JP2000243791A - 2-metal TAB, double-sided CSP, BGA tape, and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Problem] The electrical connection between the front and back conductor layers is reliable.
Further, the present invention provides a two-metal TAB, a double-sided CSP, a BGA tape, and a method for manufacturing the same, which can reduce the manufacturing cost. SOLUTION: An insulating substrate and a wiring layer on at least both sides thereof are provided, the substrate has a through hole formed by a punching press, and the through hole is filled with a conductor by a punching press. A two-metal TAB, a double-sided CSP, and a BGA tape, wherein the conductor and the wiring layer are electrically connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a two-metal TAB, a double-sided CSP, a BGA tape, and a method for producing the same.

[0002]

2. Description of the Related Art Various types of wiring boards having conductor layers on the front and back surfaces have been used. Specifically, TAB (Tape Automated B) using flexible polyimide or the like for the substrate is used.
bonding) tape, CSP (Chip Size)
Package), BGA (Ball Grid Ar)
ray), FPC (Flexible Printed)
Circuit), and a so-called multilayer substrate using a rigid substrate such as glass epoxy.

As a method of manufacturing such a substrate having a conductor layer on the front and back surfaces, a hole such as a through hole or a blind via hole is previously formed in a desired portion of the substrate by a punching press, a drill, a laser beam, or the like. When laser light is used, it is necessary to remove so-called smear generated by the heat of the laser light (desmear).

Then, in a method of filling the holes with a conductive paste or the like using a screen printing machine and electrically connecting the conductor layers on the front and back surfaces (hereinafter referred to as a conductive paste printing method), through holes (through holes) are used. In the case of (1), a backing sheet or the like must be adhered after the perforation step, and then a conductive paste must be printed, cured, and peeled off the backing sheet in order to avoid the backing. In addition, in blind via holes, since it is necessary to set the opening diameter of the mask severely so that the holes can be filled quickly, the printing press is required to have accurate positional accuracy such as an image recognition device. Becomes expensive, which leads to an increase in product cost.

[0005] When plating is used, electroless copper plating or carbon or the like is adhered to the holes, and then electrolytic copper plating is performed (hereinafter referred to as a plating method). There is a problem.

[0006] Although these methods are not reliable in electrical connection, development of a new method which is further improved in cost is awaited in the art. For example, JP
Japanese Patent Application Laid-Open No. 6-19992 and Japanese Patent Application Laid-Open No. 62-81789 propose to solve this problem.

In Japanese Patent Application Laid-Open No. 59-69992, a wiring pattern having a conductive portion covering a through hole (through hole) is formed on both surfaces of an insulating substrate, and a diameter smaller than the diameter of the through hole is formed at the center of the conductive portion. Punch out the hole, contact the conductive parts on both sides, and then fix the conductive parts with a conductive member,
A method of manufacturing a through-hole printed wiring board for conducting copper foil on both sides is disclosed.

However, in this method, there is a problem that the process of forming through holes, punching out small holes, and fixing with a conductive member becomes complicated. In addition, since the conductive portion is brought into contact with the conductive portion on the other side by sagging, the surface has poor smoothness and lacks reliability of electrical connection.

In Japanese Patent Application Laid-Open No. 62-81789, a through hole (conductive hole) is formed by punching an unfired ceramic (green sheet), a conductive pin is inserted into the conductive hole, and then a screen is formed. The wiring board is manufactured by printing a conductor layer on the surface of the board by a printing method and then firing the green sheet.

This method uses a green sheet as a substrate as described above, and does not use an insulating substrate such as polyimide.

Accordingly, an object of the present invention is to provide a two-metal TAB, a double-sided CSP, a BGA tape and a method of manufacturing the same, which have a reliable electric connection between the front and back conductor layers and can reduce the manufacturing cost. It is in.

[0012]

Means for Solving the Problems As a result of the study, the present inventors have formed a through hole by a punching press, and then filled the formed through hole with a conductor by a punching press in the same manner. It has been found that this can be achieved.

