JPH0831499B2 - Film carrier for semiconductor device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a film carrier for a semiconductor device, more specifically, a film carrier system (Tape Automated Bonding (hereinafter referred to as “Tape Automated Bonding”) in which semiconductor elements are continuously incorporated into the film carrier by wireless bonding. (Hereinafter abbreviated as TAB)) and a manufacturing method thereof.

<Prior Art> In the mounting technology of semiconductor elements, automation has been attempted in order to mass-produce products having performances above a certain level at high speed.

One of those developed for the purpose of this automation is the TAB that continuously incorporates semiconductor elements into a long film carrier by wireless bonding.

In this TAB, the corresponding inner leads of the film carrier are thermocompression-bonded by the bonding tool to each electrode terminal of the semiconductor element 5 via the bumps, and then the insulating fluid resin is botted and sealed. The operation of being applied is continuously performed.

Then, the film carrier in which the semiconductor element is potted and sealed is cut at a predetermined position, and the outer leads thereof are soldered to the printed board to form a semiconductor device.

The film carrier used for such TAB is usually formed by punching out necessary through holes such as device holes and sprocket holes in a flexible insulating film such as polyimide resin or polyester resin, and pasting copper foil on the film. And then photoetching the copper foil,
It is formed on a lead of a desired copper foil pattern. First
As shown in FIG. 11, this copper foil is coated with a plating layer of 0.5 to 1.0 .mu.m thick solder, tin or the like on both surfaces thereof in order to obtain desired bonding characteristics of a semiconductor element or to prevent rust. If necessary, the inner lead 31 of the copper foil
The outer lead 32 may be plated with solder, tin or the like, and the outer lead 32 may be plated with precious metal such as gold, silver or platinum.

By the way, in recent years, the number of leads 3 of the film carrier has tended to increase due to the improvement in the degree of integration of semiconductor devices. Therefore, in order to manufacture a semiconductor device having the same shape and size as the conventional one, it is desired to develop a so-called fine pitch TAB film carrier in which the pitch of the inner leads 31 is made smaller.

However, the following problems have been encountered in the production of a fine pitch TAB film carrier, particularly in the production of a film carrier having an inner lead pitch of 100 μm or less.

Since the thickness of the copper foil forming the leads is as thick as 35 μm, if the width of the inner leads and the gap between them are set to 50 μm or less, pattern loss or short circuit may occur during pattern etching of the inner leads.

In other words, the width of the lead and the space between the leads are about
If it is 130% or less, the resist ink is partially peeled off by the time the etching progresses in the depth (thickness) direction, and lead pattern defects occur. When etching is stopped,
Incomplete etching causes shorts between the leads.

Therefore, a copper foil is adhered to the film in which the sprocket holes and device holes are formed, and the copper foil is thinned by pickling, or a thin copper foil having a thickness of 15 to 25 μm is used in advance to reduce the thickness. Attempts have been made to form leads.

However, since the thickness of the copper foil is reduced by such a method, the mechanical strength is lowered, and the copper foil is dropped into the device hole. The portion exposed by the photomask mounted on the portion is out of focus, and an accurate photoresist is not formed. Consequently, it is impossible to form a fine lead pattern by fine etching.

In etching copper foil, an etching solution is sprayed at a high pressure, but there is nothing to support the copper foil in the device hole on the back side of the film carrier. As a result, the inner leads are deformed, and the reliability of the semiconductor device is reduced.

As described above, the conventional method of manufacturing a film carrier has many obstacles in manufacturing a film carrier for fine pitch TAB.

<Problems to be Solved by the Invention> An object of the present invention is to solve the above-mentioned drawbacks of the prior art,
Fine processing of leads is possible, especially fine pitch TA
It is to provide a method for manufacturing a film carrier for a semiconductor device suitable for manufacturing a film carrier for B and a film carrier for a semiconductor device obtained thereby.

<Means for Solving Problems> Such an object is achieved by the present invention described below.

That is, the present invention, when manufacturing a film carrier for a semiconductor device formed by forming a lead by a conductive film on a flexible insulating film, after forming a lead of a desired pattern on the flexible insulating film, A method for manufacturing a film carrier for a semiconductor device, which comprises forming a device hole and / or an outer lead bonding hole in a flexible insulating film.

