JP3374777B2 - 2-metal TAB, double-sided CSP, BGA tape, and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Various wiring boards have been used as wiring boards having conductor layers on the front and back surfaces. Specifically, a TAB (Tape Automated B) using a flexible polyimide or the like as a substrate.
onding) 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 for manufacturing such a substrate having conductor layers on the front and back surfaces, holes such as through holes or blind via holes are previously formed in desired portions of the substrate with a punching press, a drill, laser light or the like. When laser light is used, it is necessary to remove so-called smear (desmear) generated by the heat of the laser light.

After that, in the 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 the conductive paste printing method), through holes (through holes) are used. In this case, in order to avoid the backing, it is necessary to attach a backing sheet or the like after the perforating step, and then print and cure the conductive paste and peel the backing sheet, and then go through a long process. Also, in blind via holes, since the opening diameter of the mask must be set severely in order to fill the holes without interruption, the printing machine is required to have accurate position accuracy such as an image recognition device, and the momentum printing machine. Specifications become expensive, which in turn leads to higher product costs.

When plating is used, electroless copper plating, carbon or the like is attached to the holes, and then electrolytic copper plating is performed (hereinafter referred to as plating method). Since it is a wet method, the waste liquid is treated. There is a problem.

In these methods, there is a long-awaited need in the art for the development of new methods that are further improved in cost, regardless of the reliability of electrical connection. For example, JP-A-59
There are proposals for solving this problem in Japanese Patent Laid-Open No. 61992 and Japanese Patent Laid-Open No. 62-81789.

In Japanese Patent Laid-Open No. 59-61992, 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 in the center of the conductive portion. Punch out the holes of, contact the conductive parts on both sides, then fix the conductive parts with a conductive member,
A method of manufacturing a through-hole printed wiring board in which copper foils on both sides are electrically connected is disclosed.

However, this method has a problem that the steps of forming a through hole, punching out a small hole and fixing with a conductive member are complicated. Further, since the conductive portion comes into contact with the conductive portion on the other side due to sagging, the surface is inferior in smoothness and the electrical connection is also unreliable.

Further, in Japanese Patent Laid-Open No. 62-81789, a through hole (conduction hole) is formed by punching in an unfired ceramic (green sheet), and then a conduction pin is inserted into the conduction 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.

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

[0012]

DISCLOSURE OF THE INVENTION As a result of investigations, the inventors of the present invention have achieved the above object by forming through holes by a punching press and then filling the formed through holes with a conductor by the punching press in the same manner. We have found that it 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 surfaces thereof, and the substrate has through holes formed by a punching press, and the through holes are formed in the through holes. 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 through hole is filled with a conductor by the punching press. The present invention provides a method for manufacturing a two-metal TAB, a double-sided CSP, and a BGA tape, which is characterized by electrically connecting the wiring layer or the metal foil.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. 2-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 surfaces 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. Further, as the conductor to be filled in the through hole, a foil or sheet of lead, tin, copper, or an alloy containing these as main components is suitable.

Next, the 2-metal TAB and the double-sided C according to the present invention.
A method of manufacturing SP and BGA tapes will be described. INDUSTRIAL APPLICABILITY 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
The application to B tape, especially the method for producing a so-called 2-metal TAB tape having wiring layers on both sides will be described.

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

After that, the surface is formed and a photoresist is applied, and a wiring layer is formed on the surface by exposure, development and etching. Next, the back surface is formed in the same manner, a photoresist is applied, and a wiring layer is formed on the back surface by exposure, development and etching.

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

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

In the above steps, the formation of through holes by punching press and the filling time of the conductors are arbitrary.
For example, after forming wiring layers 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 first formed in the double-sided copper-clad tape, and the through hole may be filled with a conductor at the same time when the sprocket hole is formed.

In the present invention, the through hole is formed
Desmearing is unnecessary punching, and the method of electrical connection is the same as punching, using an ordinary punching press. That is, this is a very simplified manufacturing process in which a conductor such as a solder plate or a copper foil is superposed on a substrate having holes punched by punching, and the conductor is embedded in the holes again, resulting in 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), the punching stroke, the post-treatment such as caulking, etc. Is extremely important.

Conductor thickness (t1) and substrate thickness (t2)
There is an optimum range for. Preferably 1.4 × t2 ≦ t1
≦ 0.7 × t2, more preferably 1.3 × t2 ≦ t1 ≦
0.8 × t2, more preferably 1.2 × t2 ≦ t1 ≦
It is 0.9 × t2. Although it depends on the crimping conditions described below, if it is too thick, irregularities occur on the substrate surface, causing problems in dimensional accuracy and the like, and if it is too thin, electrical connection with the wiring layer becomes insufficient.

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

Although it is difficult to describe the punching stroke by a mathematical expression like the thickness of the conductor, the punching stroke is actually punched, and as a result, the conductor becomes a so-called skewered state on the substrate, It is necessary to determine the stroke so as to be convenient for the subsequent crimping.

Further, the caulking after filling (embedding) the conductor is an important step which influences the reliability of conduction.
This is because, after embedding the conductor, it is possible to smoothly carry or work in the subsequent steps, and, for example, in the case of a tape-shaped substrate, it is often wound up on a reel or the like in the subsequent steps. This is because it is also required to have durability against bending.

FIG. 2 shows 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 is an insulating substrate, 2 is a wiring layer, and 3 is a conductor. As shown in FIG. 2, the wiring layers 2 on both front and back surfaces and the conductors show good electrical connection.

