JPH04111386A - Electronic device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic device having a semiconductor device, and in particular,
Thin IC package (TSOP: Th1n Small
The present invention relates to a technique that is effective when applied to a memory module equipped with a large number of semiconductor devices of 0 utlina package or a thin memory equipped with a TSOP.

[Conventional technology]

Conventional semiconductor integrated circuit (IC) boards have an SOJ (Small*utline J-1ead) mounted on the mounting package.
edP ackage), S OP (S wall
0utline Package), the package height from the board surface is 2n or more, and the lead height is 1mm or more.
I am using C package.

The technology related to the IC package board is described in "Nikkei Electronics J, September 7, 1987 issue, p.99-1.
It is described in 07.

[Problem to be solved by the invention]

However, as a result of studying the above-mentioned prior art, the inventor found the following problems.

The above conventional technology does not take into account the concept of matching the thermal expansion coefficients of the TC package and the board when mounting a thin IC package with a thickness of about one inch on the board, and the solder joints of the leads are soldered. Strain due to the difference in expansion coefficients is added, causing cracks or breaks, and the reliability of solder joints has become a problem.

The purpose of the present invention is to ensure the reliability of the soldering part in modules equipped with a large number of ICs by applying specifications that match the coefficient of thermal expansion of the board as much as possible to the value of the IC package. Our goal is to provide the technology that is possible.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of one typical invention disclosed in this application is as follows.

A single layer or multilayer board of 10 or less layers with a thermal expansion coefficient of 7.0 x 10-" to 3.OXI○'"1 is used, the spacing between opposing lead terminals is 10 mmz or more, and the lead from the board is This is an electronic device in which at least one semiconductor device of a package with a height of 0.7 mm or less is mounted.

The multilayer wiring board has a multilayer wiring structure in which copper foil is pasted on both sides of a ceramic core board, prepreg made by impregnating glass cloth with epoxy resin and dried is laminated, and copper foil is pasted on top of that. The above-mentioned surface mounting is performed by soldering.

[For production]

According to the above-described means, when the TSOP is soldered and mounted on the module board, the leads at both ends of the molded portion of the TSOP are soldered to the board, respectively. Therefore, the base of the lead undergoes a displacement proportional to the coefficient of thermal expansion of the TSOP in response to temperature changes, but the tip of the lead soldered to the substrate side undergoes a change proportional to the coefficient of thermal expansion of the substrate.

Therefore, if the difference in thermal expansion coefficient between TSOP and substrate is large,
The difference in displacement between the lead base and the lead tip becomes large, and this strain is applied to the soldering part of the lead tip.

Therefore, by matching the thermal expansion coefficients of the TSOP and the substrate, it is possible to minimize strain on the solder joints due to temperature changes.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be specifically described using the drawings.

In all the figures for explaining the embodiments, parts having the same functions are given the same reference numerals, and repeated explanations thereof will be omitted.

FIG. 1 is a cross-sectional view for explaining the schematic configuration of an embodiment in which the present invention is applied to an electronic device in which a TSOP type semiconductor device is mounted on a ceramic core substrate.

2 is a cross-sectional view showing the structure of the ceramic core substrate shown in FIG. 1, and FIG. 3 is an enlarged view of the surface mounting section shown in FIG. 1.

In the electronic device of this embodiment, as shown in FIG. 1, leads 3 of a TSOP type semiconductor device 2 are bonded (soldered) onto a ceramic substrate 1 with solder 4.

It has been implemented. The thickness of the package of the TSOP type semiconductor device 2 is approximately 1.27 mm.6 As shown in FIG. , on top of that, a glass cloth was impregnated with epoxy resin and dried.
Prepreg ICs with a thickness of 0 μm are layered, a copper foil IB with a thickness of approximately 18 μm is pasted on top of the prepreg ICs, and a copper foil IB with a thickness of approximately 100 μm is placed on top of it.
■It has a multilayer wiring structure in which thick prepreg ICs are laminated and copper foil IB with a thickness of about 18 μm is pasted on top of it.

TSOP (package) body 2 of the semiconductor device 2
The longer the distance between A and C, the longer the distance between TSOP and board 1.
Distortion due to the difference in thermal expansion coefficients increases.

