JPH06204377A - Package for semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a package for semiconductor device which can achieve a proper packaging with the brazing material of an external lead and can achieve the packaging according to a socket at a low cost and with a long life and to obtain the manufacturing method. CONSTITUTION:Plating films 2a and 2b of such as nickel are formed on the entire surface of an external lead 2 provided on a package 1 for semiconductor device, and a gold plated film 2c is formed on top of them at the tip and base edge parts excluding a non-gold-plated film 2d which is secured at the center in the length direction of the external lead. Use of the gold plated film 2c at the tip part makes it possible to achieve a satisfactory soldering without any flow of solder to the base edge side. Also, by utilizing the gold plated film with a large base edge part area, the socket can be electrically connected and an inexpensive and long-life socket can be used. A conductive elastic body is fitted to the non-plated part 2c so that the middle part in the longer direction of the external lead can be covered and gold plating is performed by the electrolytic plating method with the conductive elastic body as a plating electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device package, and more particularly to a metal plating structure for external leads attached to the package and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as an external lead of a semiconductor device package having metal plating formed thereon, Japanese Patent Application Laid-Open No. 2-1.
There is one described in Japanese Patent No. 5662. This semiconductor device package has a package 21 as shown in FIG.
The external lead 22 is connected to the connection pad 23 provided on the substrate by brazing. The external lead 22 is made of phosphor bronze, and the nickel plating film 22 is formed on the entire surface thereof.
a is formed, and a gold plating film 22 is further formed on the surface of the tip of the
b is formed. Then, using the gold plating film 22b, the tip portions of the external leads are connected to the pads 29a of the printed board 29 by the solder 30.

As a method of forming the gold plating film 22b only on the tip portions of the external leads 22, in this publication, as shown in FIG. 8, the second cutting of the gold plating jig 24 formed of plastic resin is performed. External lead 22 in notch 24b
The mask 25 having the through hole 25a is positioned at a position corresponding to. After that, the semiconductor device package 21 on which the external leads 22 are formed is set on the gold plating jig 24. Specifically, the semiconductor device package 21 is positioned in the first notch 24a formed in the gold plating jig 24. With such positioning, only the tip of the external lead 22 projects from the through hole 25a of the mask 25. Then, when the semiconductor device package 21 and the mask 25 are positioned on the gold plating jig 24, they are positioned in the gold plating tank 26 in which the electroless gold plating is melted, and only the tip portions of the external leads 22 are gold plated.

The external lead 22 having the gold-plated film formed only on the tip portion in this manner is connected to the pad 29a of the printed circuit board 29.
If the solder 30 is connected to the solder 30, the solder 30 wets only the gold-plated film 22b at the tip of the external lead 22, so that the shape and amount of the solder 30 can be easily controlled. By the way, if gold plating is applied to the entire external lead, the solder flows to the base end side of the external lead, so the amount of solder at the tip bump decreases, and the solder expands to the side of the external lead.
The reliability of the solder joint will be significantly reduced.

[0005]

However, in the semiconductor device package having such a configuration, if the package is mounted on a socket, a problem is likely to occur. For example, in FIG.
FIG. 3 is a cross-sectional view of an example in which this type of semiconductor device package 21 is mounted in a socket. However, since the outer lead 22 has a gold plating film 22 b formed only on the tip end thereof, mechanical contact with the outer lead 22 is made. The contact of the socket 27 with the socket lead 28 for performing the above-mentioned procedure must be performed with the end faces abutting each other.

That is, in general, when electrical connection is made only by mechanical contact, in order to reduce the contact resistance at the contact portion, the surface of the contact portion is made of gold by utilizing the high ductility of gold. Many. Therefore, in the above-described structure, since the gold plating film 22b is formed only on the tip portions of the external leads 22, the tip surfaces of the external leads 22 are used as contact surfaces. Lead 2
8 is provided with a contactor 28b biased by a spring 28a, and the contactor 28b is urged by the force of the spring 28a.
There is no choice but to adopt a configuration in which b is brought into contact with the surface of the gold-plated film 22b at the tip of the external lead 22. However, the socket having such a structure has a problem that the structure becomes complicated, the cost becomes high, and the life becomes short. An object of the present invention is to provide a package for a semiconductor device, which enables suitable mounting with a brazing material and at the same time mounts with a socket at low cost and with a long life. Another object of the present invention is to provide a method for manufacturing a semiconductor device package, which is suitable for such mounting, and particularly a metal plating method for external leads.