The lead is preferably formed by attaching a copper foil or forming a conductor film on the flexible insulating film by plating and then etching the conductor film.

Further, it is preferable that the lead is formed by forming a mask having a desired pattern on the flexible insulating film and plating a portion not covered with the mask.

The device hole and / or the outer lead bonding hole is preferably formed by an ion milling method.

Further, the formation of the device hole and / or the outer lead bonding hole is preferably performed by a chemical etching method.

Further, the present invention provides a film carrier for a semiconductor device manufactured by any one of the above manufacturing methods, wherein the conductor film has a thickness of 30 μm or less.

The average width of each inner lead is preferably 20 to 50 μm.

And the average pitch of adjacent inner leads is 100μ
It is preferably m or less.

The method of manufacturing a film carrier for a semiconductor device of the present invention is fundamentally different from a method of forming a lead after forming a through hole such as a device hole in a base film like the conventional method of manufacturing a film carrier. Things
A lead having a desired pattern is formed on a base film on which device holes and the like are not formed, and then device holes and the like are formed.

The lead is formed around the device hole opened in the base film of the film carrier, and since the inner lead thereof projects into the device hole, the lead needs a certain mechanical strength. Although it is not possible to reduce the thickness of the conductor film forming the leads (thickness of 30 μm or less), in the present invention, since the leads are formed on the base film having no device hole, the conductive film forming the leads is The thickness of the conductor film can be reduced (thickness of 30 μm or less) without being restricted by the thickness, and thus fine processing of leads by etching becomes possible.

Hereinafter, a film carrier for a semiconductor device and a method for manufacturing the same of the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.

1 to 5 are cross-sectional views showing the steps of the method for producing a film carrier of the present invention. Hereinafter, each step will be described with reference to these drawings.

<1-a> Sprocket holes 6, 6 are formed on both sides of the base film (flexible insulating film) 2 of the film carrier 1 by, for example, press punching, and then the first
As shown in the figure, the conductor film 8 is laminated on the base film 2 at a position between the sprocket holes 6 on both sides.

The conductor film 8 is laminated by applying an adhesive on the base film 2 and attaching a metal foil such as a copper foil, or by plating (preferably vapor deposition) a desired metal on the base film 2. , A method of forming a metal layer, and the like.
Here, the plating means normal electrolytic plating, electroless plating, immersion plating, wet plating such as spray plating,
Or evaporation, sputtering, ion plating,
It means dry plating such as CVD. In this specification, these are collectively referred to as “plating”.

As the constituent material of the conductor film 8, copper, iron, nickel, chromium, aluminum or the like or an alloy containing these (for example, Cu—Ni alloy, Cu—Zn alloy, Cu—Ni—Zn alloy, Cu—Sn) is used.
Alloy, Cu-Zr alloy, 42% Ni-Fe alloy, SUS430) and the like.

Although the thickness of the conductor film 8 depends on its constituent material, it is usually
It is preferably 30 μm or less, particularly about 5 to 25 μm. This is because if the thickness is less than 5 μm, the strength becomes insufficient when processed into leads, and if it exceeds 25 μm, particularly 30 μm, fine processing of the leads becomes difficult.

When the thickness of the conductor film 8 is equal to the thickness of the final lead, the thickness of the conductor film is preferably within the above range,
For example, it is possible to adhere a copper foil having a thickness of more than 25 μm onto the base film 2 and then subject the copper foil to pickling to reduce the thickness to the above range.

Further, the constituent material of the flexible film forming the base film 2 is preferably a high heat resistant resin such as polyimide or polyamide imide. The reason is that the temperature is 400 to 500 ° C when soldering with semiconductor elements or resin sealing.
Therefore, it is required that the base film is not melted or thermally deformed even at such a high temperature.

<2-a> As shown in FIG. 2, a resist layer 7 having a predetermined pattern (positive type) is formed on the conductor film 8.

The method of forming the resist layer 7 is not particularly limited, and a generally used photoresist method or screen printing method may be used.

<3-a> As shown in FIG. 3, the conductor film 8 is etched using the resist layer 7 as a mask, and then the resist layer 7 is peeled and removed to form the leads 3 having a desired pattern as shown in FIG. obtain. The thickness of each lead 3 thus obtained is preferably about 5 to 25 μm for the reason described above.