The present invention has been made based on the above findings, and has an insulating substrate and a wiring layer on at least both sides thereof, the substrate having a through hole formed by a punching press, and The present invention provides a two-metal TAB, a double-sided CSP, and a BGA tape, in which a conductor is filled by a punching press and the conductor and the wiring layer are electrically connected.

Further, according to the present invention, after providing a wiring layer or a metal foil on at least both surfaces of an insulating substrate, a through hole is formed by a punching press, and then the conductor is filled in the through hole by a punching press. And a method for manufacturing a two-metal TAB and double-sided CSP and BGA tapes, wherein the two-layer TAB and the double-sided CSP and the BGA tape are electrically connected to each other.

[0015]

Embodiments of the present invention will be described below. Two-metal TAB and double-sided CSP, BGA of the present invention
The tape has an insulating substrate and a wiring layer on at least both sides thereof. A polyimide film is generally used as the insulating substrate, and the wiring layer is formed by etching a copper foil or the like. The conductor filled in the through-hole is preferably a foil or sheet of lead, tin, copper, or an alloy containing these as a main component.

Next, the two-metal TAB of the present invention and the double-sided C
A method for manufacturing SP and BGA tapes will be described. As described above, the present invention can be widely applied to a TAB tape using flexible polyimide or the like, CSP, BGA, FPC, or a so-called multilayer substrate using a rigid substrate such as glass epoxy. But here, TA
A description will be given of a method of manufacturing a so-called two-metal TAB tape having a wiring layer on both sides, particularly an application to a B tape.

FIG. 1 is a process chart showing a general method for manufacturing a two-metal TAB tape. As shown in FIG.
Sprocket holes and sometimes through holes are formed in the double-sided copper laminated polyimide tape by pressing.

Thereafter, the surface is formed, a photoresist is applied, and a wiring layer is formed on the surface by exposure, development, and etching. Next, a wiring layer is formed on the rear surface by performing exposure, development, and etching in the same manner as described above.

Finally, after a solder resist is applied by screen printing, finish plating such as gold plating is performed to improve conduction reliability, and a product is obtained.

In the present invention, in this step, a through hole is formed by a punching press, and then the conductor is filled in the through hole by a punching press in the same manner.
The conductor is electrically connected to the wiring layer or the metal foil.

In the above steps, the formation of through holes by a punching press and the timing of filling the conductor are arbitrary.
For example, after forming a wiring layer on both front and back surfaces, a through-hole may be formed, and then the through-hole may be filled with a conductor. Alternatively, a through-hole may be formed in the double-sided copper-applied tape, and the conductor may be filled in the through-hole simultaneously with the formation of the sprocket hole.

In the present invention, the formation of the through-hole
A punching machine that does not require desmearing is used, and an electric connection method is the same as in the case of punching, in which an ordinary punching press is used. That is, this is an extremely simplified manufacturing process in which a conductor such as a solder plate or a copper foil is superimposed on a substrate having holes formed by punching, punched again, and embedded with conductors in the holes, leading to cost reduction.

However, although the process is simple, selection and setting of the substrate thickness and the thickness of the conductor (plate) to be embedded (filled), the material (hardness) of the conductor (plate), punching stroke, post-processing such as caulking, etc. Is extremely important.

The thickness of the conductor (t1) and the thickness of the substrate (t2)
Has an optimal range. Preferably, 1.4 × t2 ≦ t1
≦ 0.7 × t2, more preferably 1.3 × t2 ≦ t1 ≦
0.8 × t2, more preferably 1.2 × t2 ≦ t1 ≦
0.9 × t2. Although depending on the caulking conditions described below, if it is too thick, irregularities occur on the surface of the substrate, causing problems in dimensional accuracy and the like. If it is too thin, electrical connection with the wiring layer becomes insufficient.

