JPH0637228A - Semiconductor device - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To improve the mountability by making it possible to control the amount of solder at the tip of the lead of a semiconductor device. A tip 4 of a lead 3 from a semiconductor device in a resin portion 2 is soldered to a conductor wiring 5 on a substrate 1.
In this case, the In-based solder 4a and Pb / S are previously attached to the tip portion 4.
An n-based solder 4b is provided, and the solders 4a and 4b are sequentially melted and joined by heating from a low temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved semiconductor device suitable for mounting on a semiconductor package having leads with a narrow pitch.

[0002]

2. Description of the Related Art A QFP with a lead pitch of 0.3 mm has been developed in line with the miniaturization, thinning, and increased pin count of LSI packages
(Quucl Flat Package) has emerged. In this case, the biggest problem lies in a method of improving a defect due to a solder bridge, lead floating, etc., which accompanies a narrow lead pitch. The method currently being studied is to improve the method of printing cream solder on a printed circuit board (for example, optimizing the shape of the solder powder and improving the accuracy of the screen mask), which causes the solder bridge that causes solder bridges. It controls the variation of the quantity.

[0003]

However, it can be said that either method is insufficient for control. Another problem is that the lead width is becoming narrower as the pitch becomes narrower, and it is necessary to prevent lead bending. At present, the lead is often bent after the lead plating in the solder plating process.

An object of the present invention is to provide a semiconductor device capable of improving a problem at the time of mounting by improving a solder portion of a lead.

[0005]

In order to achieve the above object, a semiconductor device of the present invention is provided with a tip region to which a first type solder having a predetermined melting point temperature is applied by a predetermined method, and adjacent to the tip region. The gist of the present invention is that it has a lead formed of a region formed by applying a second type solder having a melting point temperature higher than the predetermined melting point temperature by the predetermined method. In this case, the predetermined method may be a clad method, and the first type of solder is a solder selected from the group consisting of In-based and Bi-based, and the second type of solder. May be Pb / Sn based solder. Furthermore, more specifically, the tip region in which solder selected from the group consisting of In-based and Bi-based is applied by the cladding method, and the tip region in which Pb / Sn-based solder is applied by the cladding method. It is also possible to use a lead consisting of a region adjacent to.

[0006]

In the semiconductor device of the present invention described above, the amount of solder can be controlled, and a plurality of solders having different compositions are changed, so that the mountability is excellent.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In general, the wiring part on the PC board and the LSI package are joined by a solder plating layer attached to the leads of the LSI package and a cream solder printed on the PC board or a solder layer pre-coated on the wiring part on the PC board. Joining is performed. Further, in order to prevent the displacement of the LSI package, a fixing adhesive is also applied between the package body and the PC board before soldering.

According to the present invention, a solder strip plate is press-contacted only to the tip portions of the leads by, for example, the clad method during the processing of the lead frame material. Since the thickness can be controlled with high accuracy, the amount of solder can be controlled compared to other methods. It is also possible to limit it to only necessary parts. The lead frame processing of the material is performed by a known method. The present invention takes advantage of these advantages and is characterized in that different compositions of solder are attached to specific portions.

FIG. 1 is a sectional view of an embodiment of the present invention. In the figure, the tip 4 of the lead 3 derived from the semiconductor device built in the resin portion 2 connected to the PC board 1 is connected to the conductor wiring with two kinds of solder compositions as shown in FIG. First, the flat portion of the tip portion 4 is made of In-based or Bi-based low melting point solder 4a, and the bent portion is made of Pb / Sn system 4b. In the temperature profile of reflow soldering, the temperature is gradually raised from a low temperature to avoid problems due to rapid heating (such as the tombstone phenomenon).

Therefore, in the present invention, first, the amount of solder that the low melting point solder on the flat portion 4a of the lead 3 melts and joins in a low temperature range is controlled, and there is no extra protrusion such as cream solder. There is no misalignment. Next, the temperature is gently raised, and P of the bent portion 4b is increased in the high temperature range.
The b / Sn solder melts and joins. As shown in FIG. 3, since the fillet shape of the bent portion of the joint of the lead 3 influences the strength, a Pb / Sn-based solder having high strength is used. By using solders having different characteristics according to the manufacturing conditions and the lead structure, high-performance connection is possible. The solder used in the present invention and the coating method thereof are not limited to the solder composition and the clad method shown in the above embodiments.

[0011]

As described above, according to the present invention, the mountability of a semiconductor device having a multi-pin and narrow-pitch lead on a substrate is remarkably improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a tip of a lead obtained by a solder clad method in the above embodiment.

FIG. 3 is a cross-sectional view of a lead after lead bonding in the above embodiment.

[Explanation of symbols]

 1 substrate 2 resin part 3 lead 4 lead tip part 4a low melting point solder 4b high melting point solder

Claims (4)

[Claims] 1. A tip region coated with a predetermined type of solder having a predetermined melting point temperature by a predetermined method, and a second region provided adjacent to the tip region and having a melting point temperature higher than the predetermined melting point temperature. A semiconductor device having a lead consisting of a region to which a type of solder is applied by the predetermined method. 2. The semiconductor device according to claim 1, wherein the predetermined method is a clad method. 3. The first type of solder is In-based and B-based.
The semiconductor device according to claim 1, wherein the solder is selected from the group consisting of i-based solder, and the second type of solder is Pb / Sn-based solder. 4. A tip region to which a solder selected from the group consisting of In-based and Bi-based is applied by a cladding method, and a tip region to which Pb / Sn-based solder is applied by a cladding method are adjacent to each other. A semiconductor device having a lead composed of a region having