In the present invention, since the leads 3 are formed on the base film in which the device holes 4 and the outer lead bonding holes 5 have not been formed yet, it is possible to process the leads without consideration of securing the strength of the leads. it can. As a result, the conductor film 8 forming the lead 3
Can be thinned, and fine processing of leads can be easily performed. For example, in a copper foil lead having a thickness of about 5 to 25 μm, the average width of each inner lead can be set to 20 to 50 mm or less, and / or the average pitch of adjacent inner leads can be set to 100 μm or less.

<4-a> As shown in FIG. 5, a device hole 4 and an outer lead bonding hole 5 are formed at predetermined positions of the base film 2 on which the leads 3 are formed to obtain the film carrier 1 of the present invention.

The device hole 4 and the outer lead bonding hole 5 are formed by an ion milling method or a chemical etching method. These will be described below.

The ion milling method is a method of physically processing an object to be processed by the kinetic energy of the ion beam. The principle is that the ion beam traveling straight from the ion source toward the object (base film) is to be processed. This is to collide with the portion other than the portion covered with the resist (the portion forming the device hole 4 and the outer lead bonding hole 5) and cut the portion.

This ion milling method has a feature that high-precision processing is possible.

Regarding the ion milling method, Hitachi Review VOL.68
No. 6 (1986-6), p49-52, "Development of large-diameter ion beam milling apparatus".

The chemical etching method is an etching method that utilizes that polyimide (base film) is dissolved in an aqueous solution of hydrazine, and has an advantage that the base film can be easily etched by chemical treatment.

Next, a method of manufacturing a film carrier having a lead forming method different from that described above will be described with reference to FIGS.

<1-b> Sprocket holes 6 are formed on both sides of the base film (flexible insulating film) 2 of the film carrier 1 by, for example, press punching, and then on the base film 2 as shown in FIG. Photoresist 9 is applied.

<2-b> The photoresist 9 is exposed and developed to form a resist layer 9 having a predetermined pattern (negative type) as shown in FIG.

<3-b> As shown in FIG. 8, partial plating (preferably vapor deposition) is performed using the resist layer 9 as a mask,
The conductor film 8 is formed. The constituent material and thickness of the conductor film 8 are the same as described above.

Such a method of forming leads by plating is
There is an advantage that a finer pattern can be easily obtained as compared with the method of attaching the metal foil and etching the same.

Further, the composition and film thickness of the plating metal, that is, the constituent metal of the lead can be easily selected, and it is particularly advantageous in the case of a binary or ternary or higher alloy.

<4-b> The resist layer 9 is peeled off and removed to obtain leads 3 having a desired pattern as shown in FIG.

<5-b> As shown in FIG. 10, device holes 4 and outer lead bonding holes 5 are formed at predetermined positions of the base film 2 in the same manner as in <4-a>, and the film carrier 1 of the present invention is obtained. obtain.

<Examples> Specific examples of the present invention will be described below.

Example 1 (1-1) As a base film, thickness 75 μm, width 35 mm
The sprocket holes having a predetermined pitch were continuously formed on both sides of the polyimide long film of No. 1 by press punching.

(1-2) An epoxy adhesive was applied to the lead forming surface of this base film in a thickness of 20 μm, and a rolled copper foil having a thickness of 18 μm and a width of 26.4 mm was attached.

(1-3) Next, a photoresist ink was uniformly applied to the surface of the copper foil by a roll coater method, and this was exposed (baked) and developed to form a desired positive photoresist pattern.

(1-4) Next, the copper foil was etched with an etching solution (cupric chloride solution), and the photoresist was removed with a stripping solution (10% NaOH solution) to form leads of a desired pattern. The lead pattern has an inner lead width of 30μ.
m, the gap between adjacent inner leads was 30 μm, that is, the pitch was 60 μm.

(1-5) Next, by a ion milling method, a 5.7 × 6.3 mm square device hole was formed in the center of the base film in the width direction, and a width of 3.0 mm and a length of 1 were formed on the periphery of each side of the device hole.
An outer lead bonding hole of 8.0 mm was formed to obtain a film carrier shown in FIG.

The ion milling was performed using the ion milling device manufactured by Hitachi, Ltd. under the following conditions.