As described above, solder and copper foil are suitable for the material of the conductor. However, if the hardness is too high, the substrate itself becomes uneven, which is not preferable. Although the solder is soft and can be used as it is, in the case of a copper foil, it is necessary to devise a method of softening by annealing or the like. It should be noted that solder which is easy to recycle is more advantageous in terms of cost.

Although it is difficult to describe the stroke of punching with a mathematical expression like the thickness of the conductor, the punching is actually performed, and as a result, the conductor is in a state of so-called skewering with respect to the substrate. Thereafter, it is necessary to determine the stroke in a manner that is convenient for caulking.

The caulking after filling (embedding) the conductor is an important step which affects the reliability of conduction.
This is because, after embedding the conductor, in order to smoothly carry out and work in the subsequent process, and, for example, in the case of a tape-shaped substrate, it is often wound on a reel or the like in the subsequent process. This is because durability against severe bending is also required.

FIG. 2 is a schematic sectional view of the through-hole portion of the two-metal TAB according to the present invention thus obtained. In the figure, 1 denotes an insulating substrate, 2 denotes a wiring layer, and 3 denotes a conductor. As shown in FIG. 2, the wiring layers 2 on the front and back surfaces and the conductor show good electrical connection.

If the formation of the through-hole and the embedding of the conductor into the through-hole can be performed simultaneously,
Although the process will be further simplified, which will lead to cost reduction, as shown in FIG. 3, the lower end of the conductor 3 tends to be rounded, and even if caulked thereafter, the conduction reliability is poor.

When a low-melting-point metal such as solder is used, the number of steps is increased, but contact can be ensured by remelting the filling metal by reflow or the like.

As described above, the present invention relates to a TAB tape, a CSP, a BG using a flexible polyimide or the like.
A, FPC, and a so-called multilayer substrate using a rigid substrate such as glass epoxy can be widely applied.

[0032]

The present invention will be specifically described below based on examples and the like.

Example 1 (Example of manufacturing 2-metal TAB tape) A double-sided copper-clad polyimide film having a width of 36 mm (thickness of polyimide layer 50 μm)
m, copper foil thickness front and back each 18μm; trade name ESPANEX,
2N metal TA shown in FIG.
According to the manufacturing process of the B tape, a so-called two-metal TAB tape having a wiring layer on the front and back surfaces as shown in FIGS. 4 and 6 was manufactured. However, electrical connection between the front and back surfaces is not established.

FIG. 4 is a front view of the two-metal TAB tape, and FIG. 5 is an enlarged view near the land. FIG.
FIG. 7 is a perspective view from the back of the metal TAB tape, and FIG. 7 is an enlarged view near the land. 4 to 7, reference numeral 4 denotes a 2-metal TAB tape, 5 denotes a sprocket hole, and 6 denotes a land. However, since FIG. 6 is a perspective view, the wiring layer on the back surface is not shown. Here, the land means a place where a through hole is formed and a conductor is filled.

Using a punching press, this tape having wiring layers formed on the front and back surfaces by etching or the like is used as shown in FIG.
In addition, through holes were formed at the positions shown in FIG. Next, a 95-micron thick solder plate is placed on the tape,
The solder was buried (filled) by punching press again, and thereafter, the electrical connection of the front and back wiring layers was established by caulking with the press machine. For example, as shown in FIG. 2 which is a schematic cross-sectional view of a 200 μm φ hole, an ideal contact between the wiring layer and the conductor was observed, and in each through hole, sufficient conduction (<10 mΩ / hole) was obtained as a 2-metal TAB. was gotten.

[Example 2] (Example of manufacturing a two-metal TAB tape) The embedding (filling) of the conductor into the through hole is performed not after forming the wiring by etching or the like, but after forming the through hole in advance and then forming the sprocket hole. A 2-metal TAB tape was obtained by the same steps as in Example 1 except that the tape was formed and embedded in the conductor. As in Example 1, 2
Sufficient conduction (<10 mΩ / hole) was obtained as a metal TAB.

