JP2003198123A - Flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed wiring board which has improved, with a comparatively simplified method, the adhesive strength of an adhesive agent layer between the copper wiring circuit on the copper-clad laminated plate and a coverlay film with the adhesive agent. <P>SOLUTION: In the flexible printed wiring board where a copper-clad laminated plate and the coverlay film with adhesive agent layer are bonded, the adhesive agent layer of the coverlay film is bonded via a layer of triazinethiol having a particular chemical structure provided on the surface of copper wiring circuit of the copper-clad laminated plate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed wiring board comprising a copper-clad laminate and a cover lay film with an adhesive layer, and a triazine thiol layer on the copper circuit surface of the copper-clad laminate with wiring circuits The present invention relates to a flexible printed wiring board in which the adhesive strength of the cover lay film with the adhesive layer is improved by providing.

[0002]

2. Description of the Related Art A flexible printed wiring board is usually formed by forming a wiring circuit on a copper layer of a copper-clad laminate by various methods, and then laminating it with a coverlay film with an adhesive.
It is manufactured by curing this. Then, the copper-clad laminate, roughened rolled copper foil or electroplated copper foil, so that the copper layer and its base material are firmly adhered, such as a polyimide film with an epoxy resin adhesive. It is glued to the base material. Then, the copper-clad laminate is cleaned by mechanical polishing and chemical polishing so that the etching resist and the copper foil strongly adhere to each other on the surface of the copper foil, and then resist formation and circuit formation etching are performed. Then, the coverlay film is attached to the circuit copper foil, and in order to improve the adhesion between the circuit copper foil and the coverlay film, the circuit forming copper foil is cleaned by cleaning the circuit surface. However, the modification of the surface properties was weak and sufficient adhesion could not be obtained.

Various attempts have been made to solve this problem. For example, improving the adhesive strength by improving the adhesive, but because this is done by adding new components to the adhesive, migration occurs, the price of the adhesive increases and the handling is changed. It was not so preferable because it caused problems in work. Therefore, it has been desired that this problem can be solved relatively easily without changing the current work procedure or the like.

[0004]

SUMMARY OF THE INVENTION Therefore, the problem to be solved by the present invention is a relatively simple method for forming a copper wiring circuit on a copper-clad laminate and an adhesive layer of a coverlay film with adhesive. It is intended to provide a flexible printed wiring board having a significantly improved adhesive strength.

[0005]

The problem to be solved is a flexible printed wiring board comprising a copper-clad laminate and a coverlay film with an adhesive layer according to claim 1, wherein a wiring circuit is formed. The problem can be solved by adhering it to the adhesive layer of the coverlay film via a layer of triazine thiol provided on the surface of the copper wiring circuit of the copper-clad laminate.

Further, as described in claim 2,
The triazine thiol has the following chemical structural formula (1).
And the R group of the chemical structural formula (1) is —N (C_FourH
₉) _TwoOr-NHC₆H₅To use what is
Therefore, it is solved.

[Chemical 2]

Further, as described in claim 3, the adhesive strength between the triazine thiol layer and the adhesive layer of the coverlay film has a peeling force (N / mm) of 1.
It is solved by setting it to 2 or more.

As described above, in the flexible printed wiring board, by forming the triazine thiol layer on the copper foil circuit of the copper-clad laminate, the adhesive strength of the coverlay film with the adhesive is significantly improved. Moreover, since the obtained flexible printed wiring board can have a peeling force (N / mm) of 1.2 or more, it has excellent bending resistance and folding resistance.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The invention described in claim 1 is a flexible printed wiring board comprising a copper-clad laminate and a coverlay film with an adhesive layer, and a triazine provided on the surface of the copper wiring circuit of the copper-clad laminate on which a wiring circuit is formed. A flexible printed wiring board characterized by being bonded to an adhesive layer of the cover lay film via a thiol layer, wherein a coating layer of triazine thiol or the like is provided on the surface of the copper wiring circuit and the cover. This is to bond the adhesive of the ray film. This triazine thiol was developed as a cross-linking agent for synthetic rubber, and is also used for adhesion of polymers and metals and for metal surface treatment.

When the present inventor focused on this material and studied the improvement of the adhesive strength for flexible printed wiring boards, it was found that a specific triazine thiol had an improved adhesive force. That is, in the triazine thiol represented by the chemical structural formula (1), the R group is —NHC.
_{The 6} H ₅ or -N (C ₄ H ₉ ) ₂ structure has a peeling force (N / mm) which is conventionally not treated,
It was found to improve by more than 20%. Further, when the R group was -SH, almost no improvement was observed. Thus, it was confirmed that by interposing a specific triazine thiol between the copper wiring circuit of the flexible printed wiring board and the adhesive of the coverlay film, the adhesive strength thereof can be improved.

The formation of the triazine thiol layer is carried out by immersing the flexible printed wiring board after circuit formation in the triazine thiol dissolved in a solvent, or by spraying this triazine thiol solution onto the flexible printed wiring board after circuit formation. Alternatively, it can be performed by a method such as coating with a roll. Examples of the solvent include methanol, acetone, toluene, cyclohexane, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone (MEK), tetrahydrofuran (TH
F), dimethylformamide (DMHA) or the like is used, and it is effective to use a triazine thiol solution having a concentration of 0.1 to 5% (Wt). This is because if the amount of triazine thiol added exceeds 5% (Wt), the viscosity of the solution becomes high and the triazine thiol layer becomes non-uniform when applied, resulting in variations in adhesive strength. Also,
This is because if the added amount is less than 0.1% (Wt), the triazine thiol layer obtained becomes thin and sufficient adhesive strength cannot be obtained. Among them, those in the range of 0.1 to 3% (Wt) have a higher peeling force and are preferable.

