JP2734184B2 - TAB tape carrier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a highly reliable TAB tape carrier with a reduced thickness of an adhesive.

<Prior Art> As a conventional TAB tape carrier, there is one shown in FIG. 1, for example. Generally, TAB tape carrier 1 is
An insulating film 3 such as an organic polyimide film or a glass epoxy film having a thickness of 70 to 125 μm and a width of 35 mm (or a width of 70 or 140 mm or the like) is punched.
A device hole 6 corresponding to an IC element (not shown) and a pilot hole 7 for sending out a tape carrier body at the time of mounting are formed.
After bonding a copper foil such as a rolled copper foil or an electrolytic copper foil having a thickness of 18 to 35 μm via an adhesive 4 of about 20 μm, a predetermined wiring pattern is formed by photoetching. Second
The figure shows a cross-sectional view of a wiring pattern portion, in which a copper foil 2 and an insulating film 3 are bonded via an adhesive 4 to form a three-layer structure.

In the TAB structure shown in FIG. 2, the thickness of the normal adhesive 4 is 15
2020 μm is selected. The reason for this is that the surface on the side to be pasted with the adhesive of the conventional copper foil has been roughened to an average roughness of 0.8 to 2.0 μm (hereinafter referred to as Ra), and has sufficiently penetrated the roughened surface of the copper foil. This is because a thickness of 15 to 20 μm was required as the amount of the adhesive.

However, recently, the finer wiring of TAB tape carriers has progressed, and in the case of the roughened surface of conventional copper foil, copper foil remains between patterns after photoetching is completed, and the occurrence of a short circuit in the wiring pattern becomes a problem. It has become. That is, the projections on the roughened surface of the copper foil penetrate into the adhesive and are difficult to be removed by etching, so that even after the completion of the etching, they remain in a dot-like manner between the wiring patterns (portions where the copper foil is desired to be dissolved), and this migrates when voltage is applied. It has been clarified that this may cause a short circuit or the like.

As a countermeasure, AC electrolytic roughening method using minute current and fine particle electrodeposition roughening method by electroplating method have been remarkably advanced recently, and so-called low-roughened copper foil can be manufactured.

Since this low-roughened copper foil can reduce the above-mentioned problems, generally, a low-roughened copper foil having a Ra of 0.2 to 0.4 μm has been favorably used.

On the other hand, the adhesive is used in a conventional thickness of 15 to 20 μm. This is because a film of polyimide or the like with an adhesive having this thickness is easily available as a commercial product.

<Problems to be Solved by the Invention> The present inventors investigated the effects of adhesives, and found that chlorine ions generated by decomposition in the case of epoxy type and ammonia generated by decomposition of amine type curing agent used in the curing agent are particularly metal. Clarified the phenomenon that causes corrosion.

That is, not only does the copper pattern corrode in a constant temperature and humidity test and a high temperature heating test at 65 ° C. × 95% RH, but also causes a migration short circuit in a DC bias application test.

Further, epoxy as an adhesive is hard because it is a thermosetting type, and when it is bent, the adhesive cracks and causes copper foil pattern peeling.

Further, the adhesive is easily broken in the TAB tape manufacturing process, and is likely to be powdery and adhere to the surface after the photoresist coating, which causes pattern connection and chipping.

An object of the present invention is to provide a TAB tape carrier having few pattern defects and few migration short circuits.

<Means for Solving the Problems> According to the present invention, in order to achieve the above object, in a tape carrier formed by bonding a copper foil on an insulating film using an adhesive to form a wiring pattern, The thickness of the agent is set to 3 to 7 μm, and the average roughness Ra of the roughened surface on the bonding side of the copper foil is set to 0.1 to 0.4 μm.
A TAB tape carrier is provided.

Here, it is preferable that electroless tin plating or air solder plating is applied to the upper part of the wiring pattern.

Hereinafter, the present invention will be described in detail with reference to FIG. 1 and FIG.

TAB tape carrier 1 is made of flexible insulating film 3
Then, necessary through holes such as a device hole 6, a pilot hole 7 and the like are opened, a copper foil is adhered to the film, and the copper foil is processed by etching to form an inner lead electrically connected to the semiconductor element. And a lead pattern having outer leads.

In the present invention, the TAB tape carrier 1 is made of a resin such as a polyimide resin, a polyethylene resin, a polyester resin, a glass epoxy resin, or a flexible epoxy resin, or a flexible or insulating material such as paper. A lead 5 on which a copper foil 2 having a desired pattern is adhered is adhered by an adhesive 4 to a portion of the film 3 excluding the element mounting portion 6.

The lead 5 is made of an insulating film 3 as shown in FIG.
, Adhesive 4 and copper foil 2.

The copper foil 2 is preferably a rolled copper foil or an electrolytic copper foil.

Ra of the surface of the copper foil 2 in contact with the adhesive 4 is 0.1 to 0.4 μm.
m. If Ra exceeds 0.4, copper foil remains between the patterns after etching. If the Ra is less than 0.1, the processing cost is high.

