JPH0590348A - Film carrier and semiconductor device using same - Google Patents

Abstract

PURPOSE:To provide a film carrier and a semiconductor device which can prevent solder used to connect the film carrier mounting a semiconductor chip to an external board from flowing into the joint of the semiconductor chip. CONSTITUTION:A lead 1 on a film carrier is spread one after the other with a metal lower layer 3 poor in wettability to solder 8 and a metal upper layer 4 rich in wettability to it; further, the metal upper layer 4 is partially removed to form a region A which prevents inflow of solder 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film carrier and a semiconductor device using the film carrier.

[0002]

2. Description of the Related Art Conventionally, a method using a film carrier has been adopted as one of the methods for mounting a semiconductor element. In the so-called outer lead bonding for connecting this film carrier to an external substrate, a conductive medium metal is used. Solder is used. On the other hand, as electronic devices have become thinner and smaller and lighter in recent years, devices and equipment that use a large number of semiconductor devices require inner leads and outer layers to be mounted because the semiconductor elements must be mounted at high density on a substrate having a fixed area. For both leads, the pitch between leads tends to be narrowed, and the distance between the inner lead bonding portion and the outer lead bonding portion tends to be as short as possible.

However, when the distance between the bonding portions is shortened, the solder used for mounting the film carrier on the external substrate flows from the wettability to the mounting and connection portions of the semiconductor element through the leads and the semiconductor. This may cause a short circuit between the elements and adversely affect the connection reliability. Further, when the IC has a solder bump, it may not be able to be sufficiently connected due to a shortage of the required amount of solder to the connecting portion between the IC and the lead due to the outflow to another portion. Therefore, in order to prevent the inflow of solder into each connection portion, a means such as covering and protecting the connection portion of the semiconductor element with an insulating resin or plating a metal layer having poor wettability with respect to the solder on the lead surface is used. However, it is difficult to design and manufacture a film carrier in which the inner lead bonding part and the outer lead bonding part are close to each other as described above, and the reliability of the connection part is improved. There is a risk of deterioration in sex.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems in the above-mentioned conventional method, and when the semiconductor element mounting portion and the external substrate connecting portion are close to each other, the external substrate is connected at the time of connecting the external substrate. Provide a film carrier having a structure capable of surely preventing the used solder from flowing into a semiconductor element mounting portion, and mounting a semiconductor element using the film carrier, and a semiconductor device mounting the same on an external substrate The purpose is to do.

[0005]

The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, have found that the lead surface of the film carrier has a metal layer having poor wettability with respect to solder and a wettability. It has been found that the above object can be achieved by laminating a good metal layer and partially exposing a metal layer having poor wettability in order to prevent the inflow of solder, and completed the present invention.

That is, according to the present invention, in a film carrier having a semiconductor element mounting lead on one surface of an insulating film, the surface of the lead is a metal lower wettability to solder and a metal good wettability to solder. A film carrier, in which an upper layer is sequentially formed, a metal upper layer on a lead surface in an area outside the semiconductor element mounting portion is partially removed, and a metal lower layer is exposed, and a semiconductor element on the film carrier. And a semiconductor device in which a semiconductor element is placed and connected to the film carrier and is connected to a circuit wiring on an external substrate.

[0007]

Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a partial sectional view showing a state in which a semiconductor element is placed and connected using the film carrier of the present invention. As is clear from FIG. 1, the film carrier of the present invention has a lead 1 for mounting the semiconductor element 5 on one surface of the insulating film 2, and the surface of the lead 1 is made of a metal having poor wettability to solder. The lower layer 3 and the metal upper layer 4 having good wettability are formed. The metal upper layer 4 on the leads outside the semiconductor element 5 mounting portion is partially removed in order to prevent the solder used for connecting to the circuit wiring on the external substrate from flowing into the film carrier of the present invention. Thus, a region A exposing the metal lower layer 3 is provided.

In FIG. 1, the insulating film 2 used in the film carrier of the present invention has electrical insulating properties, and its material is not limited as long as it has appropriate flexibility.
For example, polyester resin, epoxy resin, urethane resin, polystyrene resin, polyethylene resin, polyamide resin, polyimide resin, ABS resin, polycarbonate resin, silicone resin, fluororesin, etc. thermosetting resin or thermoplastic resin. It can be used regardless of. Of these, it is preferable to use a film made of a polyimide resin from the viewpoint of heat resistance and mechanical strength.
The thickness of the insulating film 2 is usually preferably about 5 to 150 μm.

