JPH06334090A - Lead structure of resin sealed semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To shape the tip of a lead so that a solder fillet can be formed easily by making a solder plated notch at the tip of the lead on the mounting surface side. CONSTITUTION:Prior to machining the lead of a lead frame, a groove 11a is made at a part of a lead frame material 11 becoming the tip of lead on the mounting face side. Solder plating 4 is then conducted on the surface and rear of the lead material 11 and in the groove 11a. The lead frame is then cut along a cut line 5 by means of a cutter 6 thus making a notch 10a. Thereafter, the lead 10 is shaped and mounted on the footprint pattern 8 of a printed board 7 before it is soldered. Since the notch 10a at the tip of the lead 10 is subjected to solder plating 4, a good solder fillet 9 can be formed. Furthermore, visual inspection can be effected accurately and easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead structure for a resin-sealed semiconductor device capable of forming a good solder fillet when mounted on a substrate and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the development of electronic devices has been remarkable.
Along with this, semiconductor device packages have been diversified. In particular, the trend toward lighter, thinner, shorter, and smaller electronic devices has increased, increasing the need for high-density board mounting.From the board-inserted packages up to that point, surface mount packages that can be mounted on both sides of the board have become available. It is the mainstream.

FIG. 6 is a view showing a lead structure of a conventional resin-encapsulated semiconductor device. Particularly, FIG. 6 (A) is a side view thereof,
FIG. 6B is a plan view thereof. As an example, a QFP (Quad Flat), which is one of surface mount packages
Package). In the figure, 1 is a package resin portion such as epoxy, 2 is a lead, and the lead 2 is processed into a shape called "culwing".

FIG. 7 is a plan view of the lead frame in which the package is resin-sealed. In this example,
About 5 packages are connected to one lead frame. Then, as shown in FIG. 8, solder plating 4 is applied to the front, back, and side surfaces of the lead frame material 3.
Has been applied. The thickness of the solder plating 4 is usually at least about 5 μm. Then, after cutting the lead frame on the cut line 5 (shown by a chain line) by the cutting blade 6 (shown by a dotted line), the lead frame is processed into a lead shape shown in FIG. Incidentally, as the lead processing method, the same shape can be obtained even when the lead bending is performed simultaneously or after the lead bending is performed. At this time, the lead frame material 3 is exposed on the cut surface 2a at the tip of the lead 2,
Solder plating 4 is not attached. Then, the resin-sealed semiconductor device processed into the shape called "gull wing" is shipped to the user.

On the other hand, as shown in FIG. 10, the user mounts the leads 2 of the resin-encapsulated semiconductor device on the footprint pattern 8 (printed with solder paste or the like in advance) of the printed circuit board 7. . Then, when soldering is performed by a reflow method or the like, a solder fillet 9 is formed and the resin-sealed semiconductor device can be fixed onto the printed circuit board 7. At this time, since the solder plating 4 is not applied to the cut surface 2a at the tip of the lead 2, the solder fillet 9 has the cut surface 2a.
There is almost no climb up to.

[0006]

However, in the lead structure of the resin-encapsulated semiconductor device having the above structure, particularly when the lead frame material 3 is a copper-based alloy, the temperature applied during the assembly process and during soldering mounting As a result, the cut surface 2a at the tip of the lead 2 is oxidized. Therefore, as shown in FIG. 10, the solder fillet 9 is less likely to be formed on the cut surface 2a. Further, when the lead frame material 3 is an iron-based alloy, the cut surface 2a at the tip of the lead 2 is difficult to oxidize, but when the distance (pitch) between the leads is narrowed, a short circuit between the leads occurs. In order to prevent this, the supply amount of the solder paste is suppressed, so that the solder fillet 9 is not easily formed on the cut surface 2a at the tip of the lead 2. As described above, since the solder fillet 9 is less likely to be formed, (A) reliability is deteriorated due to insufficient strength of the connection surface after soldering, and (B) whether or not it is a good product at the time of visual soldering inspection. Is difficult to judge. Particularly, in the visual soldering inspection, generally, the degree of formation of the solder fillet 9 is visually recognized and confirmed. However, on the package side of the solder fillet 9, the contact state between the leads 2 and the solder fillet 9 is Since it cannot be seen from above, it cannot be visually inspected.

[0007] As described above, with the use of copper-based alloys and the narrowing of pitches, the cut surface of the lead is
There is a problem that solder plating cannot be applied, and solder fillets are less likely to be formed during solder mounting.

The present invention eliminates the problem that solder plating cannot be applied to the cut surface of the lead and the solder fillet is less likely to be formed at the time of soldering mounting. An object of the present invention is to provide an excellent structure processed into a shape in which a solder fillet is easily formed and a manufacturing method thereof.

[0009]

In the lead structure of a resin-sealed semiconductor device according to the present invention, a solder-plated notch is provided on the board mounting surface side of the tip of the lead.