[0007]

According to the present invention, an external lead provided in a semiconductor device package has a non-metal plated portion in which a metal plated film is not formed in an intermediate portion in the length direction. For example, a plating film of nickel or the like is formed on the entire surface of the external lead, and a gold plating film is formed on the plating film at the tip end portion and the base end portion excluding the intermediate portion in the length direction of the external lead. Further, the manufacturing method of the present invention,
A conductive elastic body was attached so as to cover the middle portion of the external lead provided in the semiconductor device package in the longitudinal direction, and the conductive elastic body was covered by the electroconductive plating method using the conductive elastic body as a plating electrode. A metal plating film is formed on the surface of the external lead except the part.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is an embodiment in which the present invention is applied to a pin grid array type package, and is a sectional structural view of an external lead of a semiconductor device package. The external leads 2 of the semiconductor device package 1 are made of a material having a thermal expansion coefficient similar to that of alumina ceramic which is a constituent material of the package 1 such as Kovar. A nickel film 2a is formed on the entire surface of the external lead 2 in advance by plating or the like, and the base end portion of the external lead 2 is brazed to a connection pad 3 formed on the package 1 by a silver copper braze 4 or the like. There is. In this case, it is preferable to form the nickel film 3a also on the surface of the connection pad 3 by electroless plating or the like. Then, the external lead 2
Then, a nickel-cobalt film 2b is formed by electrolytic plating or the like on the entire surface including the connection pad 3 and the protection pad 3 for protecting the silver-copper solder 4. Further, a gold plating film 2c is further formed on the surface of the external lead 2. The gold plating film 2c is formed on the tip and the base of the external lead 2, respectively, and between the tip and the base. The non-gold plated portion 2d having a length of 1/5 to 1/4 of the entire length of the outer lead 2 is secured.

FIG. 2 is a conceptual view showing a method of manufacturing the gold plating film 2c on the external lead. In the figure, 8
Is a gold plating tank, and the inside is filled with gold plating liquid. Then, as shown in FIG. 1, the external lead 2 is connected to the package 1 to form the nickel film 2a and the nickel-cobalt film 2b, and then 1/5 of the entire length of the external lead 2 is formed.
The external lead 2 is inserted into the conductive rubber sheet 5 having a thickness of ¼. The conductive rubber sheet 5 is provided with through holes 5a according to the arrangement of the external leads 2. The through holes 5a are provided with a size slightly smaller than the diameter of the external leads 2 so that the conductive rubber sheet 5 can be stretched. External lead 2 depending on sex
So that you can insert. This is to prevent a gold plating solution from entering by preventing a gap from being formed between the external lead 2 and the conductive rubber sheet 5. Further, the spacers 6 are attached to the semiconductor device package 1 and the conductive rubber sheet 5 so that the tips of the external leads 2 penetrate the conductive rubber sheet 5 by a length of 1/5 to 1/4 of the entire length thereof. Between the two. In this state, touch the conductive rubber sheet 5,
By attaching the plating electrode 7 and immersing it in the gold plating tank 8 and applying a voltage to the plating electrode 7, a gold plating film 2c is formed on the surface of the external lead 2 except for the through hole 5a portion of the conductive rubber sheet 5. It

FIG. 3 shows a state in which the semiconductor device package 1 thus formed is mounted on a printed circuit board by soldering. In the figure, the pad 9 provided on the printed circuit board 9
The external lead 2 is abutted on a, and the tip of the external lead 2 is connected to the pad 9a using the solder 10. At this time, since the non-gold-plated portion 2d exists between the tip portion and the base end portion of the external lead 2, the solder 10 wets the gold-plated film 2c at the tip portion and flows to the base end side. Since there is no solder, it becomes easy to keep the solder 10 on the pad 9a and control its shape.

On the other hand, when the semiconductor device package 1 having such a gold-plated film is mounted in a socket, a socket as shown in FIG. 4 can be used. In this socket, a socket lead 12 formed of two leaf springs is internally housed in a hole provided in a socket body 11, and the tip end portion thereof has increased springiness to reduce contact resistance with the external lead 2. Similarly, the curved portion 12a is provided. Therefore,
When the external lead 2 is inserted between the socket leads 12, the curved portion 12a of the socket lead 12 comes into contact with the base end portion of the external lead 2 due to the spring property, and comes into contact with the gold-plated film 2c at the base end portion. In this case, since the gold-plated film 2c at the base end portion is formed in a sufficient length region, a sufficient contact area with the socket lead 12 can be secured, and good contact with low contact resistance can be achieved. Incidentally, the socket having such a structure is most often used for a semiconductor device,
It is inexpensive and has a long life.

FIG. 5 is a diagram showing a second embodiment of the semiconductor device package of the present invention, in which an example applied to a flat type package is shown. In this package, the external lead 2A is projected in the horizontal direction from the package 1A and is bent and formed in a substantially crank shape. Then, the gold plating film 2c is formed on the tip end portion and the base end portion, but the gold plating film is not formed on the central portion of the inclined portion in the middle thereof, and the non-gold plating portion 2d is formed. . Therefore, this package is attached to the pad 9 of the printed circuit board 9.
Even when the solder 10 is connected to a, the solder 10 is wet only in the gold-plated film 2c at the tip end and does not flow to the gold-plated film 2c at the base end due to the non-gold-plated portion 2d.

