JPH03116847A - Manufacture of film substrate - Google Patents

Abstract

PURPOSE:To form directly wiring leads on a base film without using a bonding agent by a method wherein a device hole formed in the base film is blocked with a sheet, on which an etching can be performed, a plating is applied on the base film and the sheet to form the wiring leads and the sheet, with which the device hole is blocked, is removed. CONSTITUTION:A device hole 2 is formed in a base film 1 and thereafter, a dry sheet 3 is laminated. When the sheet 3 is exposed and developed through a photomask, the hole 2 is blocked with the sheet 3. After this, after a plated layer 5 is formed on the surface of a metal thin film 4, which is applied on both surfaces of the film 1 and the sheet 3, by an electrolytic plating, a photomask 6 is formed in the same form as those of wiring leads 7. After the layer 5 and the film 4 are etched in order using the resist 6 as a mask, the resist 6 and the sheet 3 are removed. An IC chip 8 is bonded on this film substrate and is sealed with a sealing resin 9. Thereby, even if the arrangement of the wiring leads is reduced in a fine pitch, a sufficient adhesive force can be secured.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a film substrate.

[Prior Art] Conventionally, film substrates having a three-layer structure in which a metal foil is bonded to a base film using an adhesive are known. In this type of film substrate, a metal foil is bonded to a base film with an adhesive, and the metal foil is patterned into a predetermined shape using a photolithography method to form wiring leads.

[Problem to be Solved by the Invention 1] However, in the above-mentioned film substrate, when the wiring leads have a fine pitch, the adhesive force for bonding the metal foil is insufficient. In particular, when adhesives are heated when bonding devices such as semiconductor chips, their adhesive strength weakens, causing misalignment of wiring leads, resulting in problems such as uneven pitch and short #5. Furthermore, since adhesives generally have low insulation resistance, when the pitch is made finer, the electrical resistance between the wiring leads becomes insufficient, causing problems in operation.

An object of the present invention is to enable wiring leads to be formed directly on a base film without using an adhesive, and to allow the wiring leads to protrude into device holes in the base film for good bonding of devices such as semiconductor chips. An object of the present invention is to provide a method for manufacturing a film substrate that can be used.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention covers a device hole formed in a base film with an etched sheet, and then plates the base film and the sheet. The method involves forming a pattern of wiring leads having a predetermined shape, and then removing the sheet that blocks the device hole.

[Function] According to the present invention, the wiring leads made of a plating layer are formed on the base film without using an adhesive, so even if the wiring leads have a fine pitch.

Sufficient adhesive strength can be ensured. Therefore, the wiring leads are less likely to be misaligned due to heating during bonding of devices such as semiconductor chips, and uneven pitches, short circuits, etc. can be prevented. Moreover, since no adhesive is used, it is possible to solve operational problems caused by the lack of electrical resistance caused by conventional adhesives. especially.

Since the wiring leads can protrude into the device hole, devices such as semiconductor chips can be connected to TAB (Tap).
Bonding can be performed effectively using an automated bonding method or the like.

[Embodiment] Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 8.

First, as shown in FIG. 1, device holes 2 are formed in a base film l. This base film l is made of resin such as polyimide or polyester, and has a thickness of 50 to 1
It is about 100 JL. The device hole 2 is a vertically penetrating hole into which a device such as an IC chip is inserted, and is formed by mechanical processing such as pressing, but may also be formed by chemical processing such as etching.

Next, as shown in FIG. 2, a dry sheet 3 for etching is laminated on the upper surface of the base film 1. This dry sheet 3 is made of photosensitive polyimide resin and has a thickness of 10 to 30 pt-m8 degrees.

Then, the dry sheet 3 is exposed to light through a photomask (not shown) and developed. Then, as shown in Figure 3,
An unnecessary portion of the dry sheet 3 is removed, and the dry sheet 3 remains in a portion corresponding to the device hole 2 to close the device hole 2.

Thereafter, a thin metal WJ4 such as copper is deposited on the surfaces of the base film 1 and the dry sheet 3 by vapor deposition, sputtering, or the like. This metal thin film 4 serves as a base layer for a plating layer 5 to be described later.

It is formed on the surface of the base film 1 with sufficient bonding strength. Note that, although the metal thin film 4 is preferably made of the same metal as the plating layer 5, it is not limited thereto.

Next, as shown in FIG. 4, a plating layer 5 is formed on the surface of the metal thin film 4 by electrolytic plating to a thickness of about 20 to 40 JLm. This plating layer 5 is a metal thin film 4 which is a base layer.
Thus, the bonding strength is sufficient for the base film l. In this case, this plating layer 5 is the metal thin layer 1 mentioned above.
If it is the same metal material as g14, the bonding strength will be particularly high, but it may be a different metal material.

