JPH06310832A - Manufacture of printed-wiring board - Google Patents

Abstract

PURPOSE:To obviate such defectives as exfoliation and defective bonding of patterns halfway in steps by a method wherein conductor patterns held on a bonding film capable of intentionally changing the bonding power thereof are integrated with a substrate and then the bonding power is decreased so as to mechanically release the bonding film only. CONSTITUTION:A substrate 5 having a trench part 5 is coated with a transfer bonding agent 8 and then another substrate 4 is pressed against the substrate 5 using a jig 9 and the bonding agent 8 to stick both substrates 4 and 5 on each other. At this time, conductor patterns 1 and the trench bottom surface of the substrate 5 are tack-set to be brought into contact with each other through the intermediary of the bonding agent 8 as the requirement for the pressurization. Next, the conductors 1 are irradiated with ultraviolet rays from the substrate 4 side to decrease the bonding power of the bonding agent 8 and then a supporting film 3 only is mechanically released. Later, the bonding agent 8 is completely set by heat treating step. Through these procedures, such defectives as release and defective bond of the patterns 1 can be obviated thereby enabling a rotary transfer to be manufactured in high yield.

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 printed wiring board, and more particularly, to fixing a conductor pattern held on an adhesive film by an adhesive so as to embed it in a concave portion on a substrate and then mechanically adhering the adhesive film. The present invention relates to a method suitable for manufacturing a printed wiring board that is peeled off and formed, for example, a rotary transformer used for a VTR or the like.

[0002]

2. Description of the Related Art As a conventional method for manufacturing a rotary transformer, an organic film on which a coil (conductor) pattern is formed and a core substrate having a groove are positioned by using holes and are bonded by an adhesive. A method of mechanically peeling and removing only the organic film is known. At this time, as a method for holding the coil (conductor) pattern on the organic film, a method using an adhesive, a method utilizing self-fusion of the film, etc. have been reported.

[0003]

The organic film provided with the coil (conductor) pattern for use in the above-described manufacturing method has an interface between the coil (conductor) pattern and the organic film under the manufacturing conditions in the process and normal handling. Does not peel off with
After being bonded to the core substrate, it is required to have the ability to be easily peeled off at the interface between the coil (conductor) pattern and the organic film. This is because if the force holding the coil (conductor) pattern on the organic film is too small, the coil (conductor) pattern will peel off from the film during handling, and if it is too large, the core substrate and coil will be removed when the film is peeled off. This is because there is a problem that peeling may occur at the interface of the conductor, resulting in defective fixation.

Moreover, when a thermosetting adhesive is used in the step of integrating the conductor pattern and the substrate, the film is melted or deformed by heat, and the desired conductor pattern shape cannot be obtained. is there. Therefore, there is also a problem that a very expensive film having high heat resistance must be used.

In addition, since the visible light does not pass through the films that have been used up to now, the positioning pattern cannot be recognized from the film side, or the film is thick even though it is translucent, and the positioning from the film side is performed. However, it is necessary to recognize the positioning mark from the pattern side and make a hole for positioning in advance, which causes a problem of increasing the number of steps.

An object of the present invention is to provide a method for eliminating such sticking defects and pattern detachment, and manufacturing a rotary transformer with good yield, enabling the use of a heat curing type adhesive, and selecting a material. To widen the range of.

[0007]

In order to achieve the above object, the present invention is a printed wiring board in which a conductor pattern held on a film and a substrate are integrated and then only the film is selectively removed. In the method of producing, a step of adhering a conductor pattern to a supporting film having an adhesive layer that transmits visible light and whose adhesive strength is reduced by ultraviolet irradiation, and heats the adhesive film to a temperature lower than the heat-resistant temperature of the supporting film. Then, the step of adhering the conductor pattern and the substrate to partially cure the adhesive, the step of irradiating the supporting film with ultraviolet rays to reduce the adhesive force of the adhesive layer, the step of peeling the supporting film, and the step of The method is characterized by having a step of heating and curing the adhesive.