FIG. 6 is a plan view schematically showing a manufacturing method for forming the gold plating film 2c on the external lead 2A of FIG.
Here, the rubber sheet 5A is attached to a substantially square frame 5b, and is fitted to a substantially central portion of an external lead (each external lead 2A is connected by a lead tie bar 2e) before being bent. There is. In this case, the rubber sheet 5A is provided with the external leads 2 so that the plating solution can be prevented from entering.
Roughness is provided according to the shape of A, and a more rigid frame 5
The shape is retained by pressing with b. Note that FIG.
Lead diver 2 connecting each external lead 2A like
When e is present, the lead diver 2e may be used to connect to the plating electrode. Also, the non-gold plated part 2d
It is preferable that the length dimension of is set shorter than the dimension of the inclined portion in FIG. 5 in consideration of the dimension variation when cutting or bending the external lead. In addition, in this 2nd Example, the thing equivalent to the 1st Example shown in FIGS. 1-4 is acquired as a basic effect, and the manufacturing method which abbreviate | omitted detailed description can also respond with an equivalent method. It is a thing.

[0014]

As described above, the semiconductor device package of the present invention has the non-metal-plated portion in which the metal-plated film is not formed at the intermediate portion in the lengthwise direction of the external lead. When mounting with brazing material,
By utilizing the wettability of the metal plating film provided on the tip of the external lead, the brazing material is prevented from flowing toward the base end side, and the shape change of the brazing material is completely suppressed, which enables suitable brazing. . Also, in the case of socket mounting, by using the metal plating film provided on the base end side, it is possible to use a socket composed of leaf springs, simplifying the socket structure and lowering the cost. it can. By the way, compared with the socket shown in FIG. 9, the socket used in the present invention is less than one tenth in price and more than three times in service life. In particular, a nickel or nickel-cobalt plating film is formed on the entire surface of the external lead, and a gold plating film is formed on the plating film at the tip and base ends of the external lead excluding the middle part in the length direction. By doing so, the wettability with the solder at the time of mounting can be improved, the flow of the solder can be prevented, and the contact resistance with the socket can be reduced.

Further, in the manufacturing method of the present invention, the conductive elastic body is attached so as to cover the intermediate portion in the lengthwise direction of the external lead,
A metal plating film is formed on the surface of the external lead except for the portion covered with the conductive elastic body by the electrolytic plating method using this conductive elastic body as a plating electrode. The part can be easily formed. Further, in this case, by using the conductive elastic body, it is possible to omit the electrode wire drawn from the internal signal wiring of the semiconductor device package as an electrode required for electrolytic plating. There is also an effect of reducing the stray capacitance between the signal wirings inside.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an external lead of a semiconductor device package of the present invention.

FIG. 2 is a conceptual diagram for explaining an external lead plating method according to the present invention.

FIG. 3 is a cross-sectional view showing a mounted state of the semiconductor device package of the present invention.

FIG. 4 is a cross-sectional view of a semiconductor device package of the present invention mounted in a socket.

FIG. 5 is a schematic sectional view of an external lead according to a second embodiment of the present invention.

FIG. 6 is a schematic plan view for explaining a method of plating the external leads of FIG.

FIG. 7 is a schematic cross-sectional view showing a mounted state of a conventional package.

FIG. 8 is a conceptual diagram for explaining a conventional external lead plating method in a package.

FIG. 9 is a sectional view of a conventional package mounted in a socket.

[Explanation of symbols]

 1, 1A Package 2, 2A External lead 2a Nickel plated film 2b Nickel / Cobalt plated film 2c Gold plated film 2d Non-gold plated part 5 Conductive rubber sheet 7 Plated electrode 9 Printed circuit board 10 Solder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsunori Suzuki 5-7-1, Shiba, Minato-ku, Tokyo NEC Corporation

Claims (3)

[Claims] 1. A package for a semiconductor device in which a metal plating film is formed on the surface of an external lead provided in a package, wherein the external lead is a non-metal in which a metal plating film is not formed in an intermediate portion in the length direction. A semiconductor device package having a plated portion. 2. A plating film of nickel or the like is formed on the entire surface of the external lead, and a gold plating film is formed on the plating film at the front end portion and the base end portion of the outer lead excluding the middle portion in the longitudinal direction. The package for a semiconductor device according to claim 1, wherein 3. A conductive elastic body is attached so as to cover an intermediate portion in the lengthwise direction of an external lead provided in a semiconductor device package, and the conductive elastic body is formed by an electroplating method using the conductive elastic body as a plating electrode. A method of manufacturing a package for a semiconductor device, characterized in that a metal plating film is formed on the surface of the external lead excluding the portion covered with the elastic body.