Thereafter, as shown in FIG. 5, a photoresist 6 is coated on the plating layer 5, exposed and developed to remove unnecessary portions of the photoresist 6, and form the photoresist 6 into a predetermined shape. That is, the pattern is formed in the same shape as the wiring lead 7 described later.

Then, as shown in FIG. 6, the plating layer 5 and the metal thin film 4 are sequentially etched using the patterned photoresist 6 as a mask to remove unnecessary portions. In this case, if the plating layer 5 and the metal thin film 4 are made of the same metal material,
It can be removed by one etching, but if the materials are different, each layer 5.4 may be etched in order. As a result, the wiring lead 7 made of the plating layer 5 and the metal F1 film 4 has a predetermined shape. pattern is formed.

Thereafter, as shown in FIG. 7, the photoresist 6 on the plating layer 5 is removed by etching, and the dry sheet 3 blocking the device hole 2 is also removed by etching. In this case as well, if the photoresist 6 and the dry sheet 3 are made of the same photosensitive material, both can be removed by one etching. As a result, the wiring leads 7 are formed on the base film l, and the wiring leads 7 are formed on the base film l.
A film substrate with the inner lead portion protruding into the device hole 2 is obtained.

Then, as shown in FIG. 8, this film substrate has an I
C chip 8 is pounded by TAB method.
It is fixed by a fixing resin 9. In this case, the IC chip 8 is inserted into the device hole 2 from below the base film 1, and the bump electrodes 10 of the IC chip 8 are made to correspond to each inner lead part of the wiring leads 7, and a thermopressing jig ( (not shown). Then, the inner lead portion of the wiring lead 7 is bent and each bump electrode lO of the IC chip 8 is bent.
Pounded to. At this time, since the plating layer 5 of the wiring board 7 is formed with sufficient bonding force to the base film l by the gold PA thin film 4, the wiring board 7 is not displaced due to heating by the thermopressing jig. Therefore, the pitch of the wiring leads 7 does not become non-uniform, and the IC chip 8 can be bonded very well without causing any contact. It goes without saying that this film substrate can also solve operational problems caused by the lack of electrical resistance caused by conventional adhesives.

Next, a second embodiment will be described with reference to FIGS. 9 to 15. In this case, the same parts as those in the first embodiment described above are given the same reference numerals, and the explanation thereof will be omitted.

First, a device hole 2 is formed in a base film 1 as shown in FIG. 9, and an etched dry sheet 3 is laminated on the upper surface of the base film 1 as shown in FIG. Then, as in the first embodiment described above, by exposing and developing the dry sheet 3 through a photomask, the dry sheet 3 is exposed to the portion corresponding to the device hole 2, as shown in FIG. device hole 2
After this, the base film 12 and the dry sheet 3 are coated with gold Ji!, which will serve as the base layer. 111! I4 is deposited by vapor deposition or sputtering. After that, wiring leads 7 are formed by printing a plating resist 11 on the metal thin film 4.
Provided outside the lead forming area corresponding to the lead forming area.

Next, as shown in Figure 12, metal thin! A plating layer 12 is formed on i4 by electrolytic plating. This plating layer 12
is formed in a lead formation region corresponding to the wiring lead 7 on the metal thin film 4 using the plating resist 11 as a mask.

In this case, the plating layer 12 is formed as thick as the thickness of the metal thin film 4 in anticipation of etching in a later process.

Thereafter, as shown in FIG. 13, the plating resist 11 is removed by etching. At this time, although it is not shown as a plan view, it is a thin metal! I4 is applied to the entire upper surface of the base film l and dry sheet 3, and the plating layer 12 is formed only in the lead forming area corresponding to the wiring lead 7. Therefore.

It is necessary to remove the gold f1 thin film present in each lead forming region JJn, and here a high-speed etching process is performed.
In other words, as shown in FIG.
At this time, the plating layer 12 is also exposed to the etching solution.
Although it is etched to the same thickness as I%jM4, it is formed thicker by the thickness of the metal thin film 4 as described above, so it is formed to a predetermined thickness (for example, about 20 to 40 gm).

As a result, the wiring lead 7 made of the plating layer 12 and the thin metal Fm4 is formed.

Then, as shown in FIG. 15, when the dry sheet 3 is etched and removed, the wiring leads 7 are formed on the base film 1 and protrude into the device hole 2, as in the first embodiment. A film substrate can be obtained.

The above-described method can also be applied to the case of mounting a double-sided wiring board, and the manufacturing method thereof will now be described as a third embodiment with reference to FIGS. 16 to 22. In this case as well, the same parts as in the first embodiment described above are denoted by the same reference numerals, and the explanation thereof will be omitted.

