can be molded at low pressure.