An Ar ion source is used as the ion source, and the beam current density is 0.5 m.
A / Cm ² was used to mask and process parts other than the cut part with a stainless steel mask. Milling speed is 1 μm / min
That is, the speed was much higher than that of metal milling.

[Example 2] (2-1) Same as (1-1) above (2-2) 99.99% copper was vapor-deposited on the lead formation surface of the base film to form a copper layer having a thickness of 10 µm.

(2-3) Above (1-3), (1-4) and (1-
Same as 5) [Example 3] (3-1) Same as (1-1) above except that a long glass epoxy film was used as the base film.

(3-2) Same as (2-2) and (2-3) above [Example 4] (4-1) Same as (1-1) above (4-2) Photo on lead formation surface of base film A resist ink was uniformly applied, and this was exposed (baked) and developed to form a desired negative photoresist pattern.

(4-3) With this photoresist as a mask, 99.99
% Copper was partially vapor-deposited to form a copper layer having a thickness of 5 μm.

(4-4) The photoresist was removed with a stripping solution (10% NaOH solution) to form leads with a desired pattern. The lead pattern is the same as in (1-4) above.

(4-5) Same as (1-5) above (Example 5) (5-1) Same as (1-1), (1-2), (1-3) and (1-4) above ( 5-2) The above (1-5) according to the chemical etching method.
Device holes and outer lead bonding holes similar to those described above were formed.

At the time of chemical etching, an epoxy-based solder resist ink was printed by a screen printing method for masking.

The etching liquid used was a 10% hydrazine aqueous solution, pH 10.5, and a liquid temperature of 80 ° C.

When the lead portions of the film carriers obtained in Examples 1 to 5 above were examined, it was confirmed that fine pitch lead patterns could be formed with high accuracy without pattern defects, short circuits and lead deformation.

<Effects of the Invention> According to the film carrier for a semiconductor device and the method for manufacturing the same of the present invention, after forming leads of a desired pattern on the flexible insulating film, device holes and / or outer lead bonding holes are formed in the film. By forming the leads, the leads can be formed without being restricted by the forming method and the film thickness of the conductor film forming the leads, and therefore, the fine pattern can be easily processed.

As a result, for example, it has become possible to manufacture a fine pitch TAB film carrier having a pitch between leads of 100 μm or less.

[Brief description of drawings]

1 to 5 are cross-sectional views showing an example of steps of a method for manufacturing a film carrier for a semiconductor device according to the present invention. 6 to 10 are cross-sectional views showing another example of steps of the film carrier for a semiconductor device of the present invention. FIG. 11 is a plan view of the film carrier for a semiconductor device of the present invention. DESCRIPTION OF SYMBOLS 1 ... Film carrier, 2 ... Base film, 3 ... Lead, 31 ... Inner lead, 32 ... Outer lead, 4 ... Device hole, 5 ... Outer lead bonding hole, 6 ... Sprocket Hole, 7 ... resist layer, 8 ... conductor film, 9 ... photoresist (resist layer)

Claims (6)

[Claims] 1. When manufacturing a film carrier for a semiconductor device in which leads are formed of a conductive film on a flexible insulating film, the leads of a desired pattern are formed on the flexible insulating film, and then the flexible insulating film is formed. A method of manufacturing a film carrier for a semiconductor device, comprising forming a device hole and / or an outer lead bonding hole in a flexible insulating film. 2. The semiconductor according to claim 1, wherein the lead is formed by forming a conductor film on the flexible insulating film by pasting or plating a copper foil, and then etching the conductor film. Method of manufacturing film carrier for device. 3. The lead is formed by forming a mask having a desired pattern on the flexible insulating film and plating a portion not covered with the mask.
A method for manufacturing a film carrier for a semiconductor device according to. 4. The method of manufacturing a film carrier for a semiconductor device according to claim 1, wherein the device hole and / or the outer lead bonding hole is formed by an ion milling method. 5. The method of manufacturing a film carrier for a semiconductor device according to claim 1, wherein the device hole and / or the outer lead bonding hole is formed by a chemical etching method. 6. A film carrier for a semiconductor device manufactured by the method for manufacturing a film carrier for a semiconductor device according to claim 1, wherein the conductor film has a thickness of 30 μm or less. Film carrier.