JP2002246721A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent bonding strength from lowering, after use over a long term by performing void-free soldering at the time of mounting a surface mounting semiconductor on a printed wiring board. SOLUTION: The lead 2 of a semiconductor device 7 is provided with fine holes 3, and solder 4 is thermally fused in a reflow furnace, thus bonding the lead 2 of the semiconductor device 7 to the copper land 6 of a printed wiring board 5. Since bubbles generated in the solder are discharged through the fine holes 3, void-free soldering is ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape of leads of a surface-mounted semiconductor device mounted on a printed wiring board in electronic equipment.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and lighter, printed wiring boards for controlling the devices have also been required to be smaller, and the number of electronic components mounted on the printed wiring boards has increased from insertion type to surface mount type. Implementation is progressing. For this reason, the solder used as the connection material is changed from bar solder to solder paste.
As for the heating device, the ratio of the flow type to the reflow type is increasing.

Under these circumstances, mounting of electronic components on a printed wiring board involves printing a predetermined amount of solder paste on a copper land portion of the printed wiring board with a metal mask, mounting the electronic components thereon, and mounting a reflow furnace or the like. This is done by heating, melting, and solidifying the solder portion.

FIG. 4A is a top view showing a state in which a surface-mount type semiconductor device is mounted on a printed wiring board.
4 is provided with a lead 32 for connecting to the copper land portion provided on the substrate 4, and the copper land portion and the lead 32 are connected by solder 33.

[0005]

However, if the temperature profile of a reflow furnace for soldering electronic components to a printed wiring board is not optimal, the solvent and the like in the flux contained in the solder paste will vaporize, Is discharged from the molten solder to the outside, but a part remains in the molten solder, and when solidified, voids are generated in the solder.

[0006] That is, the A-
The cross section A is shown in FIG. 4 (b). The gas generated during the reflow cannot escape to the outside until the solder solidifies, and a void is formed inside the solder 33 between the lead 32 and the copper land 35. It becomes 36. In the solder joint including the voids 36, there is a problem in that the joint strength is reduced, and in the long-term use of the product, long-term reliability is reduced, such as cracks progressing due to bubbles as a starting point due to thermal strain or impact. I was

[0007] As a measure for preventing the generation of bubbles, a temperature profile is changed so as to prolong the solder melting time during reflow. However, thermal damage to electronic components mounted on a printed wiring board is increased. There has been a problem that the reliability of the electronic component is reduced.

[0008]

In order to solve the above-mentioned problems, a semiconductor device according to the present invention is characterized in that a hole is provided in a soldering portion of a lead in a surface-mount type semiconductor device.

According to the present invention, by providing a hole in the portion of the lead to be soldered, it is possible to discharge bubbles generated during reflow through the hole to the outside of the solder. It is possible to provide a printed wiring board which has no air bubbles at the interface of the copper land portion and is soldered with high connection reliability.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is characterized in that a hole is provided in a part of a surface-mount type semiconductor device to which a lead is to be soldered, and the lead is printed using solder. When soldering electronic components to the wiring board,
Air bubbles generated by vaporization of the resin etc. in the solder during reflow are released from the solder through the holes provided in the lead, so that there is no air bubble connection at the interface between the lead and the solder and the interface between the solder and the copper land It has the effect of increasing reliability.

According to a second aspect of the present invention, in a surface-mount type semiconductor device, a protrusion is provided on a portion to be soldered of a lead so as to be convex in a direction in contact with a printed wiring board. When a surface-mount type semiconductor device is mounted, the solder is pushed out by the protrusion, and bubbles generated during reflow rise along the lead of the semiconductor device, and the protrusion is formed. The solder is released from the solder through the holes provided around the lead, eliminating air bubbles at the interface between the lead and the solder, and the interface between the solder and the copper land, and increasing the contact area between the solder and the lead to increase connection reliability. It has the effect of doing.

According to a third aspect of the present invention, in a surface-mount type semiconductor device, a projection is provided at a portion to be soldered of a lead so as to be concave in a direction in contact with a printed wiring board, and near a top of the projection. When the surface-mount type semiconductor device is mounted, the solder enters the protrusion and bubbles generated during reflow are removed from the solder through the hole near the top of the protrusion. When released outside, there is no bubble at the interface between the lead and the solder and the interface between the solder and the copper land portion, and the contact area between the solder and the lead is increased, thereby improving the connection reliability.

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a top view and a sectional view of a semiconductor device according to a first embodiment of the present invention in a mounted state.

The present invention is characterized in that a hole is provided in a portion of a surface mount type semiconductor device to which a lead is to be soldered.

That is, as shown in FIG. 1, a semiconductor device 7 of the present invention comprises a lead 2 for connecting a semiconductor chip (not shown) in a mold resin 1 and a copper land 6 of a printed wiring board 5. The lead 2 is formed of a copper plate or an iron-based material to efficiently release heat generated from the semiconductor chip or to secure connection strength. The lead 2 is finely formed by etching or pressing. The hole 3 is provided. The semiconductor device 7 includes a printed wiring board 5
Are connected to the leads 2 by solder 4 to ensure electrical and strength reliability.

The connection by the solder 4 is performed on the printed wiring board 5
The solder 4 which is a mixture of a flux and a solder alloy is printed and supplied to the copper land 6, and the semiconductor device 7 is mounted so that the lead 2 of the semiconductor 7 and the copper land 6 coincide with each other, for example, by a heating device such as a reflow furnace. By heating and cooling the printed wiring board 5, the solder 4 is melted and solidified, and the connection between the lead 2 and the copper land 6 is completed.

In a conventional semiconductor device, when the semiconductor device is heated and melted in a reflow furnace in order to connect the lead of the semiconductor device and the copper land of the printed wiring board using solder, the solvent and resin contained in the flux in the solder are vaporized. Bubbles move in the solder, but do not go outside because they are blocked by semiconductor leads, and become voids after solidification of the solder. Soldering that includes voids has the problem that thermal stress is applied to the solder due to heating and cooling during operation of the product, causing bubbles to form as starting points, cracking, and lowering the bonding strength and lowering connection reliability. Was.

In the semiconductor device 7 of the present invention, the fine holes 3 are provided in the leads 2. When the leads 2 of the semiconductor device are connected to the copper lands of the printed wiring board using solder, the solder is heated and melted in a reflow furnace. As the temperature of the solder rises, the solvent or resin contained in the flux in the solder vaporizes, bubbles move in the solder toward the lead 2, and bubbles are discharged out of the solder from the fine holes 3 provided in the lead 2, After the solidification, it is possible to obtain a solder without voids as shown in the sectional view of FIG. Also, even if the fine holes 3 are provided in the leads 2, the solder does not enter the fine holes 3, so that the strength of the leads does not decrease.

As described above, by providing fine holes in the leads of a semiconductor device, it is possible to perform soldering without holes without changing the temperature profile during reflow, and to prevent thermal shock during actual operation. It is possible to provide a printed wiring board that has been soldered without high strength and with high connection reliability.

(Embodiment 2) FIG. 2 is a top view and a sectional view in a mounted state of a semiconductor device according to a second embodiment of the present invention.

The present invention is characterized in that a projection is provided on a soldered portion of a lead in a surface mounting type semiconductor device so as to be convex in a direction in contact with a printed wiring board, and a hole is provided around the projection. Is what you do.

That is, in FIG. 2, a semiconductor device 18 of the present invention is provided with a lead 12 for connecting a semiconductor chip (not shown) in a mold resin 11 and a copper land 17 of a printed wiring board 16. The lead 12 is provided with a recess 14 by press working, and a fine hole 13 around the recess 14 by etching or press working. In the semiconductor device 18, the copper lands 17 provided on the printed wiring board 16 and the leads 12 are connected with the solders 15 to ensure electrical and strength reliability.

In the semiconductor device 18 of the present invention, the leads 12
A recess 15 and a fine hole 13 are provided, and a solder 15 is printed and supplied to a copper land 17 of a printed wiring board 16. It is pushed around by the recess 14.

When soldering is performed using a reflow furnace in this state, the solvent and resin contained in the flux in the solder are vaporized as the temperature of the solder is increased, and bubbles move in the solder to the lead 12 side. The solder is discharged out of the solder through the fine holes 13 provided in the periphery similarly to the first embodiment. By providing the depression, bubbles are easily collected, the contact area between the lead 12 and the solder 15 is increased, the bonding strength is increased, and more reliable soldering is possible.

