JPH0260228B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a bumped film carrier used for connecting a semiconductor element to a lead frame or an external substrate.

(Prior art) Film is generally used to connect semiconductor elements and lead frames or external substrates because it allows multiple electrodes to be bonded at once, is fast, mass-producible, and has high reliability. Carrier method is used.

Among these film carrier methods, especially the bumped film carrier method, as shown in FIG. This is a method of connecting by thermocompression bonding.

Conventionally, as a method for manufacturing a bumped film carrier, a bumped film carrier is manufactured by thermally transferring gold bumps formed separately by a gold plating method to the tips of the fingers of an ordinary film carrier without bumps; A method in which bumps are formed at the tip of the finger by etching stepwise using thicker copper foil than usual. From a substrate made of a laminate of polyimide resin 3 and copper foil 10, holes 5 are formed in the polyimide resin by etching. 4th by plating from inside the hole
As shown in the figure, there is a method (Japanese Unexamined Patent Publication No. 55-48954) in which the bumps 4 are made to protrude and then a copper foil is formed on the wiring pattern 2 to produce the bumped film carrier 1.

(Problems to be solved by the invention) The conventional method for manufacturing a film carrier with bumps is as follows:
However, there is a problem in that it is difficult to cope with the increase in the number of pins, that is, the increase in density, which is most expected for film carriers.

For example, in the method of forming bumps by transfer,
Since it is necessary to downsize the transfer bump, there are problems in controlling the size of the transfer bump and in positioning the bump to the finger during thermal transfer. Furthermore, in the method of forming bumps by etching, the etching technique is limited because thick copper foil is used. Furthermore, in the method of protruding the bump by plating,
There is a problem in that it is difficult to control the height and diameter of the bump by plating.

The present invention has been made based on the above-mentioned background, and its purpose is to manufacture a film carrier with bumps that can respond to the increased number of pins, that is, higher density, which is required for film carriers. It is to provide law.

(Means and Effects for Solving the Problems) According to the present invention, the method for manufacturing a film carrier with bumps includes etching a laminate of an etchable resin film and a conductive layer to form a predetermined pattern on the resin layer. forming an aperture (provided that the bottom of the aperture is in contact with the conductive layer), and then applying a conductive material inside the aperture, preferably by electroplating,
Fill the conductive layer with electroless plating, applying a conductive paste, or a combination to form a conductor that is electrically connected to the conductive layer, and remove the resin from at least the resin surface near the conductor by etching to form the conductor. This consists of protruding as a bump.

This invention will be explained in more detail below.

In the manufacturing method of this invention, a laminate of an etchable resin film and a conductive layer is etched.

Etchable resins include resins that can be etched with a film etching solution, such as polyimide resins, polyamide resins, polyamide resins, and polyetherimide resins. Examples of the material of the conductive layer include copper, silver, nickel,
tin, iron, cobalt, aluminum, gold, platinum,
metals such as, and their alloys.

The laminate according to the present invention can be prepared by forming a layer of conductive material on a resin film by chemical plating, vapor deposition, sputtering, etc., and further applying a thick layer of copper or the like as necessary. Can be done. In addition, this laminate is produced by coating a resin film with an etching adhesive, and after drying, laminating a metal foil such as copper, bonding with heat, and curing the adhesive by heating in an oven. Can be done. Furthermore, the laminate may be prepared by coextruding the resin material with the metal foil. Note that when an adhesive is used, it is desirable that the adhesive also be etched. Examples of the adhesive include polyimide adhesives, polyamide adhesives, polyamide adhesives, and polyetherimide adhesives.

Before etching the resin of the laminate, if necessary, the conductive layer of the laminate can be formed into a conductive layer with a wiring pattern by a wiring pattern forming method such as an etching method or an additive method. The wiring pattern can also be formed after etching the hole or forming the bump conductor.

To form predetermined openings in the resin layer, a photosensitive resist that is resistant to film etching liquid is applied to the film side using, for example, a roll coater, and this coated surface is exposed to light, followed by development and etching followed by normal etching. This is done through manipulation. In this invention, conventional reagents and materials can be used for the etching operation.

The diameter, size, position, spacing, etc. of the apertures can be determined according to the specifications of the film carrier. However, the bottom of this opening needs to be at least in contact with the back surface of the conductive layer.

In this invention, the openings are then filled with a conductive material to form a conductor electrically connected to the conductive layer.

Filling with the conductive material can be carried out, for example, by electroplating, electroless plating, or by applying a conductive paste. Any conductive material may be used as long as it does not contradict the purpose of the present invention, and examples thereof include copper, nickel, iron, aluminum, lead, zinc, gold, silver, platinum, and graphite. During this filling, it is desirable to prevent the conductive material from coming out of the opening. This is because the resulting conductor is formed using the apertures as a mold, and the dimensions and shape of the conductor are to be controlled by the apertures.

If desired, the exposed surface of the conductor may be coated with nickel underplating and gold plating to provide a surface suitable for bonding to an aluminum pad of a semiconductor device.