[0008]

In the present invention, an adhesive whose adhesion is reduced by irradiation of ultraviolet rays is used to bond the support film and the conductor pattern. Therefore, after adhering the conductor held on the support film to the substrate, it is possible to easily peel off the support film by irradiating ultraviolet rays to reduce the adhesive strength of the adhesive. The heating temperature for adhering the conductor pattern and the substrate may be lower than the heat resistant temperature of the support film at first, and after peeling the support film, the temperature can be raised to a predetermined curing temperature for reliable adhesion. At the same time, the man-hours can be reduced by eliminating the step of drilling for positioning.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a substrate in which a conductor circuit pattern 1 and a support film 3 are integrated by an adhesive 2 whose adhesive strength can be reduced by ultraviolet irradiation.

The conductor pattern 1 may be obtained by any method, and the material thereof is not particularly limited as long as it is conductive, but, for example, copper or copper alloy can be generally used. Also, the conductor thickness is not particularly limited. The shape of the conductor pattern 1 is not particularly limited as long as it is a linear shape or a coil shape as long as it matches the intended wiring shape of the printed wiring board. In addition to the conductor pattern, a conductor other than the circuit pattern, such as a positioning pattern for transfer, may be provided as the conductor held on the film.

As the pressure-sensitive adhesive 2, a UV-curable type which is cured by irradiation with ultraviolet rays and loses its adhesiveness can be used. In addition, the adhesive strength of the adhesive 2 is 60 g / untreated in the T-shaped peel test of the conductor and the film.
10 mm or more, preferably 100 g / 10 mm or more, more preferably 150 g / 10 mm or more, and after treatment such as heating or ultraviolet irradiation, 60 g / 10 mm or less, preferably 30 g / 10 mm or less, more preferably 1
It is 0 g / 10 mm or less.

The support film 3 is not particularly limited as long as it can withstand the in-process conditions, but it is necessary to use a material that transmits visible light and ultraviolet light. A polyethylene terephthalate film is preferably used in consideration of economy.

Next, a method of manufacturing the substrate 4 including the conductor pattern 1, the adhesive 2 and the support film 3 will be described.

As the method for forming the conductor pattern 1, known plating methods, etching methods, vapor deposition methods, sputtering methods, CVD methods, screen printing methods of conductive paste, etc. can be used, but it is necessary to reduce the conductor resistance. The plating method and the etching method are preferable, and the plating method is particularly preferable from the viewpoint of pattern accuracy.

Here, the plating method will be described as an example with reference to FIG. First, as shown in FIG. 2A, a photoresist 7 corresponding to a portion other than a conductor pattern to be formed is formed on a conductive substrate 6 serving as a plating base. Then, as shown in FIG. 2B, the conductor pattern 1 is obtained by electrolytic plating using this as a cathode. Next in FIG.
As shown in (c), the film 3 coated with the adhesive 2 is attached to the conductor surface, and then the plating substrate 6 is removed to obtain the substrate 4 as shown in FIG. 2 (d). When the film is attached, it can be arbitrarily selected whether to remove the photoresist 7 or leave it as an insulating material (it is removed in FIG. 2D).

Example 1 Next, a method of manufacturing a printer wiring board using the above-mentioned substrate 4 will be described with reference to FIG. The steps are as follows.

(A) A transfer adhesive 8 is applied to the substrate 5 having grooves (FIG. 3A).

(B) The above-mentioned substrate 4 and substrate 5 are pressed by using a jig 9 and bonded by an adhesive 8 (see FIG. 3).
(B)).

(C) The support film 3 on the substrate 4 is removed (FIG. 3 (c)).

Each step will be described.

The adhesive 8 is applied to either the conductor pattern 1 to be bonded, the groove portion of the substrate 5, or both surfaces (in FIG. 3, it is applied to the substrate 5). The adhesive used may be an adhesive, an inorganic adhesive, a rubber adhesive, an epoxy adhesive, an acrylic adhesive, a urethane adhesive or the like as long as the conductor pattern 1 can be fixed to the substrate 5 to the extent that it does not hinder the subsequent steps. There is no particular limitation. The room temperature curing type is also effective because it can be cured for a short time by heat curing, but the present invention is particularly effective for the heat curing type. Also, as a method of supplying the adhesive, screen printing,
Dispenser coating, stamp coating, spray coating and the like are conceivable, but are not particularly limited. But,
Screen printing is preferred from the viewpoint of coating amount stability and workability.

