JP2000012627A - Manufacture of double-sided wiring film carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a double-sided wiring film carrier which is equipped with a through hole having reliability on electric continuity and charged with conductive paste. SOLUTION: In this method, manufacturing of a double-sided wiring film carrier, where metallic foils are arranged on both sides of an insulating base film, and one side of the metallic foil is a pattern layer and the other side is an earth flat layer, and a through hole made by punching to pass through between both layers is filled with conductive paste, is performed. In this case, filling of the conductive paste 11 is performed by screen printing, and at that time, a film or a sheet with a thickness of 5-100 μ is stuck in advance on the opposite face from the printed face side, and conductive paste 11 is printed and filled in reverse in the punching direction, and then the film or the sheet is peeled off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a double-sided wiring film carrier for mounting a semiconductor device having excellent high frequency characteristics.

[0002]

2. Description of the Related Art TAB (Tape Automa), which is one of the semiconductor mounting techniques, is known.
The ted bonding technology has been widely adopted in recent years, mainly in the field of mounting liquid crystal driver ICs, since it can flexibly cope with an increase in the number of pins and the size and thickness of an IC package, and is excellent in cost.

[0003] The TAB film carrier used for the above-mentioned applications is generally called a two-layer film carrier or a three-layer film carrier. The difference between the two is that an insulating layer (insulating base film) such as polyimide is used. ) And a conductive layer (pattern layer) such as copper, which has a structure as shown in FIGS.
FIG. 1A is a schematic sectional view showing an example of a two-layer film carrier, and FIG. 1B is a schematic sectional view showing an example of a three-layer film carrier. In the figure, 1 is a pattern layer, 2 is an insulating film, 3 is a device hole, 4 is an inner lead, and 5 is an adhesive layer. FIG.
In FIG. 1, a finished plating layer, a solder resist layer, and the like are omitted.

[0004] Incidentally, the use of the TAB film carrier is not limited to the use of the liquid crystal driver IC and the like, but also the
C (Application specific I)
C), BGA (Ball Grid Array), CSP (Chip Size Package), and other applications have recently been rapidly expanding. In these applications, the IC operating frequency tends to be higher and higher in the future,
There is a concern that signal distortion due to signal reflection or switching noise at the connection with the IC may become a problem.

One of the solutions is to provide a conductive layer (ground layer) also on the back surface of the base film, and to provide a conductive pattern with the pattern layer on the front surface through a through hole (via hole). The double-sided wiring film carrier has been proposed for a long time, and an example is shown in FIG. FIG. 2 is a schematic sectional view showing an example of a double-sided wiring film carrier. The same reference numerals as in FIG. 1 denote the same components, 6 denotes a solder resist layer, 7 denotes a ground layer, and 14 denotes a through hole. This film carrier has no adhesive layer between the pattern layer 1 and the insulating film 2.

The most important thing in this double-sided wiring film carrier is a method and means for establishing a reliable continuity in the through-holes not only in initial characteristics but also after the environmental test without deterioration. Japanese Patent Application Laid-Open No. Hei 5 (1993) -1971 discloses that a method of conducting through a through hole by plating, which has been conventionally attempted, has a problem in that productivity is inferior regardless of reliability.
The details are described in JP-A-326644, column 2, line 24 to column 3, line 9.

As a method for solving the above problems, Japanese Patent Laid-Open No.
Japanese Unexamined Patent Publication No. 326644 discloses a technique for improving the filling property of a conductive paste, that is, the reliability of conduction, by providing a hole for venting air in a lead pattern covering a through hole. It does not do.

Accordingly, it is an object of the present invention to provide a method for manufacturing a double-sided wiring film carrier having a through hole filled with a conductive paste and having conduction reliability.

[0009]

Means for Solving the Problems As a result of diligent studies, the present inventor has found that when filling a through-hole formed by punching with a conductive paste by screen printing, a predetermined fixed amount is previously placed on the surface opposite to the printing surface side. It has been found that the above object can be achieved by attaching a film or sheet having a thickness and printing and filling a conductive paste from a direction opposite to a punching direction.

[0010] The present invention has been made based on the above-described findings, and a metal foil is disposed on both sides of an insulating base film, one side of the metal foil is a pattern layer, the other side is a ground plane layer, and the two layers are grounded. In the method for manufacturing a double-sided wiring film carrier in which a through-hole formed by punching through is filled with a conductive paste, the filling of the conductive paste is performed by screen printing, and at this time, the surface opposite to the printing surface side A double-sided wiring film, wherein a film or sheet having a thickness of 5 to 100 μm is attached in advance, and the conductive paste is printed and filled in a direction opposite to the punching direction, and then the film or sheet is peeled off. A method for manufacturing a carrier is provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 3 is a schematic cross-sectional view showing a state in which a conductive paste is filled into a through hole in the manufacturing method of the present invention, and the same reference numerals as those in FIG.
Reference numeral 8 denotes an insulating base film having metal foils disposed on both sides, 9 denotes a film or sheet, 10 denotes a printing stage, 11 denotes a conductive paste, 12 denotes a printing squeegee, and 13 denotes a screen. FIG. 3 shows a case where there is no device hole or the like.

