JPS63241955A - Manufacture of resin-reinforced lsi mounting structure - Google Patents

Abstract

PURPOSE:To obtain a resin-filled LSI mounting structure having excellent mass productivity by mounting chips on a mounting substrate, then placing resin on the periphery of the chips, evacuating and pressurizing it to fill the resin in the gaps between the chips and the substrate. CONSTITUTION:After silicon chips 1 are flip-chip mounted on a mounting substrate 2, liquid resin 3 is so placed as to cover the periphery of the chips 1, i.e., gaps formed between the chips 1 and the substrate 2. Then, this is filled in a depressurized vessel 9 with a rotary vacuum pump 7, and the resin 3 is evacuated to evacuate from the gaps. Then, the pump 7 is stopped, pressurizing step is started, and the resin 3 is pressed into the gaps. Thereafter, it is returned to a normal pressure stale, and the filling state is checked.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing an LSI mounting structure, and in particular,
The present invention relates to an improved method of manufacturing a mounting structure that is flip-chip mounted and reinforced with resin.

[Conventional technology]

LSI mounting structures, which are formed by mounting an LSI chip on a mounting board via a plurality of electrical junctions, have come to have a large number of junctions as the number of integrated circuits on the chip increases. There is. Therefore, as shown in the fourth page, a flip-chip bonded LSI mounting structure that can form bonding points over the entire LSI chip surface is being considered. in this case,
The connection point is a low contact point alloy so-called solder pillar,
Since these alloys are relatively susceptible to corrosion and oxidation, it is common to take measures to protect them from corrosion and oxidation.

In that case, unless the entire mounting structure is housed and protected in a hermetic package, protection by resin must be relied upon. Protection with resin is very simple and is useful in that this type of mounting structure can be provided at a relatively reasonable price.

However, since the purpose is to prevent corrosion and oxidation, it is not clear whether it is necessary to completely fill the gap between the LSI chip and the mounting board, which are dotted with bonding points, with resin, and in many cases , a situation occurs where complete filling is not possible.

Examples of the methods proposed so far are introduced below, but all of them have many problems in terms of practicality, such as complicated processes or being applicable only to specific devices.

First, a method has been proposed in which a through hole is provided in the surface facing the LSI chip on the mounting board side as shown in FIG. 3, and liquid resin is injected and filled through the through hole. However, highly integrated LSI
In a chip, the junction points are also distributed at high density over the entire surface of the chip, making it substantially difficult to provide desired through holes on the mounting board. Furthermore, since the mounting board also has a group of high-density multilayer wiring, it is very difficult to avoid this and provide through holes. Therefore, this method is applicable only when an LSI chip with few junctions is mounted. However, in the case of glass substrates, etc.

This method is impractical because the through hole becomes a point where glass cracks occur.

Next, in order to avoid the difficulty of filling the gap, as shown in Figure 4, before mounting the LSI chip, liquid resin is placed on the mounting board, and the LSI chip is pressed onto it to bond it. is proposed.

The prerequisite for this method is that the resin does not change significantly at the bonding temperature of the solder used for bonding.

95%pb-5%S commonly used for LSI chip bonding
n or 60%Pb-40%Sn alloy has a maximum temperature of 2
Used at 00-300°C. This temperature is harsh for many uncured resins, and it is difficult to avoid deterioration. Moreover, depending on the resin used, there is a possibility that the self-line function peculiar to flip-chip bonding may be inhibited, and new difficulties will arise in alignment and the like.

On the other hand, as a relatively orthodox method, the fifth
As shown in the figure, after flip-chip bonding, there is a method of filling the chip from the end surface using capillary action.
It was proposed in Publication No. 147140.

Although this method is more practical than the above two methods, it often does not provide satisfactory results depending on the resin. In particular, high viscosity resins containing a large amount of inorganic powder etc. have poor fluidity and often cause filling defects, which limits the range of applicable resins. In addition, there are many factors that depend on the cleanliness of the LSI chip and the mounting board, there is little margin for process conditions, and it takes a considerable amount of time to complete filling, making it difficult to apply to mass production. Furthermore, as the chip size increases, it becomes more difficult to perform void-free filling.

The present invention has been made to overcome these drawbacks of the prior art, and is intended to provide a simpler resin filling method.

[Problem that the invention seeks to solve]

None of the above-mentioned conventional techniques has all the requirements sufficient to be applied as a practical process and has some drawbacks. Among these, the third method of filling using capillary action has the advantages of being able to use conventionally widely used LSI chips and mounting boards as they are, and of being able to follow the conventional mounting structure manufacturing process. Considered the most useful. However, there are problems such as the time it takes to fill, the physical property restrictions regarding the fluidity of the resin, and the fact that it is easily affected by the cleanliness of the LSI chip and the mounting board.