The lead 1 formed on one surface of the insulating film 2 is preferably made of a conductive material such as various metals such as gold, silver, nickel and cobalt, and various alloys containing these as main components. The semiconductor device 1 is placed on the leads 1 and electrically connected thereto.

First, a metal lower layer 3 made of nickel, chromium or the like having poor wettability with respect to solder is formed on the surface of the lead 1 by a method such as plating. Then, a metal upper layer 4 made of gold, silver, tin, lead, solder or the like having good wettability with respect to solder is formed thereon by a method such as plating. The thickness of the metal lower layer 3 and the metal upper layer 4 is usually 1
To about 50 μm and 0.1 to 10 μm,
It is preferable from the viewpoint of easy formation of the area A described later.

In the present invention, in order to prevent the inflow of solder, a metal having poor wettability with respect to the solder and a metal having good wettability are used, but the surface tension of each metal is used as an index of wettability. You can That is, the surface tension of the lower metal layer 3 is larger than that of the upper metal layer 4, and specifically, Acta Met., 4 , 576 (1956) and Chem. Rev., 52 , 4
17 (1953), Z.anorg. Und Allge. Chem., 276 , 227 (195
Surface tension (γ _S ) measured by the method described in 4)
Is preferably 3000 dynes / centimeter or more for the metal lower layer 3.

In the present invention, as shown in FIG. 1, the lead 1 having the metal layers laminated on the surface as described above is provided with an area A in which the metal lower layer 3 is exposed in order to prevent the inflow of solder. To do. Examples of the forming method include a mechanical processing method such as cutting and polishing, a chemical etching method for selectively dissolving an upper metal layer, and a dry etching method by laser irradiation or light irradiation. Among these methods, in order to fabricate a film carrier in which the inner lead bonding portion and the outer lead bonding portion are brought close to each other, the semiconductor elements are mounted at high density, and the region A is formed with high accuracy,
It is preferable to adopt a dry etching method by irradiation with an ultraviolet light laser. When the region A is formed by using an ultraviolet laser, for example, nickel is formed on the metal lower layer 3 and gold is formed on the metal upper layer 4, and the irradiation energy of the ultraviolet laser is set to an energy value capable of selectively removing only gold. Then, by irradiating the laser, only the upper metal layer 4 can be removed to form the region A where the lower metal layer 3 is exposed.

The size of the area A formed on the film carrier of the present invention may be such that the solder used for connection with the external substrate does not flow in, and is preferably 10 to 50.
It is formed on the surface of the lead 1 with a width of about 0 μm.

FIG. 2 is an enlarged perspective view of only one lead of the film carrier of the present invention. In order to prevent the solder from flowing into the lead 1, a region A is formed in which the metal upper layer 4 around a part of the lead is selectively removed to expose the metal lower layer 3.

FIG. 3 is a partial cross-sectional view of the semiconductor device of the present invention in which the semiconductor element 5 is placed and connected to the film carrier of the present invention and is connected to the circuit wiring 7 on the external substrate 6 by the solder 8. By using the film carrier of the present invention, the solder 8 used when connecting to the external substrate 6
Is blocked by the formation of region A as shown.

[0017]

As described above, by using the film carrier of the present invention, when a semiconductor element is mounted and connected to an external substrate to form a semiconductor device, the solder used when connecting to the external substrate is semiconductor element connection. The effect that the electric connection reliability is extremely improved without flowing into the part.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a state in which a semiconductor element is placed and connected using the film carrier of the present invention.

FIG. 2 is an enlarged perspective view of only the lead portion of the film carrier of the present invention.

FIG. 3 is a partial cross-sectional view of a semiconductor device of the present invention.

[Explanation of symbols]

 1 Lead 2 Insulating Film 3 Metal Lower Layer 4 Metal Upper Layer 5 Semiconductor Element 6 External Board 7 Circuit Wiring 8 Solder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Hino 1-2-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Inventor Mikio Aizawa 1-21-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (3)

[Claims] 1. A film carrier having a semiconductor element mounting lead on one surface of an insulating film, wherein a metal lower layer having poor wettability to solder and a metal upper layer having good wettability are successively formed on the surface of the lead. A film carrier, wherein a metal upper layer is formed and a metal upper layer on a lead surface in a region outside a semiconductor element mounting portion is partially removed to expose a metal lower layer. 2. A semiconductor device in which a semiconductor element is placed on and connected to the film carrier according to claim 1. 3. A semiconductor device in which a semiconductor element is placed and connected to the film carrier according to claim 1 and is connected to a circuit wiring on an external substrate.