As shown in FIG. 3, a through hole 14 is formed in a base film 8 having a metal foil on both sides. Here, copper foil is preferably used as the metal foil, and polyimide is generally used as the base film. Through holes are created by punching.

Next, when filling the conductive paste 11 by screen printing, 5 to 1 in advance is applied to the surface opposite to the printing surface side.
A film or sheet 9 having a thickness of 00 μm is attached. When it is necessary to cure the paste at, for example, one hundred and several tens of degrees Celsius before peeling, the material of the film or sheet is preferably an engineering plastic having excellent heat resistance, such as polyimide.

The double-sided wiring film carrier obtained by the present invention has extremely fine wiring pitches and through-hole diameters as compared with a multilayer substrate. It is required that the film or sheet 9 to be adhered is coated with an adhesive having an appropriate adhesive property and an appropriate peeling property, and the thickness has an optimum range.

The reason is that the film or sheet 9
Is not merely for preventing the back circumference when the conductive paste 11 is filled. That is, it must be peeled off at an appropriate timing immediately after this step or through some steps. The conductive paste 11 ideally filled (the state of peeling is usually a dried or cured state) is meaningless if it is peeled off at the time of peeling, and even if the conductive paste 11 remains too much In the subsequent steps (especially, the most important etching step for forming a pattern), it is difficult to cope with fine pitch, which will be required in the future.

Of course, depending on the kind of the adhesive used for the film or sheet, the thickness of the film or sheet is 5 to 100 μm as described above.
Preferably it is 8-80 μm. If the thickness is too small, sufficient adhesive strength cannot be obtained, which hinders the conductive paste filling step and the subsequent steps of transportation. If the sheet is too thick, the conductive paste is likely to be peeled off when the sheet is peeled off, as shown in FIG.

The most important thing is which side of the base film, in which the through holes are formed by punching, on which surface the film or sheet is to be attached, that is, from which side the printing is performed. In the present invention, the conductive paste is printed and filled from the direction opposite to the punching direction. However, as described in a comparative example described later, when the conductive paste is printed and filled from the same direction as the punching direction, the initial characteristics (conductivity) are increased. Not only that, this has a large adverse effect on conduction reliability due to a durability test and the like.

Next, using a conventionally used general screen printing machine (the normal printing machine uses a TAB film carrier and a printing stage 1 for accurate positioning).
The conductive paste 11 is made to correspond to the position of the through hole 14 by the printing squeegee 12, but the hole diameter is slightly increased and the conductive paste 11 is passed through the screen 13 in which the hole through which the conductive paste 11 can pass is formed. printing,
That is, the conductive paste is filled.

As shown by the arrow in FIG.
2 moves. At this time, if the viscosity of the conductive paste 11 is too high, the conductive paste 11 passes through the through-holes 14 and is insufficiently filled. On the other hand, if the viscosity is too low, sufficient conduction reliability cannot be ensured as a result. The conductive paste is a non-Newtonian fluid, and its viscosity greatly depends on the shear speed, that is, the speed of the printing squeegee 12 and the like. The optimum printing conditions are determined by observing a cross-sectional photograph after printing.

After drying and curing the TAB film carrier filled with the conductive paste under the above optimum printing conditions, the film or sheet is peeled off, and thereafter, exposure, development and etching are performed in accordance with the manufacturing process of the double-sided wiring film carrier shown in FIG. Etc. to obtain the final product. FIG. 4 is a manufacturing process diagram of the double-sided film carrier of the present invention.