Further, as described in claim 3, the adhesive strength between the triazine thiol layer and the adhesive layer of the coverlay film has a peeling force (N / mm) of 1.
When the number is 2 or more, the obtained flexible printed wiring board has significantly improved bending resistance and folding resistance.
That is, when the peeling force is 1.2 (N / mm) or more, the bending resistance and the folding resistance are 120% or more as compared with the conventional untreated flexible printed wiring board, which is excellent flexibility. It can be a printed wiring board.

As described above, in a flexible printed wiring board in which a copper-clad laminate and a coverlay film with an adhesive layer are laminated, it is provided on the copper wiring circuit surface of the copper-clad laminate on which a wiring circuit is formed. By adhering to the adhesive layer of the coverlay film via a layer of the triazine thiol, in particular the triazine thiol having the chemical structural formula (1) as described in claim 2, Since the adhesive strength of the coverlay film with the adhesive can be significantly improved and the peeling force (N / mm) is 1.2 or more, the obtained flexible printed wiring board is Compared with the flexible printed wiring board described in (1) above, it can be made to have excellent bending resistance and folding resistance.

[0014]

EXAMPLES The effects of the present invention will be described below with reference to examples. For the various samples listed in Table 1, the peeling force (N
/ Mm) was measured according to JIS standard C6471. In addition, bending resistance and folding endurance tests were performed according to JIS standard C5016. The sample was a commercially available copper-clad laminate (Nikkalex F-32VC1 manufactured by Nikkan Kogyo Co., Ltd.).
The copper surface of is subjected to soft etching with sulfuric acid / hydrogen peroxide and then immersed in a solution of various triazine thiols,
Air dried at room temperature until the odor of the solvent was gone. This was placed facing the adhesive layer of a cover lay film with an adhesive (Nikkalex CKSV, manufactured by Nikkan Kogyo Co., Ltd.) and bonded at a temperature of 160 ° C. and a pressure of 3 MPa for 60 minutes. As a comparative example, a triazine thiol having an R group of —SH was prepared in the same manner as in the example, and a conventional flexible printed wiring board not treated with triazine thiol was used.

[0015]

[Table 1]

As is clear from Table 1, the results are shown in Examples 1 to 1.
8 indicates the target peeling force (N / m
m). Further, it can be seen that the bending resistance and the folding resistance are also improved. What was described as a comparative example with respect to such an example was that the peeling force was less than or equal to the target value, and the bending resistance and the folding resistance were not satisfied. Thus, it can be seen that the triazinethiol also has different peeling force depending on the type of R group in the chemical structural formula (1) and the solution concentration. That is, the triazine thiol is preferably one in which the R group is —NHC ₆ H ₅ and —N (C ₄ H ₉ ) _{2 and} the one in which —SH is almost the same as that without any treatment, and has an adhesive force. It can be seen that it does not contribute to the improvement of. Further, the concentration should be in the range of 0.1 to 5% (Wt), but when it becomes 5%, the numerical value slightly decreases, so 0.1 to 3% (Wt) is preferable. The types of solvents listed in Table 1 are also preferable. Further, it is understood that the one having a peeling force of 1.2 or more has improved bending resistance and folding resistance as the flexible printed wiring board as compared with the untreated one (Comparative Example 4). .

[0017]

As described above, the flexible wiring board of the present invention is a flexible printed wiring board in which a copper-clad laminate and a coverlay film with an adhesive layer are laminated to each other. A layer of the triazine thiol represented by the chemical structural formula (1) is provided on the surface of the copper wiring circuit, and the triazine thiol layer of the chemical structural formula (1) is bonded to the adhesive layer of the coverlay film. ) R group is -N (C
₄ H ₉₎ The use of a _two or -NHC ₆ H ₅ and the solution concentration of 0.1% to 5% by the (Wt), significantly improves the adhesion strength between the adhesive of the coverlay film Can be made. When the peel strength (N / mm) of the adhesive strength is 1.2 or more, the obtained flexible printed wiring board can have excellent bending resistance and folding resistance. Also, the manufacturing method thereof can be easily carried out by a method such as dip coating, spraying or coating with a roll, and there is no problem of changing the manufacturing process.

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Claims (3)

[Claims] 1. A flexible printed wiring board comprising a copper-clad laminate and a coverlay film with an adhesive layer, wherein a triazine thiol layer formed on the copper circuit surface of the copper-clad laminate having a wiring circuit is interposed. A flexible printed wiring board, which is adhered to the adhesive layer of the coverlay film. 2. The triazine thiol has the following chemical structural formula (1): And the chemical formulas R group (1) is, _-N (C _{4 H} 9)
The flexible printed wiring board according to claim 1, characterized in that ₂ or -NHC ₆ H _5. 3. The peel strength (N / mm) of the adhesive strength between the triazine thiol layer and the adhesive layer of the cover lay film is 1.2 or more. The flexible printed wiring board according to any one of 1.