Since the bottom of the opening is in contact with the back surface of the conductive layer, the resulting conductor is electrically connected to the conductive layer.

Next, the resin is removed by etching from at least the resin surface near the conductor, and the conductor is made to protrude as a bump. That is, the resin film is thinned by etching the whole or partial surface of the resin film to a required thickness, and the conductor is made to protrude from the resin surface as a bump.

Etching of only a necessary area is carried out according to the usual etching operations of coating, exposing, developing and etching a photosensitive resist. In the case of etching a partial surface, the resin layer in that portion may not only be made thinner, but also the entire resin may be removed in the thickness direction.

If necessary, after the bump formation, the conductive layer of the laminate is patterned into a wiring pattern by conventional etching operations such as coating, developing and etching a photosensitive resist, or by a so-called add-a-day method. The present invention will be specifically explained with reference to examples of drawings.

First, a laminate of an etched resin film 3 and a conductive layer 10 as shown in FIG. 1a is prepared. The resin layer 3 of this laminate is etched to form an opening 5 in the resin layer 3 (FIG. 1b). Note that the bottom of this opening 5 is assumed to be in contact with the back surface of the conductive layer 10. Next, a conductor 6 is filled in the opening 5 with a conductive material and electrically connected to the conductive layer 10.
(Fig. 1c). The resin layer 3 is thinned by etching, and the conductor 6 is attached to the bump 4 from the resin surface.
(Fig. 1d). In the example shown in FIG. 1, after the bumps are formed, the conductive layer 10 is formed into a wiring pattern, and the conductive layer 10 in contact with the bumps is formed on the finger 2, as shown in FIG. 1e.

The present invention is not limited to the example shown in FIG. 1, but can be applied to a bumped film carrier having normal device holes by removing all the resin near the conductor 6 in the thickness direction as shown in FIG. 2a. . Also, the second
As shown in FIG. b, the resin can be thinned by removing the resin from a partial surface in the thickness direction.

(Example) The present invention will be explained below using specific examples.

50 μm thick polyimide film (manufactured by Dupont)
A conductive layer of copper with a thickness of 18 μm was formed on one side of the glass by chemical plating and electroplating.

An alkali-resistant photoresist was applied to the film side, exposed and developed, and etched with a film etching solution to form holes with a diameter of 80 μm.

The inside of this hole was filled with copper by electroplating to form a conductor. The outermost surface of this conductor was surface-treated with nickel underplating and gold plating.

Next, the film surface on which bumps are to be formed is etched with a film etching solution, and the film thickness is reduced to 30 μm.
At the same time, bumps with a height of 20 μm were made to protrude.

The conductive layer was then etched to form a wiring pattern to produce a bumped film carrier.

〔Effect of the invention〕

The following effects can be obtained by this invention.

(a) The size of the bump corresponds to the size of the aperture made in the film, and the size of the aperture can be easily controlled by etching, so the size of the bump can be controlled.

In other words, the conventional bump formation method
48954), since the bumps are formed by rising from the film surface, the bumps grow at the same rate not only in the height direction but also in the lateral direction, making it difficult to form small bumps. However, in this invention, since the dimensions of the bump can be controlled, small bumps can be formed.

Therefore, there is less risk of contact with adjacent bumps, and the pitch of the bumps can be made extremely narrow, making it possible to accommodate semiconductor devices with many pins.

(b) Thin the film by etching. By knowing the etching speed of the film,
The degree of thinning of the film can be controlled,
Not only the size of the bump but also the height of the bump can be easily determined.

(c) In this invention, since leads corresponding to the fingers of the film carrier are formed on the film, defects such as breakage and bending of the fingers during the process, which are often seen in film carriers having device holes, are reduced. can do. Furthermore, since the thinned resin layer reinforces the bumps, damage to the bumps can be prevented.

(d) Furthermore, since the bumps can be formed from expensive metals other than gold, there is no need for thick gold plating as in the past, and semiconductor elements can be bonded with a thin plating layer.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view for explaining each step of the method of the present invention, FIG. 2 is a cross-sectional view of a film carrier showing a modification of FIG. 1, and FIG. FIG. 4 is a cross-sectional view showing the steps of a conventional method for manufacturing a film carrier with bumps. 1...Film carrier, 2...Finger, 3
... Resin, 4 ... Bump, 5 ... Hole, 6 ... Conductor, 7 ... Semiconductor, 8 ... Aluminum pad, 10 ...
...conductive layer.

Claims (1)

[Claims] 1. A laminate of an etchingable resin film and a conductive layer is etched to form a predetermined opening in the resin layer (provided that the bottom of the opening is in contact with the conductive layer). ), and then filling the opening with a conductive material to form a conductor electrically connected to the conductive layer, and removing the resin from at least the resin surface near the conductor by etching to form the conductor. A method for producing a bumped film carrier, the method comprising protruding as a bump. 2. The manufacturing method according to claim 1, wherein the conductive material is filled into the opening by electroplating, electroless plating, applying a conductive paste, or a combination thereof.