If formation of a through hole and embedding of a conductor in the through hole can be performed at the same time,
Although the process may be simplified and the cost may be reduced, as shown in FIG. 3, the lower end of the conductor 3 tends to be rounded, and even if the caulking is performed thereafter, the conduction reliability is poor.

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

The present invention, as described above, uses TAB tape, CSP, BG made of flexible polyimide or the like.
It can be widely applied to A, FPC, so-called multi-layer substrate using a rigid substrate such as glass epoxy.

[0032]

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

Example 1 (Production Example of 2-Metal TAB Tape) 36 mm wide double-sided copper-bonded polyimide film (polyimide layer thickness 50 μm)
m, copper foil thickness 18 μm on each side; trade name Espanex,
2-metal TA shown in FIG. 1 using Shin Nippon Chemical Co., Ltd.)
According to the manufacturing process of the B tape, a so-called 2-metal TAB tape having wiring layers on the front and back surfaces as shown in FIGS. 4 and 6 was manufactured. However, the electrical connection on the front and back is not made.

FIG. 4 is a front view of the 2-metal TAB tape, and FIG. 5 is an enlarged view of the land and its vicinity. 2 in FIG.
FIG. 7 is a perspective view from the back surface of the metal TAB tape, and FIG. 7 is an enlarged view of the vicinity of the land. 4 to 7, 4 is a 2-metal TAB tape, 5 is a sprocket hole, and 6 is a land. However, since FIG. 6 is a perspective view, the wiring layer on the back surface is not shown. In addition, the land here means a portion where a through hole is formed and a conductor is filled.

This tape having a wiring layer formed on the front and back surfaces by etching or the like is formed by using a punching press machine as shown in FIG.
A through hole was formed at the position shown in FIG. Next, overlay the solder plate with a thickness of 95 microns on the tape,
By punching and pressing again, the solder was embedded (filled), and then caulking was also performed by the pressing machine to electrically connect the front and back wiring layers. For example, as shown in FIG. 2, which is a schematic cross-sectional view of a 200 μmφ hole, ideal contact between the wiring layer and the conductor is observed, and sufficient conduction (<10 mΩ / hole) as a 2-metal TAB is observed in any of the through holes. was gotten.

Example 2 (Manufacturing Example of 2-Metal TAB Tape) Embedding (filling) of a conductor in a through hole is not performed after forming a wiring by etching or the like, but after forming a through hole in advance, a sprocket hole is formed. A two-metal TAB tape was obtained by the same steps as in Example 1 except that the two-metal TAB tape was formed and simultaneously embedded in the conductor. As in Example 1, in any of the holes, 2
Sufficient conduction (<10 mΩ / hole) was obtained as a metal TAB.

Comparative Example 1 (Example of Manufacturing Two-Metal TAB Tape) Except that through holes were not formed in advance, through holes were formed by punching press and solder was filled (filled) at the same time, and then caulking was performed. A two-metal TAB tape was prepared according to the same steps as in Example 1. That is, a through hole was formed by punching press and at the same time, solder was embedded. As a result, for example, as shown in FIG. 3, which is a schematic cross-sectional view of the 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 (Production Example of 2-Metal TAB Tape) Without forming through holes in advance, formation of through holes by punching press and embedding (filling) of solder were carried out at the same time, and then caulking was performed. A two-metal TAB tape was prepared according to the same steps as in Example 2. That is, through holes and sprocket holes were formed by a punching press, and solder was also embedded. 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 2-metal TAB.

[0039]

As described above, the two-metal TAB, double-sided CSP, and BGA tape of the present invention have high reliability of electrical connection between the front and back surface conductor layers. In addition, the manufacturing method of the present invention enables extremely simple steps and cost reduction as compared with the conventional plating method and conductive paste printing method. Also, since it can be manufactured in a dry process,
It can be said that it is an excellent construction method from the viewpoint of environmental protection, since there is no waste liquid and the used materials can be recycled.

[Brief description of drawings]

FIG. 1 is a process drawing showing a general manufacturing method of a 2-metal TAB tape.

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

FIG. 3 is a schematic cross-sectional view of a through-hole portion of a 2-metal TAB according to Comparative Example 1.

FIG. 4 is a surface view of a 2-metal TAB tape according to Example 1.

FIG. 5 is an enlarged view of the vicinity of the land of FIG.

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

FIG. 7 is an enlarged view of the vicinity of the land of FIG.

[Explanation of symbols]

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

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-226423 (JP, A) JP-A-9-232381 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/60 H01L 23/12

Claims (8)

(57) [Claims] 1. 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 through hole is filled with a conductor by the 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 the double-sided CSP and BGA according to claim 1, which are composed of three or more layers including a metal layer.
tape. 3. The two-metal TAB, the double-sided CSP, and the BGA tape according to claim 1, wherein the conductor is a metal. 4. The two-metal TAB, double-sided CSP, and BGA tape according to claim 3, wherein the metal is lead, tin, copper, or an alloy containing these as the main components. 5. A wiring layer or a metal foil is provided on at least both surfaces of an insulating substrate, a through hole is formed by punching press, and then the conductor is filled in the through hole by punching press to form the conductor and the wiring layer. Alternatively, a two-metal TAB characterized by electrically connecting a metal foil
And a method for manufacturing double-sided CSP and BGA tape. 6. The two-metal TAB and the double-sided CSP and BGA according to claim 5, which are composed of three or more layers including a metal layer.
Tape manufacturing method. 7. The method for manufacturing a two-metal TAB, a double-sided CSP, and a BGA tape according to claim 5, wherein the conductor is a metal. 8. The method for producing a two-metal TAB, a double-sided CSP, and a BGA tape according to claim 7, wherein the metal is lead, tin, copper, or an alloy containing these as main components.