A method of manufacturing a lead of a resin-encapsulated semiconductor device according to the present invention comprises: a lead frame material before lead processing;
A first step of forming a groove, a second step of forming solder plating on the front, back, and side surfaces of the lead frame material on which the groove is formed, and cutting with a groove of the solder-plated lead frame, And a third step of processing into a lead shape.

[0011]

According to the present invention, a good solder fillet can be formed when a resin-sealed semiconductor device is mounted on a substrate.

[0012]

1 is a view showing an embodiment of a lead structure of a resin-sealed semiconductor device according to the present invention, and in particular, FIG.
1A is a side view thereof, and FIG. 1B is a plan view thereof.
As an example, QFP, which is one of surface mount packages
(Quad Flat Package) is shown. In the figure, 10 is a lead, and this lead 10 is processed into a shape called "culwing". Further, a notch 10a is formed on the substrate mounting surface side of the tip of the lead 10 by a process such as half etching.

FIG. 2 is a plan view of the lead frame with the package sealed with resin. In this case, about 5 packages are connected to one lead frame, but the lead frame material 11 is shown as it is before the solder plating.

Next, a manufacturing process of the lead structure of the resin-sealed semiconductor device shown in FIG. 1 will be described. First, as shown in FIG. 2, in the lead frame in which the package is resin-sealed, before the lead processing of this lead frame, as shown in FIG.
Of the lead, and on the board mounting surface side,
The groove 11 is previously processed by a process such as half etching.
a is formed. At this time, it is desirable that the width W and the depth D of the groove 11a have a relationship of D ≦ T / 2 with respect to the plate thickness T in order to secure the strength of the lead 10. And
As shown in FIG. 3B, the solder plating 4 can be formed in the groove 11 a by applying the solder plating 4 to the front, back, and side surfaces of the lead frame material 11. Then, the lead frame is cut by the cutting blade 6 (shown by a dotted line) into a cut line 5 (shown by a one-dot chain line).
When cut above, as shown in FIG. 3 (C), the notch 1
You can make 0a. Then, the lead 10 is processed into the lead shape shown in FIG. As the order of processing the leads, it is possible to make the notches in the same manner by cutting the leads and bending them at the same time, or by cutting the leads after bending.
By this manufacturing process, the notch 10a can be formed on the board mounting surface side of the tip of the lead 10, and the solder plating 4 can be applied to the notch 10a. Then, the package processed into the shape called "gull wing" is shipped to the user.

On the other hand, as shown in FIG. 5, the user mounts the leads 10 on the footprint pattern 8 (preprinted with solder paste etc.) of the printed circuit board 7 and then solders them by a reflow method or the like. When the attachment is performed, the solder fillet 9 is formed, and the resin-sealed semiconductor device can be fixed.

At this time, the notch 10 at the tip of the lead 10
Since the solder plating 4 is applied to a, a good solder fillet 9 can be formed. Moreover,
The visual solder inspection can be performed accurately and easily.

[0017]

As described above in detail, according to the lead structure of the resin-encapsulated semiconductor device and the method of manufacturing the same according to the present invention, a solder-plated notch is formed on the substrate mounting surface side of the lead tip. As a result, a good solder fillet is formed at the time of board mounting, and sufficient bonding strength is obtained.
Moreover, there is an effect that the visual lead inspection after soldering can be accurately and easily performed.

[Brief description of drawings]

FIG. 1 is a side view and a plan view showing an embodiment of a lead structure of a resin-sealed semiconductor device according to the present invention.

FIG. 2 is a plan view showing a lead frame before the solder plating process of FIG.

FIG. 3 is a cross-sectional view showing the manufacturing process of FIG.

4 is a detailed cross-sectional view showing the lead of FIG.

FIG. 5 is a cross-sectional view showing leads of a mounted semiconductor device.

FIG. 6 is a side view and a plan view showing a conventional device.

FIG. 7 is a plan view showing the lead frame of FIG.

FIG. 8 is a cross-sectional view showing the lead frame of FIG.

9 is a cross-sectional view showing the lead of FIG.

FIG. 10 is a cross-sectional view showing a lead of a mounted conventional semiconductor device.

[Explanation of symbols]

 9 Solder fillet 10 Lead 10a Notch 11 Lead frame material 11a Groove

Claims (2)

[Claims] 1. A lead structure of a resin-encapsulated semiconductor device, comprising: a lead structure of a resin-encapsulated semiconductor device, wherein a solder-plated notch is provided on a substrate mounting surface side of a tip of the lead. 2. A method of manufacturing a lead of a resin-encapsulated semiconductor device, comprising: a first step of forming a groove on a lead frame material before lead processing, at a portion to be a tip of the lead and on a board mounting surface side. And a second step of forming a solder plating on the front, back, and side surfaces of the lead frame material in which the groove is formed, and a third step of cutting the lead frame material with the groove of the solder plated lead frame and processing it into a lead shape. A method of manufacturing a lead of a resin-encapsulated semiconductor device, comprising: