JPH10144845A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make firm junctions of outer leads of a semiconductor device even if thin and fine outer leads are formed at a narrow pitch. SOLUTION: Within a semiconductor device 1 provided with a body 2 and a plurality of outer leads 3 externally extruded from the body 2, at least the underside 3c and both sides 3b of an outer lead 3 are plated. In such a constitution, an outer lead 3 is formed to erect its tip part 32b up from the main body 2 side part 32a continuous with this tip part 32b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having external leads.

[0002]

2. Description of the Related Art As a conventional semiconductor device, SOP (Sm
all Outline Package) type, QFP (Quad Flat
Packege) type and the like are known. FIG. 9 shows an example of the SOP type semiconductor device, and FIG. 10 is an enlarged view of a main part of FIG. As shown in the figure, the semiconductor device 51 includes a main body 52 formed of a resin-sealed package having a substantially rectangular shape in a plan view, and a plurality of external leads 53 extending from two opposing side surfaces of the main body 52 to the outside. It is configured. When mounting the semiconductor device 51 on a mounting substrate formed of, for example, a circuit board, the external leads 53 are bonded to the bonding surface of the mounting substrate via solder. For example, it comprises a lead base 531 extending downward from the main body 52 and a flat lead end 532 extending from the lead base 531 at a substantially right angle in a direction opposite to the main body 52.

The external leads 53 are formed by plating after the main body 52 is formed by a resin sealing process, cut from the frame of the lead frame, and further bent. Therefore, the length of the external lead 53 is determined by the above-mentioned cutting, and the cut surface is the tip surface 53 of the external lead 53.
a. Further, since the external lead 53 is cut after the plating process, the upper surface 53b, the side surface 53c, and the lower surface 53d of the external lead 53 are plated, but the distal end surface 53a is an unplated surface. In such a semiconductor device, the external leads have recently become thinner and thinner in any of the SOP type, the QFP type and the like, and furthermore, as the mounting density of the semiconductor device on a mounting substrate increases, the external leads become smaller. The pitch is also getting smaller.

[0004]

As described above, in the conventional semiconductor device, the external leads are becoming thinner and thinner, and the pitch between the external leads is becoming narrower. For this reason, the solder wettability of the external lead when joining the external lead to the surface to be joined via solder has a great effect on the joining strength.

For example, as shown in FIG.
Since the lower surface 53d is plated and has good wettability with the solder 70, when the external lead 53 is joined to the surface 62 to be joined of the mounting substrate 61 by the solder 70, the lower surface 53d crawls on the lower surface 53d as shown in FIG. Then, the solder 70 spreads. On the other hand, the tip surface 53a is not plated and the solder 7
Since the wettability with 0 is poor, the solder 70 does not spread.
Therefore, the tip surface 53a and the mounting substrate 61 cannot be joined with a sufficient amount of solder, and as a result, solder peeling occurs, and the reliability of a product configured by mounting the semiconductor device 51 on the mounting substrate 61 is improved. Worsens. Therefore,
Even if the external leads are formed to be thin, thin, and at a narrow pitch, there is a strong demand for the development of a semiconductor device capable of firmly joining the external leads and the surface to be joined.

[0006]

According to the present invention, there is provided a semiconductor device having a main body and a plurality of external leads extending from the main body to the outside. The side is plated,
The distal end portion of the external lead is formed so as to rise upward from the distal end portion with respect to the main body side portion that follows the distal end portion.

In the present invention, since the front end portion of the external lead is formed so as to rise upward with respect to the main body side portion which is continuous with the external lead, when the semiconductor device is arranged on the surface to be joined, The lower surface of the lead-side portion is located above the lower surface of the body-side portion. In addition, since at least the lower surface and the side surfaces of the external leads are plated, at least these surfaces are surfaces having good solder wettability. Therefore, when the joined surface and the external lead are joined by solder, a phenomenon that the solder creeps up on the lower surface of the tip side portion occurs, and the solder creeps up between the lower surface of the tip side portion and the joined surface. A part is formed. Also, the solder creeps up on the side surface of the portion on the tip side, and a creeping-up portion of the solder is formed between them.

[0008]

Embodiments of a semiconductor device according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an essential part showing one embodiment of a semiconductor device according to the present invention. As shown in FIG. 1, the semiconductor device 1 includes a main body 2 having a substantially rectangular shape in plan view,
External leads 3 extending to the outside from the side surface 2a
It is comprised including.

The external lead 3 includes a lead base 31 extending downward from the side surface 2a of the main body 2 and a lead end 32 extending from the lower end of the lead base 31 and bent at a substantially right angle to the opposite side to the main body 2. It is configured. Lead end 3
2 is a portion 32 a of the main body 2 extending from the lead base 31.
And a portion 32b on the front end side which is continuous with the portion. The portion 32a on the main body 2 side is formed flat. The tip portion 32b is formed to be bent upward at an angle of about 90 ° with respect to the portion 32a on the main body 2 side. Therefore, the external lead 3 is configured such that the lead end portion 32 has a substantially L-shape when viewed from the side, and the distal end surface 3d faces upward. In addition, the entire surface of the external lead 3 except for the distal end surface 3d, that is, the upper surface 3a, the side surface 3b, and the lower surface 3c are plated with, for example, solder.

In such a semiconductor device 1, since the portion 32b on the distal end side of the external lead 3 is formed so as to rise above the portion 32a on the main body 2 side, as shown in FIG. When the semiconductor device 1 is arranged on the surface 62 to be joined, the tip 32 of the external lead 3
The lower surface 3c in b is located above the lower surface 3c in the portion 32a on the main body 2 side. Further, the lower surface 3c of the lead base 31 is also located above the lower surface 3c of the portion 32a on the main body 2 side. In addition, the lower surface 3c of the external lead 3 has good solder wettability.

Therefore, when the surface 62 to be joined and the external lead 3 are joined by the solder 70, the solder 70 crawls on the lower surface 3 c on the lower end side of the lead base 31, and
This leads to creeping on the lower surface 3c of the portion 32b on the tip end side of the lead end 32. As a result, a solder creeping-up portion 71 is formed between the lower surface 3c on the lower end side of the lead base 31 and the surface 62 to be bonded, and between the lower surface 3c of the tip portion 32b and the surface 62 to be bonded. Also, the side surface 3b on the lower end side of the lead base 31, the side surface 3b of the portion 32a on the main body 2 side of the lead end portion 32, and the side surface 3b of the distal end portion 32b are surfaces having good solder wettability. As shown in FIG. 3, which is a cross-sectional view of the side portion 32a, the solder 70 also creeps up on these side surfaces 3b, and a solder creeping-up portion 71 is formed between these and the surface 62 to be joined.

Therefore, when bonding the external lead 3 and the surface 62 to be bonded, compared to the conventional semiconductor device, the solder 7 involved in bonding the portion 32b on the distal end side to the surface 62 to be bonded.
Since the amount of 0 can be increased, the external lead 3 and the surface 62 to be joined can be soldered with high joining strength.

In such a semiconductor device 1, the tip 32 b of the external lead 3 rises from the tip 32 a of the main body 2, so that the tip 32 b reinforces the tip 32 a of the main body 2. ing. For this reason, the external lead 3 has a higher mechanical strength than the external lead of the conventional semiconductor device shown in FIG. Therefore, the conventional external lead is easily deformed even when a small external force is applied, but the external lead 3 can greatly suppress the deformation due to the external force. From this, it is possible to improve the reliability of the bonding portion when the external lead 3 is bonded to the surface 62 to be bonded. As described above, according to the semiconductor device 1 of this embodiment, the reliability of a product configured by mounting the semiconductor device 1 on the mounting substrate 61 can be improved.

In the above-described embodiment, an example has been described in which the main body side portion and the front end side portion of the external lead are formed in a substantially L shape in a side view.
It is only necessary that the front end portion be formed in a state of rising above the main body side portion, and the present invention is not limited to the above example.
For example, the external leads 3 may be formed as in the semiconductor device 1 of the first modified example shown in FIG.

That is, in the semiconductor device 1 shown in FIG. 4, the external lead 3 is formed by bending the lower end of the lead base 31 and the lead end 32 into a substantially U-shape when viewed from the side.
Therefore, the lead base 31 and the portion 32a of the lead end 32 on the main body 2 side are formed in a continuous arc shape. Along with this, a portion 32a of the lead end 32 on the main body 2 side and a portion 32b on the distal end side are formed in an arc shape, and the distal end surface 3c is formed in a shape facing upward.

In the semiconductor device 1, the portion 3 on the main body 2 side
2a and the distal end portion 32b are formed so as to form an arc. Therefore, when the surface 62 to be joined and the external lead 3 are joined as shown in FIG.
A large space is formed between c and the surface 62 to be joined. As a result, as compared with the external leads 3 of the semiconductor device 1 shown in FIG.
Between the solder creeping portion 71 and the solder 7
The amount of zero can be increased. Similarly, the lead base 31 and the lead end 32 are formed so as to form an arc, and the lower surface 3c on the lower end side of the lead base 31 and the main body 2 are formed.
Since a large space is formed between the lower surface 3c of the side portion 32a and the surface 62 to be joined, the amount of the solder 70 in the creeping-up portion 71 of the solder 70 formed therebetween can be increased.

Therefore, when joining the external lead 3 and the surface 62 to be joined, the external lead 3 and the surface 62 to be joined can be soldered with higher joining strength. In such a semiconductor device 1 as well, the tip 32b of the external lead 3 rises from the portion 32a of the main body 2, and the mechanical strength of the portion 32a of the main body 2 is increased by the tip 32b. Therefore, deformation of the external lead 3 due to external force can be prevented. Therefore, it goes without saying that the reliability of the joint between the external lead 3 and the surface 62 to be joined can be improved.

In the semiconductor device 1 described with reference to FIG. 1, the tip 32b of the external lead 3 is bent at an angle of approximately 90 ° with respect to the portion 32a of the main body 2 side. However, it is needless to say that the angle is not limited to 90 ° as long as the portion 32b on the tip side is formed so as to rise above the portion 32a on the main body 2 side. For example, as in the semiconductor device 1 of the second modified example shown in FIG. May be formed.

Also in this semiconductor device 1, when the surface 62 to be bonded and the external lead 3 are bonded as shown in FIG.
Since a large space is formed between the lower surface 3c of the distal portion 32b and the surface 62 to be joined, the lower surface 3c of the distal portion 32b is smaller than the external lead 3 of the semiconductor device 1 shown in FIG. It is possible to increase the amount of the solder 70 in the solder creeping portion 71 formed between the surface 70 and the surface 62 to be joined. Therefore, when joining the external lead 3 and the surface 62 to be joined, the external lead 3 and the surface 62 to be joined can be soldered with higher joining strength. Further, since the mechanical strength of the portion 32a on the main body 2 side is increased by the portion 32b on the tip side of the external lead 3, the external lead 3
Can be prevented as in the previous embodiment.

Further, in the above embodiment and the first and second modifications, the distal end surface 3d of the external lead 3 is made of a non-plated surface. However, the external lead of the present invention has at least the lower surface and the side surface plated. Should be fine. Therefore, the tip surface may be plated.

For example, in the external lead 3 of the semiconductor device 1 of the second modified example shown in FIG. 6, if the front end face 3d is plated, the front end face 3d also has good solder wettability. Therefore, as shown in FIG.
Then, when the external lead 3 and the surface 62 to be joined are joined by the solder 70, the solder 70 creeps up to the tip surface 3 d, so that the solder creeping formed between the tip portion 32 b and the surface 62 to be joined. The amount of the solder 70 in the rising portion 71 can be increased. Therefore, external leads 3
When joining with the surface 62 to be joined, they can be joined more firmly, so that the reliability of this joint portion can be further improved.

[0022]

As described above, according to the semiconductor device of the present invention, the front end portion of the external lead is formed so as to rise upward with respect to the main body side portion which is continuous with the external lead portion. When soldering the external lead to the surface to be bonded of the mounting substrate, the creeping-up portion of the solder can also be formed between the front end portion and the surface to be bonded. As a result, the amount of solder involved in joining the front end portion and the surface to be joined can be increased, so that the external lead and the surface to be joined can be soldered with high joining strength.
Therefore, even if the external leads are thin and thin, and formed at a narrow pitch, the reliability of the joint between the external leads and the surface to be bonded can be improved, and by mounting the semiconductor device on the substrate to be mounted, The reliability of the configured product can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of an essential part showing one embodiment of a semiconductor device of the present invention.

FIG. 2 is a cross-sectional view showing a bonding state between an external lead and a surface to be bonded in the embodiment.

FIG. 3 is a cross-sectional view showing a main body side portion of a lead end in a joined state.

FIG. 4 is an essential part perspective view showing a first modification of the embodiment.

FIG. 5 is a cross-sectional view showing a bonding state between an external lead and a surface to be bonded in a first modified example.

FIG. 6 is an essential part perspective view showing a second modification of the embodiment.

FIG. 7 is a cross-sectional view showing a bonding state between an external lead and a surface to be bonded in a second modified example.

FIG. 8 is a sectional view illustrating a third modification of the embodiment.

FIG. 9 is a perspective view illustrating an example of a conventional semiconductor device.

FIG. 10 is an enlarged view of a main part of a conventional example.

FIG. 11 is a diagram showing a bonding state between an external lead and a surface to be bonded in a conventional semiconductor device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Semiconductor device 2 Main body 3 External lead 3
b Side surface 3c Lower surface 3d Tip surface 32a Body side portion 32b Tip side portion

Claims (3)

[Claims] 1. A semiconductor device comprising: a main body; and a plurality of external leads extending from the main body to the outside, wherein the external lead has at least a lower surface and side surfaces plated, and the external lead The semiconductor device is characterized in that a tip portion thereof is formed so as to rise upward with respect to the portion of the main body which is continuous with the tip portion. 2. The external lead is formed in a shape in which the distal end portion and the main body side portion are continuously formed in an arc shape in a side view, or the external lead is formed on the distal end side with respect to the main body side portion. 2. The semiconductor device according to claim 1, wherein the portion is formed in a shape bent at an angle. 3. The semiconductor device according to claim 1, wherein a tip end surface of said external lead is a plated surface.