JPS6364055B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a semiconductor device having a structure in which electrode terminals of a semiconductor chip are bonded to electrode terminals on a substrate by a CCB method (Controlled Collapse Bonding method) and then coated with a resin. [Background of the Invention] As a specific example to which a semiconductor device having such a structure is applied, as shown in the cross-sectional structural diagram of main parts shown in FIG. A device in which a semiconductor chip for driving a display element is placed and integrally formed is known. That is, the electrode terminal 2 formed on the upper surface of the glass substrate 1
and electrode terminals 4 formed on the lower surface of a semiconductor chip (hereinafter referred to as Si chip) 3 made of a silicon semiconductor are arranged facing each other, and these electrode terminals 2,
Solder bump 5 formed between 4 by CCB method
Then, a flexible resin 6 such as silicon gel is applied to the glass substrate 1 and the Si chip 3.
Furthermore, the top and side surfaces of the Si chip 3 are coated with a bisphenylic low expansion epoxy resin 7 mixed with calcium carbonate. However, for the semiconductor device with the above structure, -
When a temperature cycle test was conducted under the temperature conditions of 40℃←→100℃, the result was that the thermal fatigue resistance was considerably inferior to that of chips without coating (hereinafter referred to as bare chips). As a result of examining the causes of this through experiments and the like, it was found that there are three drawbacks as described below regarding (1) the resin material, (2) the resin coating structure, and (3) the solder bump structure. In other words, when calcium carbonate powder is mixed into epoxy resin, the expansion coefficient can be significantly lowered, but it is still large compared to Si chips or glass substrates.Moreover, increasing the mixing rate of calcium carbonate increases the hardness of the resin. Therefore, thermal fatigue resistance does not necessarily improve. In addition, stress distribution related to the shape of the resin coating using low expansion epoxy resin and the shape of the solder bump, especially stress concentration and flexibility of the solder bump,
Significantly affects thermal fatigue resistance. [Object of the Invention] An object of the present invention is to provide a semiconductor device having a coating resin material, a coating shape, and a solder bump shape that can improve thermal fatigue resistance. [Summary of the Invention] According to the present invention, the coating resin is mainly made of epoxy resin, and a first granular material made of an inorganic material having a coefficient of thermal expansion smaller than that of the epoxy resin, and a first part made of a rubber-like elastic material. The coating resin covers the periphery and the top surface of the semiconductor chip, and the width of the resin coating formed on the top surface of the substrate around the semiconductor chip is such that the width of the resin coating is in the width direction. The solder bumps are designed to have a width of 1 to 1.5 times the width of the semiconductor chip and to form the solder bumps into a cylindrical or cylindrical shape in order to improve thermal fatigue resistance. [Examples of the Invention] The present invention will be described below based on Examples. First, the coating resin material of the present invention will be explained. The coefficient of thermal expansion α _RO of epoxy resin is approximately 100×
10 ^-6 /℃, the thermal expansion coefficient α _Si of a semiconductor chip, such as a Si chip; 3×10 ^-6 /℃, and the thermal expansion coefficient α _G of a substrate, such as a glass substrate, soda glass; 9.33.
It is larger than ×10 ^-6 /℃. Generally, in order to improve thermal fatigue resistance, it is desirable to use a coating resin whose coefficient of thermal expansion is close to that of semiconductor chips and substrates. Therefore, an inorganic material with a small coefficient of thermal expansion (hereinafter referred to as a low-expansion material), such as calcium carbonate or quartz powder, is mixed into the epoxy resin to reduce the expansion. For example, when 50% by volume of quartz powder is mixed, the coefficient of thermal expansion α _R is approximately 25×10 ^-6 /
The temperature drops to ℃. However, as the mixing rate increases, the viscosity of the resin increases and fluidity decreases. When fluidity decreases, it becomes difficult for the resin to penetrate into the voids around the solder bumps during the coating process, resulting in voids remaining, poor adhesion to the board, and reduced coating workability. A problem arises. As a result, thermal fatigue resistance and moisture resistance may be adversely reduced. Furthermore, when the mixing rate is increased, the flexibility of the resin decreases and stress is concentrated at the bonded portion with the substrate, which may damage the substrate such as glass. Therefore, there is a certain limit to the improvement of thermal fatigue resistance simply by mixing a low expansion material to lower the expansion, so it is necessary to further improve the fluidity and flexibility. Therefore, the present invention attempts to improve the flexibility and fluidity by dispersing and mixing particulate elastic material, for example, rubber particles such as polybutadiene or silicone, in addition to the low expansion material. In other words, the rubber particles in the coating resin act as a stress buffer, improving flexibility and alleviating stress concentration and strain, thereby improving thermal fatigue resistance. Further, it is intended to improve fluidity through the action of granular rubber particles. However, as will be described later, there is an optimum range for the mixing ratio of rubber particles. For example, when rubber particles made of polybutadiene (CTBN 1300 x 9) with a particle size of 1 μm are mixed, the weight ratio of the rubber particles to the epoxy resin should be 100:20 or more (hereinafter referred to as parts by weight or simply parts; for example, 20 parts). (expressed as above)
If this is done, the rubber particles will not be uniformly dispersed, and since the coefficient of thermal expansion α _PB of polybutadiene is large at approximately 80×10 ^-6 /℃, the coefficient of thermal expansion α _R of the coating resin after mixing will be large. This causes fatigue and reduces thermal fatigue resistance. Furthermore, even if the fluidity is improved, a significant improvement cannot be expected because of the saturation phenomenon. These matters will be explained based on the results of experiments conducted using Examples. Table 1 shows that the main material is epoxy resin (EP-828), quartz powder with a particle size of about 1 μm is used as a low-expansion material, and uniform rubber particles of polybutadiene with a particle size of about 1 μm are used as a buffer material. The results of the same temperature cycle test as described above are shown below, using semiconductor devices coated with various resins with different ratios as samples. Note that the substrate, semiconductor chip, and solder bumps have the same configuration as shown in Figure 1, and the judgment is that samples that fail in an earlier cycle than those of bare chips without resin coating will be rejected. Those that passed were marked with an "X" mark, and those that passed were marked with a "○" or "△" mark in order of superiority based on the failure rate. As an example of the failure rate, Figure 2A shows the case where the mixing rate of quartz powder is fixed at 35% by volume and the mixing rate of polybutadiene rubber particles is varied.
In Figure 2 B, the mixing rate of polybutadiene rubber particles is 10
The graph shows the cases where the quartz powder is fixed at a certain area and the mixing rate of quartz powder is varied. The solid line in Figures 2A and B is an example of 900 cycles of 1 cycle/1 hour temperature cycle test, and the dotted line in the figure is an example of 500 cycles. It is. The coating resin also contains additives to lower the curing temperature, such as 5% by weight of isodazole (2P4MHz) as a curing accelerator, 10% by weight of dicyanamide as a curing agent, and a silane coupling agent (A-
187) in an amount of 2% by weight, etc., and the curing temperature was set at 130° C. for 1 hour to avoid thermal effects on the substrate.

【table】

〔Effect of the invention〕

As explained above, according to the present invention, in addition to the effects of the resin-coated type which are excellent in shock resistance, vibration resistance, etc., thermal fatigue resistance is improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of a conventional example, and FIGS. 2A and B are diagrams showing the failure rate of an embodiment of the present invention, respectively.
FIG. 3A is a diagram showing an example of the relationship between coating thickness and stress, FIG. 3B and C are explanatory diagrams, and FIG. Figures B and C are explanatory diagrams, Figure 5 is a diagram of the shape of a solder bump, Figure 6 is a diagram showing the relationship between solder bump shape, thermal fatigue life, and mechanical strength; 7A and 7B are stress distribution diagrams of solder bumps, FIG. 8 is a cross-sectional structural diagram of one embodiment of the present invention, FIG. 7B is an explanatory diagram, and FIG. 9 is a cross-sectional structural diagram of another embodiment of the present invention. , FIG. 10 is a block diagram of a device using the CCB bonding method to which the present invention is applied, FIG. 11 is a diagram showing the solder bump temperature for explaining the operation of the embodiment shown in FIG. 10, and FIG. 12 A- C, 13th
14 are structural diagrams of other embodiments of the present invention. 1... Glass substrate, 2... Electrode terminal, 3... Semiconductor chip, 5... Solder bump, 7, 11...
Coating resin, 10...Solder bump, 15...Acrylic resin film, 31...Multilayer printed circuit board.

Claims (1)

[Scope of Claims] 1. A semiconductor chip, a substrate on which the semiconductor chip is mounted, solder bumps formed between opposing electrode terminals of the substrate and the semiconductor chip, and a space around the solder bumps. In the semiconductor device, the resin coating includes a first particulate material made of an inorganic material having a coefficient of thermal expansion smaller than that of the resin, and a second part made of a rubber-like elastic material. 1. A semiconductor device comprising a resin mixed with at least powder or granular material. 2 In the invention described in claim 1,
The resin is an epoxy resin, the first powder is made of at least one of quartz, silicon carbide, silicon nitride, calcium carbonate, and silicon carbide mixed with beryllium oxide;
1. A semiconductor device, wherein the powder is made of at least one of polybutadiene rubber and silicone rubber. 3. In the invention set forth in claim 1 or 2, the mixing rate of the first powder or granular material is 30 to 55.
% by volume, and the mixing rate of the second granular material is 1 to 1.
20 parts by weight of a semiconductor device. 4. In the invention according to any one of claims 1 to 3, the resin coating covers the periphery and upper surface of the semiconductor chip, and the resin coating is formed on the substrate surface around the semiconductor chip. A semiconductor device characterized in that the width is 1 to 1.5 times the width of the semiconductor chip in the width direction. 5. In the invention according to any one of claims 1 to 4, the peripheral region of the resin coating is bonded to the substrate via an acrylic thin layer previously formed on the substrate surface. A semiconductor device characterized by: 6. In the invention according to any one of claims 1 to 5, the substrate is a single substrate made of glass or ceramic material, or made of glass fiber-containing epoxy, glass fiber-containing polyimide, or high-modulus high-strength fiber. A semiconductor device characterized by being an epoxy or polyimide multilayer substrate containing. 7. The semiconductor device according to any one of claims 1 to 6, wherein the solder bump has a cylindrical shape or a cylindrical shape.