First, as shown in FIG. 16, device holes 2 and through holes 13 are formed in the base film 1 using a needle having a sharp tip.

In this case, the through hole 13 is formed into a tapered shape with a diameter of about 0.1 mm using a metal needle with a sharp tip. Then, as shown in FIG. 17, dry sheets 3.3 are laminated on the upper and lower surfaces of the base film l. Thereafter, by alternately exposing and developing the upper and lower dry sheets 3.3, as shown in FIG. Block the top and bottom. After this, the base film l
Metal thin films 4, 4 are deposited on the upper and lower surfaces of the dry sheets 3.3 and on the surfaces of the upper and lower dry sheets 3.3 by thin coating or sputtering. In this case, vapor deposition or sputtering is performed from the upper and lower surfaces of the base film 1, and the metal thin film 1 is also coated on the inner surface of the through-hole 3.

After this, as shown in FIG. 19, − upper and lower gold IIs +
Plating layer 14 is applied to the surface of 811 pattern 4.4 by electrolytic plating.
．． 14 is formed to a predetermined thickness (for example, about 20 to 40 μm). In this case, the metal thin film 4 is formed on the inner surface of the through hole 13.

The inside of the through hole 13 is also reliably coated, and the upper and lower plating layers 14, 14 are reliably electrically connected and connected.

Next, as shown in FIG. 20, the upper and lower plating layers 14.1
A photoresist 15.15 is coated on the surface of the photoresist 15.15, and the photoresist 15.15 is patterned into different shapes by exposing and developing the upper and lower sides using different photomasks, respectively. In this case, the upper photoresist 1
5 is formed at least in a location corresponding to the device hole 2 and the through hole 3, and is formed in the lower photoresist 1.
5 is formed at a location corresponding to the through hole 13,
It is not formed in a location corresponding to device hole 2.

Then, as shown in FIG. 21, photoresist) 15.
Using 15 as a mask, the plating layer 14, 14 and the metal thin films 4, 4 are sequentially etched to remove unnecessary portions. As a result, wiring leads 7 and connection leads 17 made of the plating layer 14 and the metal thin film 4 are formed on the upper and lower surfaces of the base film l, respectively. These upper and lower wiring leads 7
The connection leads 17 are connected to each other at the through hole 13.

After this, as shown in FIG. 22, the upper and lower plating layers 14.
The photoresist 15.degree. 15 is removed from the surface of the photoresist 14 by etching, and the dry sheets 3, 3 which close the upper and lower parts of the two device holes 2 are also removed by etching. As a result, a double-sided film substrate is obtained in which the wiring leads 7 and the connection leads 17 are connected to each other at the through holes 13 on the upper and lower surfaces of the base film l, and the wiring leads 7 protrude toward the inside of the device holes 2. I can do it.

Note that the present invention is not limited to the embodiments described above. For example, the double-sided film substrate may be formed by the same method as in the second embodiment. Also # below the plating layer!
In addition to vapor deposition and sputtering, the metal thin film 4 that forms the layer is
It may be formed by electroless plating or the like.

[Effects of the Invention] As explained in detail above, according to the present invention, the wiring leads made of a plating layer are formed on the base film without using an adhesive, so even if the wiring leads have a fine pitch, It is possible to ensure strong adhesion. Moreover,
Since no adhesive is used, it is possible to solve problems such as operational problems caused by insufficient electrical resistance caused by conventional adhesives. In particular, by filling device holes with an etched sheet, forming wiring leads on this sheet, and then etching and removing this sheet,
Since the wiring leads can protrude into the device hole, devices such as semiconductor chips can be bonded well using the TAB method or the like.

[Brief explanation of drawings]

FIGS. 1 to 8 are cross-sectional views showing the manufacturing process of a film substrate according to the first embodiment of the present invention, and FIGS. 9 to 15 are cross-sectional views showing the manufacturing process of the film substrate according to the second example. , 16th
22 are cross-sectional views showing the manufacturing process of the double-sided film substrate of the third embodiment. l...Base film, 2...Device hole, 3...Dry sea), 5, 12.1
4...Plating layer, 7...Wiring lead. Patent Applicant: Casio Computer Co., Ltd. Figure 16 Figure 7 Figure 9 Figure 20 Figure 21 Figure 22

Claims (1)

[Claims] A step of closing a device hole formed in a base film with an etched sheet, a step of plating the base film and the sheet to form a pattern of wiring leads in a predetermined shape, and the device. A method for manufacturing a film substrate, comprising: removing the sheet that blocks the hole.