The adhesive 4 is not limited, but is preferably an ordinary epoxy type, a low chlorine ion migration resistant epoxy type (resin obtained by washing and extracting residual chlorine ions with a solvent) or a polyetheramide type. The composition of the adhesive is not limited, and a known adhesive can be used as it is.

The thickness of the adhesive 4 is 3 to 7 μm. 7 thickness
If it exceeds μm, corrosion of the copper foil pattern cannot be prevented. When the thickness is less than 3 μm, the adhesive effect of the adhesive is insufficient, and the copper foil pattern is peeled off.

The upper portion of the wiring pattern is subjected to electroless tin plating or electric solder plating for bonding with the element electrode portion, to obtain a finished product. The thickness of this plating layer is 0.5 ~ 1.0μm
But the degree is good.

<Example> Hereinafter, the present invention will be specifically described based on examples.

The following polyimide film is coated with the following epoxy-based adhesive to a thickness of 7 μm, a device hole is opened with a press die, and the following copper foil is adhered to the part excluding the element mounting part. Form a pattern, apply electroless tin plating on top of it and TAB
Tape carrier was created.

(Example 1) Number of inner lead pins: 200 Inner lead pitch: 0.1 mm Inner lead width: 0.05 mm Copper foil: 0.035 µm thickness, 26.4 mm width oxygen-free copper rolled copper foil (Ra on the roughened surface: 0.4 µm) Adhesive: Epoxy adhesive, curing agent amine, binder latex 10% Film: Polyimide film 0.075mm thickness, 35mm width Plating: Electroless tin plating 0.5μm Roller for coating adhesive on polyimide film A coating method was used. For comparison, the following four tests were carried out using a 19 μm coated adhesive (Comparative Example 1) and a commercial product coated with the same epoxy adhesive and 19 μm (Comparative Example 2). Performed and compared.

Each TAB tape carrier was tested before tin plating.

Constant temperature, constant humidity bath test: Observation of discoloration of plated surface after standing at 65 ° C x 95% RH for 24 hours High temperature test: Observation of discoloration of plated surface after standing at 150 ° C x 10 hours in air PCT test Observe the discoloration of the plated surface after standing at 121 ° C and 2 atm for 20 hours. Bias voltage application migration test: 8 pairs (16 leads) in the 200-pin wiring. Voltage: 28 V Atmosphere: 65 ° C. × 95% RH Time: 500 hours The test results are shown in Table 1.

The results in Table 1 clearly show the effect of thinning the adhesive. This effect was considered to be due to the substantial decrease in the basis weight of the adhesive, and it was confirmed that this could significantly improve the reliability.

Next, the above TAB tape carrier before tin plating was sandwiched in a 0.1R jig, bent 90 degrees to the copper foil 2 side (anti-insulating film side), and returned to the original position. The number of occurrences of pattern defects was checked.

 Table 2 shows the results.

The bending was repeated for each of the TAB tape carriers after tin plating, and the occurrence of pattern defects (disconnection, connection) was observed with a stereoscopic microscope (magnification: 20) each time. Was used as the number of times of folding, and 20 pieces were tested.

 Table 3 shows the survey results.

From the investigation results in Tables 2 and 3, it can be seen that the pattern defects of the examples are significantly reduced. This is because, in the present invention, the problem that the adhesive flies in drilling holes for device holes, pilot holes, etc. is reduced in the present invention. This is because it is difficult to get out.

Regarding the bending resistance, when the adhesive is thick, the elongation applied to the adhesive and the compressive stress increase, so that the separation from the copper foil is easy to proceed. , The folding resistance is improved.

<Effects of the Invention> Since the present invention is configured as described above, the TAB tape carrier of the present invention has few pattern defects and few migration short circuits.

Further, since the powder is hardly generated at the time of drilling the hole due to the reduced thickness of the adhesive, the adhesive can be applied to the entire surface up to the pilot hole portion. Therefore, since the adhesive in the conventional TAB tape carrier easily generates powder, the adhesive cannot be applied to the sprocket holes because the pilot holes are used as sprocket holes in the manufacturing process. Since it can be applied to the entire surface, the cost of applying and processing the adhesive can be reduced. That is, there is no need to partially coat the film in the width direction at the center in the width direction, and after coating the film material with a width of 500 to 1000 mm, it can be used by freely slitting it to a width of 35 to 70 mm, with adhesive The cost can be reduced by about 10% as a polyimide film.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a TAB tape carrier. FIG. 2 is a cross-sectional view of the wiring pattern portion of FIG. DESCRIPTION OF SYMBOLS 1 ... TAB tape carrier, 2 ... copper foil, 3 ... insulating film, 4 ... adhesive, 5 ... lead, 5a ... inner lead, 6
... Element mounting part (device hole), 7 ... Pilot hole

Claims (2)

(57) [Claims] 1. A tape carrier formed by bonding a copper foil on an insulating film using an adhesive to form a wiring pattern, wherein the adhesive has a thickness of 3 to 7 μm, A TAB tape carrier, characterized in that the average roughness Ra of the roughened surface is 0.1 to 0.4 μm. 2. The TA according to claim 1, wherein an electroless tin plating or an air solder plating is applied to an upper portion of the wiring pattern.
Tape carrier for B.