As described above, by providing the recesses and the fine holes in the leads of the semiconductor device, it becomes possible to perform soldering without voids and increase the contact area between the solder and the leads.
It is possible to provide a printed wiring board that has a high bonding strength and is soldered with high connection reliability.

(Embodiment 3) FIG. 3 is a top view and a cross-sectional view of a semiconductor device according to a third embodiment of the present invention in a mounted state.

The present invention is characterized in that a protrusion is provided at a soldered portion of a lead in a surface mounting type semiconductor device so as to be concave in a direction in contact with a printed wiring board, and a hole is provided near the top of the protrusion. It is assumed that.

That is, in FIG. 3, a semiconductor device 28 of the present invention is provided with a lead 22 for connecting a semiconductor chip (not shown) in a mold resin 21 and a copper land 27 of a printed wiring board 26. The lead 22 is provided with a projection 24 by pressing, and a fine hole 23 near the top of the projection 24 by etching or pressing. The semiconductor device 28 includes the printed wiring board 26
Are connected to the leads 22 by solders 25 to ensure electrical and strength reliability.

In the semiconductor device 28 of the present invention, the leads 22
Are provided with projections 24 and fine holes 23, and solder 25 is printed and supplied to copper lands 27 of the printed wiring board 26, and when the leads 22 of the semiconductor device 28 and the copper lands 27 are mounted so as to match, the solder 25 It gathers on the projection 24. When soldering is performed using a reflow furnace in this state, the solvent and resin contained in the flux in the solder vaporize as the temperature of the solder rises, and air bubbles move in the solder toward the lead 22 along the inner surface of the projection 24. And solder 25 through hole 23
The solder is discharged to the outside, and as shown in the cross-sectional shape of FIG. By providing the projections 24, air bubbles are easily collected, air bubbles are easily moved along the inner surface, the contact area between the lead 22 and the solder 25 is increased, and the bonding strength is increased, so that more reliable soldering is possible. Become.

As described above, by providing protrusions and fine holes in the leads of a semiconductor device, it is possible to perform soldering without voids, increase the contact area between the solder and the leads, increase the bonding strength, and improve the connection reliability. It is possible to provide a printed wiring board that is highly soldered.

[0032]

As described above, in the semiconductor device of the present invention, by providing fine holes in the leads, bubbles generated in the solder during reflow are released out of the solder through the holes, and the solder without voids is formed. This makes it possible to provide a printed wiring board with high reliability, which prevents a decrease in bonding strength.

Also, in the semiconductor device of the present invention, since the recess and the fine hole or the protrusion and the fine hole are provided in the lead, bubbles generated in the solder during the reflow can be discharged out of the solder through the hole. It is possible to provide a printed wiring board with high connection reliability by increasing the bonding area between the solder and the lead.

[Brief description of the drawings]

FIG. 1 is a top view and a cross-sectional view of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a top view and a cross-sectional view of a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a top view and a cross-sectional view of a semiconductor device according to a third embodiment of the present invention.

FIG. 4 is a top view and a cross-sectional view of a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold resin 2 Lead 3 hole 4 Solder 5 Printed wiring board 6 Copper land 7 Semiconductor device 11 Mold resin 12 Lead 13 Hole 14 Depression 15 Solder 16 Printed wiring board 17 Copper land 18 Semiconductor device 21 Mold resin 22 Lead 23 Hole 24 Projection 25 Solder 26 Printed wiring board 27 Copper land 28 Semiconductor device 31 Mold resin 32 Lead 33 Solder 34 Printed wiring board 35 Copper land 36 Void

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Nagashima 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 5E319 AA03 AB01 AC01 BB05 CC36 GG03 5E336 AA04 CC02 CC06 CC07 EE03 GG06

Claims (3)

[Claims] 2. A semiconductor device according to claim 1, wherein a hole is provided in a portion of the surface-mount type semiconductor device where a lead is to be soldered. 2. A semiconductor device according to claim 1, wherein a protrusion is provided on a soldered portion of the lead in the surface mounting type semiconductor device so as to be convex in a direction in contact with the printed wiring board, and a hole is provided around the protrusion. apparatus. 3. A surface mounting type semiconductor device, wherein a projection is provided at a soldered portion of a lead so as to be concave in a direction in contact with a printed wiring board, and a hole is provided near a top of the projection. Semiconductor device.