JPH06216199A - Manufacture for film carrier - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a film carrier which can supply especially the film carrier having a long service life in regard to the manufacture of the film carrier having inner leads which are connected to the electrodes of a semiconductor chip. CONSTITUTION:A film carrier includes inner leads 12 formed by depositing a tin or lead-containing tin plating film 12b on the surface of inner lead bodies 12a, and, after the generation of granular projections on the surface of the plating film 12b and prior to the generation of whiskers, heat treatment is performed to release internal strain existing in this plating film 12b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a film carrier having inner leads connected to electrodes of a semiconductor chip, and more particularly to a method of manufacturing a film carrier having a long shelf life.

[0002]

2. Description of the Related Art Next, a conventional method for manufacturing a film carrier will be described with reference to FIGS.

FIG. 2 is an explanatory view of a film carrier manufactured by a conventional manufacturing method. FIG. 2 (a) is a plan view of a main part, and FIGS. 2 (b) and 2 (c) are main part sides. FIG. Further, FIG. 3 is an explanatory diagram of the granular protrusions and whiskers, and FIGS. 3A to 3D are enlarged side sectional views of main parts schematically showing the generation process of the granular protrusions and whiskers. .

In this specification, the same parts and the same materials are allotted with the same reference numerals throughout the drawings. In the conventional method of manufacturing a film carrier,
As shown in FIGS. 2 (a) and 2 (b), a copper foil 12 'adhered to an insulating tape 11 such as a polyester tape is etched, and a comb shape protruding like a cantilever into the device hole 11a of the insulating tape 11 is etched. After forming the inner lead body 12a, a tin plating film 12b containing tin or lead (hereinafter simply referred to as a plating film 12b) is formed on the surface of the inner lead body 12a by 0.5 to 0.5
The inner lead 12 was formed by depositing with a thickness of about 1 μm.

The tip of the inner lead 12 of the film carrier is connected to the bump electrode 21a of the semiconductor chip 21.
To bond to the bump electrode 21 as shown in Fig. 2 (c).
After the tip of the inner lead 12 is overlaid on a, use the bonding tool 22 heated to a specified temperature to
When the tip of the inner electrode 12 is pressed, the plating film 12b is melted and the bump electrode 21a and the tip of the inner lead 12 are joined.

[0006]

By the way, in the film carrier manufactured by the conventional film carrier manufacturing method, whisker-shaped whiskers 14 are generated from the plating film 12b (see FIGS. 3 (c) and 3 (d)). 2) and diffusion of copper atoms from the inner lead body 12a to the plating film 12b.

The whiskers 14 often grow under the internal strain existing in the plating film 12b as an energy source and are exposed to a dangerous state of short-circuiting the inner leads 12 adjacent to each other.

Therefore, in the conventional manufacturing method,
Immediately after the production, heat treatment is performed at a temperature of about 100 ° C. for about 1 hour to release the internal strain of the plated film 12b and prevent the whiskers 14 from being generated.

However, the diffusion of copper atoms into the plating film 12b raises the melting point of the plating film 12b and changes the bonding conditions between the tip portion of the inner lead 12 and the bump electrode 21a.

Therefore, in the film carrier manufactured by the conventional manufacturing method, the inner lead
The period during which the 12 and the bump electrode 21a can be stably bonded, that is, the usable period of the film carrier is set, and in principle, the period beyond this usable period is not used.

The present invention has been made to solve the above problems, and an object thereof is to provide a method of manufacturing a film carrier having a long usable period.

[0012]

[Means for Solving the Problems] The object is to provide a tin plating film 12b containing tin or lead on the surface of the inner lead body 12a.
In the method of manufacturing a film carrier including the inner lead 12 formed by depositing, after the generation of the granular protrusions 13 from the surface of the plating film 12b and before the generation of the whiskers 14,
This is achieved by a method of manufacturing a film carrier, which is characterized in that it is subjected to a heat treatment for releasing the internal strain existing in the plating film 12b.

[0013]

The whiskers 14 described with reference to FIG. 3 do not occur immediately from the plating film 12b having internal strain, but after the granular projections 13 made of tin or tin containing lead are generated in the plating film 12b. , Are generated from the granular projections 13.

Therefore, if the heat treatment for eliminating the internal strain existing in the plating film 12b, for example, the heat treatment of 100 ° C. for 1 hour is performed after the generation of the particle protrusions 13 in the plating film 12b, the whiskers from the particle protrusions 13 can be obtained. Since the generation of 14 is prevented, the adjacent inner leads 12 are not short-circuited by the whiskers 14.

On the other hand, the granular projections 13 which are tin or a lump of tin containing lead project in a direction away from the surface of the inner lead body 12a. Therefore, in the film carrier manufactured by the method for manufacturing a film carrier of the present invention as compared with the film carrier manufactured by the conventional method for manufacturing a film carrier, the inner lead body is
The diffusion time of copper atoms from 12a to the granular projections 13 becomes long, and the expiration date becomes long.

[0016]

EXAMPLES A method of manufacturing a film carrier according to an example of the present invention will be described below with reference to FIGS.

FIG. 1 is an explanatory view of a film carrier according to a manufacturing method of an embodiment of the present invention. FIG. 1 (a) is a plan view of a main part and FIG. 1 (b) is a side sectional view of the main part. The manufacturing method of one embodiment of the present invention shown in FIG. 1 is a method in which a film carrier manufactured by the conventional method for manufacturing a film carrier described with reference to FIG. 100 in an oxidizing atmosphere, such as a nitrogen atmosphere
The heat treatment is performed at a temperature C of about 1 hour.

By such heat treatment, the plating film 12b of the inner lead manufactured by the manufacturing method of the embodiment of the present invention is fixed in the state shown in FIG. 3 (b).
The whiskers 14 as shown in (d) do not grow from the plating film 12b.

Since the internal strain of the plated film 12b fluctuates considerably depending on the manufacturing lot, the surface of the plated film 12b is observed with a microscope about once a day, and the particle size of the granular protrusions 13 is 2 to 3 μm.
It is certain that the above heat treatment is performed after confirming that the growth has reached about m.

The film carrier manufactured by the manufacturing method according to the embodiment of the present invention has inner leads 12
The whisker 14 does not occur from the plating film 12b and the diffusion of copper atoms from the inner lead body 12a to the granular protrusions 13 takes a long time, so that the usable period is long, for example, when stored at room temperature. It will be about 3 months.

[0021]

As described above, the present invention makes it possible to provide a method of manufacturing a film carrier having a long usable period.

[Brief description of drawings]

FIG. 1 is an explanatory view of a film carrier according to a manufacturing method of an embodiment of the present invention.

FIG. 2 is an explanatory view of a film carrier manufactured by a conventional manufacturing method.

FIG. 3 is an explanatory diagram of a granular protrusion and a whisker.

[Explanation of symbols]

 11, polyester tape 11a, device hole 12, inner lead 12a, inner lead body 12b, plating film 13, granular protrusions 14, whiskers 21, semiconductor chip 21a, bump electrodes 22, bonding tools

Claims (1)

[Claims] 1. A method of manufacturing a film carrier comprising an inner lead (12) formed by depositing a tin plating film (12b) containing tin or lead on the surface of an inner lead body (12a), Characterized by being subjected to heat treatment to release the internal strain existing in the plating film (12b) after the generation of the granular protrusions (13) and before the generation of the whiskers (14) from the surface of the plating film (12b). And a method for manufacturing a film carrier.