The technical field of the present invention relates to a method for manufacturing a double-sided wiring film carrier for mounting a semiconductor element having excellent high-frequency characteristics, as described above. On the other hand,
JP-A-239193 and JP-A-4-260390 disclose that a green sheet having a through-hole and a breathable sheet for preventing deformation are adhered to the back surface of the green sheet, and then the through-hole of the green sheet is screen-printed. A technique for filling a conductive paste with a conductive paste is disclosed. However, in the present invention, the film or sheet to be used does not necessarily have to be air-permeable, and the above technique is clearly different from the technique of the present invention. That is,
The present invention is to stick a film or sheet on which side of the tape formed through holes by punching,
In other words, from which side printing is performed has a great effect on the initial characteristics and reliability of conduction. At first glance, printing from the same direction as the punching seems to smoothly transfer the conductive paste. However, in practice, it is obvious from the comparison between FIGS. 5 and 6 that conduction reliability is inferior. However, the copper foil on the printed surface should be at least flat and not curled outward (ideally if it is curled inward), and the copper foil on the opposite side of the printed surface, ie, the surface to which the tape is to be attached In this method, it is necessary to curl the tape inward so that the adhesive layer of the tape does not come into contact with the conductive paste to be filled later, and it is necessary to perform punching under such processing conditions.

[0022]

Next, an embodiment of the present invention will be described in detail with reference to FIG.

Example 1 As shown in FIG. 3, a 200 μm thick polyimide base film 8 having a 18 μm thick copper foil disposed on both sides was punched into a 200 μm thick polyimide base film 8.
A through-hole 14 having a thickness of 50 μm was formed by punching a through-hole 14 having a thickness of 50 μm, and attached to a punched side of a polyimide film 9 having a thickness of 50 μm.

Next, using a general screen printer (normally, the TAB film carrier is suction-fixed to the printing stage 10 for accurate positioning).
The copper paste 11 was made to correspond to the position of the through-hole 14 by the printing squeegee 12, the hole diameter was slightly increased, and the copper paste 11 was printed through the screen 13 in which the hole through which the copper paste 11 could pass was formed. . Printing and filling of this copper paste were performed from the direction opposite to the punching direction.

The TAB film carrier in which the copper paste 11 was filled in the through holes 14 was dried and cured, and then the polyimide film 9 was peeled off. Thereafter, a final product was obtained based on the double-sided wiring film carrier manufacturing process shown in FIG. .
This double-sided wiring film carrier was subjected to an initial conduction test and a simple reliability evaluation test (hot oil). Table 1 shows the results. FIG. 5 is a schematic diagram showing the state of filling the through-hole with the copper paste. The simple reliability evaluation test was performed at 260 ° C. for 10 seconds and room temperature for 10 seconds.
This is a measured value after repeating 0 cycles.

Comparative Example 1 A polyimide film 9 was adhered to the side opposite to the punched side, and printing and filling of a copper paste were performed in the same manner as in Example 1 except that the copper paste was printed and filled in the same direction as the punching direction. A double-sided wiring film carrier was manufactured. An initial conduction test and a simple reliability evaluation test (hot oil) were performed on this double-sided wiring film carrier in the same manner as in Example 1. Table 1 shows the results. Also,
FIG. 6 is a schematic view showing the state of filling the through-hole with the copper paste.

[0027]

[Table 1]

As is clear from the results in Table 1 and the comparison between FIG. 5 and FIG. 6, the conduction was good in Example 1, whereas the conduction was poor in Comparative Example 1. As a result, it is found that Example 1 has higher conduction reliability than Comparative Example 1.

[0029]

As described above, according to the manufacturing method of the present invention, it is possible to obtain a double-sided film carrier filled with a conductive paste and having through holes having conduction reliability.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a two-layer film carrier or a three-layer film carrier.

FIG. 2 is a schematic sectional view showing an example of a double-sided wiring film carrier.

FIG. 3 is a schematic cross-sectional view showing a state in which a conductive paste is filled in through holes in the present invention.

FIG. 4 is a process chart showing a production process of the double-sided film carrier of the present invention.

FIG. 5 is a typical schematic view showing a state of filling a through-hole with a copper paste in Example 1.

FIG. 6 is a typical schematic diagram showing a state of filling a through-hole with a copper paste in Comparative Example 1.

[Explanation of symbols]

1: pattern layer, 2: insulating film, 3: device hole, 4: inner lead, 5: adhesive layer, 6: solder resist layer, 7: ground layer, 8: insulating base film having metal foils on both sides , 9: air-permeable film or sheet, 10: printing stage, 11: conductive paste, 12: printing squeegee, 13: screen, 14:
Through hole.

Claims (1)

[Claims] 1. A metal foil is disposed on both sides of an insulating base film, one side of the metal foil is a pattern layer, the other side is a ground plane layer, and a through hole formed by punching through both layers is conductive. In the method for producing a double-sided wiring film carrier filled with a conductive paste, the conductive paste is filled by screen printing, and at this time, a film having a thickness of 5 to 100 μm on a surface opposite to a printing surface side in advance. Alternatively, a method for producing a double-sided wiring film carrier, comprising: adhering a sheet, printing and filling the conductive paste from a direction opposite to the punching direction, and then peeling the film or sheet.