[Comparative Example 1] (Example of manufacturing a 2-metal TAB tape) Except that a through hole was not formed in advance, and a through hole was formed by a punching press and solder was filled (filled) at the same time, and thereafter caulking was performed. A two-metal TAB tape was prepared in exactly the same steps as in Example 1. That is, through holes were formed by a punching press, and at the same time, solder was buried. As a result, for example, as shown in FIG. 3 which is a schematic cross-sectional view of a 200 μmφ hole, disconnection between the wiring layer and the conductor was often observed, and sufficient conduction was not obtained as a two-metal TAB.

[Comparative Example 2] (Example of manufacturing a 2-metal TAB tape) Except that a through-hole was not formed in advance, and a through-hole was formed by a punching press and solder was filled (filled) at the same time, and thereafter caulking was performed. A 2-metal TAB tape was prepared according to exactly the same steps as in Example 2. That is, through holes and sprocket holes were formed by a punching press, and solder was embedded together. Comparative Example 1
Similarly to the above, disconnection between the wiring layer and the conductor was often observed, and sufficient conduction was not obtained as a two-metal TAB.

[0039]

As described above, the two-metal TAB and double-sided CSP and BGA tapes of the present invention have high reliability of the electrical connection between the front and back conductor layers. Further, according to the manufacturing method of the present invention, compared with the conventional plating method and conductive paste printing method, the steps are extremely simple, and the cost can be reduced. Also, because it can be manufactured in a dry process,
Since no waste liquid is used and the materials used can be recycled, this method can be said to be an excellent method from the viewpoint of environmental conservation.

[Brief description of the drawings]

FIG. 1 is a process diagram showing a general method for manufacturing a two-metal TAB tape.

FIG. 2 is a schematic cross-sectional view of a through-hole portion of a two-metal TAB according to the first embodiment.

FIG. 3 is a schematic sectional view of a through-hole portion of a two-metal TAB according to Comparative Example 1.

FIG. 4 is a front view of the two-metal TAB tape according to the first embodiment.

FIG. 5 is an enlarged view of the vicinity of a land in FIG. 4;

FIG. 6 is a perspective view of the two-metal TAB tape according to the first embodiment as viewed from the back surface.

FIG. 7 is an enlarged view near the land in FIG. 6;

[Explanation of symbols]

1: Insulating substrate (polyimide), 2: Wiring layer, 3: Conductor, 4: 2 metal TAB tape, 5: Sprocket hole, 6: Land.

Claims (8)

[Claims] An insulating substrate and a wiring layer on at least both surfaces thereof, the substrate has a through hole formed by a punching press, and the through hole is filled with a conductor by a punching press; A two-metal TAB, a double-sided CSP, and a BGA tape, wherein the conductor and the wiring layer are electrically connected. 2. The two-metal TAB and double-sided CSP, BGA according to claim 1, comprising three or more layers including a metal layer.
tape. 3. The two-metal TAB and double-sided CSP, BGA tape according to claim 1, wherein the conductor is a metal. 4. The two-metal TAB and double-sided CSP, BGA tape according to claim 3, wherein the metal is lead, tin, copper, or an alloy containing these as main components. 5. After providing a wiring layer or a metal foil on at least both sides of an insulating substrate, a through hole is formed by a punching press, and then the conductor is filled in the through hole by a punching press. Or a two-metal TAB characterized by electrically connecting a metal foil
And a method for producing double-sided CSP and BGA tapes. 6. The two-metal TAB and double-sided CSP, BGA according to claim 5, comprising three or more layers including a metal layer.
Tape manufacturing method. 7. The method for manufacturing a two-metal TAB and double-sided CSP and BGA tape according to claim 5, wherein the conductor is a metal. 8. The method according to claim 7, wherein the metal is lead, tin, copper or an alloy containing these as main components.