JPS60257549A - Semiconductor device - Google Patents

Abstract

PURPOSE:To coat an external connecting lead excellently with solder by forming a recessed section opened in the width direction to both side edges of the external connecting lead, the surface thereof is coated with solder. CONSTITUTION:The depth of notch of a recessed section 11 is inhibited to one fifth or less of lead width in consideration of the flexural strength of a lead material, and molten solder is introduced into the recessed section on solder coating. When a semiconductor device, external connecting leads 2, 3 and 4 therein are positioned in a tub 7, is pulled up, solder coating films 8 in nose sections are not thickened as compared to sections in the vicinity of a molding section 5 as seen in conventional devices because solder under the state of semi- solidifying flowing in the direction of the noses of the external connecting leads is introduced into the recessed sections 11, and the solder coating films 8 in approximately the same thickness are formed on the surfaces of the external connecting leads 2, 3 and 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor device suitable for implementation in semiconductor products such as small- and medium-power silicones.

[Prior art]

Conventionally, this type of semiconductor device has been constructed as shown in FIG. External connection leads 5 are made of thin pieces and the surfaces thereof are covered with solder. Reference numeral 5 designates a mold portion for resin-sealing semiconductor elements (not shown) connected to these leads 2, 3 and 4. Note that copper alloy is usually used as the material for the heat sink 1 and the external connection leads 2, 3.4, and the surface thereof is coated with a metal such as nickel to a thickness of 2 to 5 microns. Furthermore, semiconductor devices are usually manufactured in series in a plurality to automate the manufacturing line, and are separated from each other after the semiconductor elements are sealed with resin.

When a customer mounts a semiconductor device configured in this manner on a board, a solder coating process is applied to the plated surface of the external connection leads to facilitate soldering of the external connection leads 2, 3, and 4. be done.

This solder coating method requires solder coating.

Although there are methods such as solder dipping, the solder dipping method is generally adopted in consideration of its workability and reliability.

When this solder immersion method is used, as shown in FIG. 2, after the external connection leads 2, 3 and 4 are immersed in a bath 7 in which the solder 6 is melted to the desired part to be coated with solder, the semiconductor device is pulled upward. External connection leads 2 and 3
and 4 solder coating can be performed. In this case, as a pretreatment to facilitate solder coating, the external connection leads 2, 3, and 4 are immersed in dilute hydrochloric acid for a few seconds to remove the oxide on the surface of the nickel coating applied to the lead surface, and remove the nickel coating. The surface must be kept clean. Further, the solder 6 in the bathtub 7 is normally □lead-tin eutectic solder, and the temperature is controlled at 280°C.

In the solder dipping method carried out in this manner, when the semiconductor device with the external connection leads 2, 3, and 4 is pulled up from the bath 7, semi-solidified solder flows toward the tips of the leads, as shown in FIG. The solder coating film 8 at the tip portion is thicker than the portion near the mold portion 5.

Therefore, when mounting a conventional semiconductor device on a board (not shown), it is difficult to insert the external connection leads 2, 3, and 4 into holes (not shown) provided in the board, and this insertion work is difficult. J' was even more problematic when automated.

1'1 J In other words, the hole diameter of the board is limited in order to maintain the high density of the board, and the hole pitch is designed to correspond to the pitch of the external connection leads 2, 3, and 4. This is because

[Summary of the invention]

The present invention has been developed in view of the above circumstances, and has an extremely simple configuration in which recesses opening in the width direction are provided on both sides of the external connection lead whose surface is coated with solder. The present invention provides a semiconductor device that can perform satisfactorily. Hereinafter, the configuration and the like will be explained in detail with reference to embodiments shown in the drawings.

[Embodiments of the invention]

FIG. 4 is a cross-sectional view showing a semiconductor device according to the present invention, and FIG.
Components that are the same as those in FIGS. 3 to 3 are designated by the same reference numerals, and detailed explanations will be omitted. In the same figure, what is indicated by the reference numeral 11 is a recessed portion opening in the width direction, which is provided on both side edges of the external connection leads 2.3 and 4, and each is positioned at a different position in the longitudinal direction of the lead. It is being The depth of cut of these recesses 11 is suppressed to 1/5 or less of the lead width in consideration of the bending strength of the lead material, and molten solder is introduced into the recesses during solder coating.

In the semiconductor device configured in this manner, when the semiconductor device with the external connection leads 2, 3, and 4 is pulled up from the bathtub 7, semi-solidified solder flowing toward the tips of the external connection leads is introduced into the recess 11. Therefore, the solder coating film 8 does not become thicker at the tip end than in the vicinity of the mold part 5 as in the past, and the surfaces of the external connection leads 2.3 and 4 have approximately the same thickness. A third solder coating film 8 is formed.

In this embodiment, an example is shown in which the recesses 11 are provided on both side edges of the external connection leads 2, 3, and 4, respectively.
The present invention is not limited to this, and it goes without saying that a plurality of them may be provided depending on the amount of solder flowing into the recess 11.

〔Effect of the invention〕

As explained above, according to the present invention, recesses opening in the width direction are provided on both sides of the external connection leads whose surfaces are covered with solder, so that a semiconductor device whose external connection leads are in a solder bath can be lifted up. At times, semi-solidified solder flowing toward the tip of the external connection lead is introduced into the recess, and the external connection lead can be well coated with solder. Therefore, when mounting a semiconductor device on a substrate, it is possible to easily insert external connection leads into holes provided in the substrate.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a conventional semiconductor device, FIG. 2 is a cross-sectional view showing how the external connection leads of the semiconductor device are coated with solder, and FIG. 3 is a cross-sectional view showing the semiconductor device with the external connection leads coated with solder. , FIG. 4 is a sectional view showing a semiconductor device according to the present invention. 2, 3. 4... External connection lead, 11...
recess. Agent Masuo Oiwa

Claims (1)

[Claims] 1. A semiconductor device comprising an external connection lead connected to a semiconductor element and whose surface is covered with solder, characterized in that a recess opening in the width direction is provided on both side edges of the external connection lead.