It has the disadvantage of not being suitable for mass production.

The main object of the present invention is to overcome these drawbacks of the prior art and to provide a method for manufacturing a resin-filled LSI mounting structure that is truly suitable for mass production.

Another object of the present invention is to provide a manufacturing process that includes a filling inspection step in which the quality of resin filling can be checked before resin curing.

[Means for solving problems]

The above objects of the present invention are achieved in the following manner.

First, a silicon chip (1) is flip-chip mounted on a mounting substrate (2) in a normal process to obtain a mounting structure (5). Thereafter, a liquid resin (3) exhibiting desired properties after curing is produced as shown in FIG. 1(a).

As shown in (b), the silicon chip (1) is supplied and placed around the silicon chip (1) seamlessly. This step is very important, and the resin
It is important that the periphery of the silicon chip (1) and the periphery of the mounting substrate (2) on which the silicon chip is mounted come into contact with each other to completely close the gap created between the silicon chip and the mounting substrate (2). It is. The resin to be supplied may be degassed in advance.

Next, connect this to the rotary vacuum pump (7) as shown in Figure 1(c).
Place it in a vacuum container (9) with a mark to create a vacuum state. Although a reduced pressure state that can be achieved with a rotary vacuum pump (7) is sufficient,
Specifically, 20 to 10 Torr.

Preferably it is 10 milliTorr or less. In this process,
# Deaeration from fat, silicon chip and mounting board (2)
Air is removed from the gap created by the

In order to facilitate degassing from the gap, the entire mounting structure (5) may be heated by a heating element (8) in order to lower the viscosity of the resin, but the heating conditions at this time are 50 to 50℃. 80℃
is appropriate.

Next, the rotary vacuum pump (7) is stopped and a pressurizing process begins. Air is used as a pressurizing medium.

It is appropriate to use an inert gas such as nitrogen gas, argon gas, or helium gas. Through this process, the resin around the chip is pushed into the gap due to the pressure difference between the gap and the outside, and resin filling is completed.

Although it is possible to heat and harden immediately after that, it is preferable to take a step to check the filling state before that. This is because if the filling is not complete, the process can be stopped and the continued production of defective products can be prevented. Of course, it is not necessary to check the filling state of all mounting structures (5). It is sufficient to check several items for each lot or each time the resin lot changes. Ultrasonic flaw detection is the most effective way to check the filling condition. The mounting structure (5) filled with resin is immersed in water or an inert fluorine-based medium, and ultrasonic flaw detection is performed. Thereafter, the LSI mounting structure is completed by heating and curing using a batch furnace or belt furnace.6 [Function] The LSI mounting structure manufacturing process of the present invention enables void-free resin filling of the LSI chip. The purpose of this method is to perform resin filling while maintaining a reduced pressure state in the gap formed between the mounting board and the mounting board, and to complete the filling while maintaining the reduced pressure state with the resin to be filled. This action ensures resin filling without leaving any voids even when the fluidity of the resin is poor.

For example, filling with resin improves the thermal cycle characteristics of the mounted structure because the coefficient of thermal expansion of the resin is at least as small as the coefficient of thermal expansion of the solder used for bonding. In this case, the inorganic filler is added in an amount that is approximately twice the weight of the resin component, resulting in a fairly viscous resin composition. When attempting to fill such a resin composition using conventional methods,
Not only does it take a considerable amount of time, strict conditions such as temperature control must be set, but even then, complete filling may not be possible.

〔Example〕

Hereinafter, in order to concretely demonstrate the effects of the present invention, an embodiment will be described based on FIG. 1.

[Examples 1 to 12] A silicon chip (1) provided with a solder joint (4) for joining
) is flip-chip mounted onto an alumina mounting board (2) using a normal method. Chip size is 10nw++X
The mounting board (2) has a size of 2Q + nm x 20 mm and a thickness of 1 m. The gap between the chip and the substrate is approximately 100 μm. Solder connection (4)
are distributed over the entire chip surface, and there are 224 of them. to this,
Liquid resin (3) having the composition shown in Table 1 is placed on a mounting structure (5) as shown in FIGS. 1(a) and (b), respectively. Next, these are set in a pressure reducing device (6) constructed as shown in Fig. 1(c), and the pressure is reduced to about 1 milliTorr in the pressure reducing container (9) using a one-rotation vacuum pump (7). . The heating conditions at that time are approximately 60°C.

Heat the hot plate (8) in advance and create an atmosphere of about 60°C before starting the rotary vacuum pump (7). After degassing for 5 to 10 minutes with the 6-rotation vacuum pump (7), Close the valve (10) and gradually open the leak valve (11) to return to normal pressure. Time to return to normal pressure is 1
It takes about 3 minutes.

After completely returning to normal pressure, take out the resin fabric mounting structure (5) from the deaeration tank and remove excess resin around 1, then use ultrasonic flaw detection equipment A T-5000 (manufactured by Hitachi Construction Machinery).
Use to check the filling status. It is immersed in water and measured using a 25 MHz ultrasonic flaw detector.

Thereafter, the resin is cured by heating at 110° C. for 10 hours and then at 200° C. for 10 hours using an air circulation constant temperature bath, thereby completing the resin-reinforced mounting structure (5). Ten pieces of each were made, and the quality of the resin fabrics is shown in Table 1.

[Comparative Examples 1 to 12] Regarding the same composition as used in Examples 1 to 12,
An attempt was made to produce resin cloth using the method disclosed in Japanese Patent No. 0-147140. As a result, the filling good product rate was as shown in Table 2.

As is clear from the comparison between Examples and Comparative Examples, the resin-reinforced LSI mounting structure according to the present invention has a high yield rate for all resin compositions.

This shows that resin cloth tents are made by a mechanism completely different from known methods.

In addition, as a similar method to achieve the object of the present invention.

The mounting structure (5) is placed in a vacuum container (9) in advance, and the liquid resin, which has been filled in a separate cylinder or the like, is maintained in a vacuum state, and after being seamlessly supplied around the chip, the pressure is reduced to normal pressure. It is also possible to take the step of returning it, but the equipment becomes somewhat complicated. In addition, the LSI mounting structure (
As for 5).

As shown in FIG. 7, the method of the present invention is also applicable to a chip having an additional element such as a heat sink (14) on the back surface of the chip.

〔Effect of the invention〕

As described above, according to the resin filling method of the present invention,
A resin-reinforced LSI mounting structure can be obtained with a good yield, and a highly reliable LSI mounting structure can be supplied at a low price.

[Brief explanation of drawings]

FIG. 1 is a diagram for showing the manufacturing method of the present invention, FIG.
) is a plan view of the mounted structure, FIG. 1(b) is an elevational view of the mounted structure, FIG. 1(Q) is a schematic diagram of an apparatus for explaining the depressurization process and the normal pressure process, and FIG. 3, 4, and 5 are all explanatory diagrams showing the conventional resin filling method, and FIG. 6 is a process flow diagram of the manufacturing method of the present invention. FIG. 8 is a sectional view of the mounting structure to which the present invention of FIG. 7 is applied. 1... Silicon chip, 2... Mounting board, 3...
・Resin, 4...Solder connection part, 5...Mounting structure, 6
... Pressure reduction device, 7 ... Rotary vacuum pump, 8 ... Hot plate, 9 ... Pressure reduction container. 10... Valve, 11... Leak valve, 12...
・Nozu No. 1 Fig. 4 Hard

Claims (1)

[Claims] 1. An LSI mounting structure in which an LSI chip on which an integrated circuit is formed and a plurality of bonded bodies related to electrical connection with the mounting board are flip-chip bonded to the mounting board. 1. A method for manufacturing a resin-reinforced LSI mounting structure, characterized in that a gap formed between an LSI chip and a mounting board is filled with resin by a liquid resin filling means that includes the following steps. (1) Step of flip-chip bonding the LSI chip and the mounting board (2) Step of placing liquid resin along the edge of the LSI chip so as to contact the mounting board and the LSI chip all around (3) The mounting structure on which the liquid resin is placed is 10 mm
Step (4) of maintaining the reduced pressure below rr; (4) returning the pressure to normal pressure or above; 2. In an LSI mounting structure in which an LSI chip on which an integrated circuit is formed and a mounting board is flip-chip bonded to a mounting board, on which a plurality of bonded bodies related to electrical connection with the mounting board are formed, the LSI chip and the mounting board are bonded together. A method for manufacturing a resin-reinforced LSI mounting structure, characterized in that a gap formed by a substrate is filled with resin by a liquid resin filling means including the following steps. (1) Step of flip-chip bonding the LSI chip and the mounting board (2) Step of placing liquid resin along the edge of the LSI chip so as to contact the mounting board and the LSI chip all around (3) The mounting structure on which the liquid resin is placed is 10 mm
Step of maintaining the reduced pressure below rr (4) Returning the pressure to normal pressure or above (5) Non-destructively inspecting the filling state of the resin. 3. The resin-reinforced LS according to claim 2, wherein the means for inspecting the filling state of the resin is a flaw detection method using ultrasonic waves.
I. Method for manufacturing a mounting structure.