When the force due to the aforementioned strain is applied to the solder joint, as shown in FIG. Since the strength of solder 4 is low, breakage may occur at the solder 4 portion. Therefore, in the present invention, as shown in FIG. 2, a ceramic core material is adopted as the material of the ceramic core substrate 1, and the ceramic core substrate l
The difference in coefficient of thermal expansion between the TSOP body 2A and the TSOP body 2A is reduced, and the reliability of the solder joint is increased.

The type of TSOP, lead rigidity, and soldering will vary depending on the situation, etc., but if we take a glass epoxy board (thermal expansion coefficient 15 x 10-'/''C) for comparison, the difference in thermal expansion coefficient with Tsop is: This is approximately 7.6X10'-', which is four times the difference (1,9X104) in the case of ceramic substrate 1. Therefore, by using ceramic core substrate 1, the life of the solder joint is approximately 10 times longer. It is estimated that it will grow to a certain extent.

In this way, according to this embodiment, the ceramic core substrate 1
Since it is possible to reduce the difference in the coefficient of thermal expansion between the TSOP and the mounted TSOP (thin package), the strain applied to the solder joints during temperature changes can be reduced, and the reliability of the solder joints can be improved.

In addition, in a temperature cycle test after soldering the TSOP semiconductor device 2, the solder peeling failure rate was
As shown in Table 1, after 1000 cycles, 7 out of 14 glass epoxy substrates became defective. On the other hand, in ceramic core substrate 1, there were 0 defects out of 18 defects.

On the other hand, in ceramic core substrate 1, the number of cycles is 1.
There were 0 defects out of 18 in 5oO cycles.

As can be seen from the experimental results, according to this example,
It is possible to reduce the strain applied to the solder joint when the temperature changes, and improve the reliability of the solder joint.

Table 1 FIG. 4 shows a modification of this embodiment.

In this modification, a groove 6 for mounting an electronic component 7 such as a chip capacitor is provided on the ceramic core substrate 1 side. With this configuration, the ceramic substrate 1 is easily deformed in the groove 6, so the force applied to the solder joint is reduced, and the reliability of the solder joint is improved.

The present invention has been specifically explained above based on examples, but
The present invention is not limited to the embodiments described above, and does not depart from the gist thereof! It goes without saying that various changes can be made in the surroundings.

〔Effect of the invention〕

To briefly explain the effects obtained by the representative inventions disclosed in this application, the difference in thermal expansion coefficient between the board and the mounted thin package can be reduced, so that solder joints can be bonded even when the temperature changes. The strain applied to the solder joint can be reduced, and the reliability of the soldered joint can be improved.

[Brief explanation of drawings]

Figure 1 shows a TS of the present invention on a ceramic substrate. A cross-sectional view for explaining the schematic configuration of an embodiment applied to an electronic device mounted with a P-type semiconductor device, FIG. 2 is a cross-sectional view showing the configuration of the ceramic core substrate of FIG. 1, and FIG. FIG. 1 is an enlarged view of the surface mounting section, and FIG. 4 is a diagram showing a modification of this embodiment. In the figure, 1...ceramic substrate, 2...semiconductor device. 2A... TSOP body of semiconductor device, 3... Lead, 4... Solder, 5... Footprint wiring, 6
...Groove, 7...Electronic parts.

Claims (3)

[Claims] 1. Thermal expansion coefficient is 7.0×10^-^6~3.0×10
＾-＾Using a 6-layer single-layer or 10-layer or less multilayer wiring board,
An electronic device, characterized in that at least one semiconductor device is mounted in a package in which the distance between opposing lead terminals is 10 mm or more and the height of the leads from the multilayer wiring board is 0.7 mm or less. 2. The multilayer wiring board has a multilayer wiring structure in which copper foil is pasted on both sides of a ceramic core board, prepreg made by impregnating glass cloth with epoxy resin and dried is laminated, and copper foil is pasted on top of that. The electronic device according to claim 1, characterized in that the electronic device has the following characteristics. 3. 3. The electronic device according to claim 1, wherein the surface mounting is performed by soldering.