Next, after positioning the substrate 4 having the conductor pattern and the substrate 5 having the groove portion, both the substrates 4 and 5 are
The conductor pattern 1 is integrated so as to be embedded in the groove.
At this time, by using a positioning pattern formed at the same time as the conductor pattern 1 for positioning, it is possible to integrate them with high positional accuracy. Since the support film used in the present invention is transparent, the positioning pattern can be recognized from the film side, and therefore it is not necessary to recognize the positioning pattern from the pattern side and make a hole for positioning in advance. The pressurizing condition must be set so that the conductor pattern 1 and the bottom surface of the groove portion of the substrate 5 can contact each other via the adhesive 8. Therefore, as shown in FIG. 3B, a convex jig 9 having a shape corresponding to the planar shape of the groove may be used. The curing at this time is carried out at a temperature at which peeling after irradiation with ultraviolet rays does not become difficult by heating and at a temperature at which the film is not deformed, and temporary curing of the adhesive is sufficient. The heating temperature is preferably higher in order to shorten the curing time, and lower in order not to cause thermal deformation of the film. In practice, it is determined by the curing characteristics of the adhesive used and the heat resistance characteristics of the film. In the case of a general epoxy adhesive using a polyester film, it can be temporarily cured in the range of room temperature to 150 ° C, but preferably room temperature to It is 120 ° C.

Next, ultraviolet rays are irradiated from the substrate 4 side to reduce the adhesive strength of the adhesive, and then the support film 3 is mechanically peeled and removed. After that, the curing of the adhesive stopped by the temporary curing is completely cured by heat treatment. The temperature at this time is set to the optimum value of the curing conditions of the adhesive used. If it is a general epoxy adhesive, the range of 100 ° C to 250 ° C,
It is preferably 120 ° C to 250 ° C. The printed wiring board 10 to which the conductor pattern 1 is transferred can be obtained by the above method.

Here, the material, dimensions, etc. of the substrate 5 having the groove are not particularly limited, but for example, the thickness is 5 mm.
Hereinafter, a plastic plate or a ceramic plate having a groove depth of 2 mm or less and a groove width of 5 mm or less is suitable.

Example 2 The present invention was applied to the production of a rotary transformer. The conductor pattern was formed by electrolytic plating, and as the support, a colorless and transparent polyethylene terephthalate film having a thickness of 0.008 mm and an adhesive uniformly applied with a thickness of 0.004 mm was used. This adhesive is cured by irradiating it with ultraviolet rays and its adhesive strength is lowered. Adhesion before UV irradiation is 160g / 10mm, 1 UV
Adhesive force after irradiation of 000 mj / cm ² is 10 g / 10 mm
(Hereinafter, a polyethylene terephthalate film and an adhesive are set together and simply referred to as a UV release film).

First, a photoresist (Nagase micro resist 74) corresponding to a portion other than a conductor pattern to be formed is formed on a 100 μm-thick plating base made of aluminum.
7 was used). By using this as a cathode and performing electrolytic copper plating, a coil pattern and a positioning pattern were simultaneously formed, and then the above-mentioned photoresist was dissolved and removed by a resist stripping solution (Nagase resist strip N530). The above-mentioned UV peeling film was attached using a laminator to the plurality of coils having different diameters and the positioning pattern surface having the typical values of the conductor thickness of 40 μm, the line width of 130 μm, the pitch of 170 μm, and the winding width of 820 μm.

Next, the plating base aluminum plate
% Aqueous solution of hydrochloric acid to remove and obtain a substrate in which the coil pattern and the positioning pattern are integrated on the UV release film.

Then, an epoxy resin adhesive (ThreeBond TB2285) is applied by screen printing to the groove of the ferrite substrate (groove depth 150 μm, groove width 1.23 mm) having grooves corresponding to the coil pattern, and then the coil is applied. After recognizing the positioning pattern from the film side and aligning the groove portion of the ferrite core with the pattern, the pattern was heat-treated at 110 ° C. for 15 minutes to be bonded. After that, the UV peeling film was irradiated with ultraviolet rays to reduce the adhesive strength, and then only the UV peeling film was mechanically peeled and removed.
At this time, the adhesive was in a semi-cured state and was not completely cured. Then, the printed wiring board (rotary transformer) as shown in FIG. 3C was obtained by re-heating at 200 ° C. for 20 minutes. In all of the 100 printed wiring boards manufactured by the above method, the coil pattern was securely fixed to the ferrite groove portion.

Comparative Example 1 A conductive pattern was formed by plating, and a general adhesive film having a total thickness of 0.065 mm was used as a support. This product is opaque red and has an adhesive force of 50 g / 10 mm.

The formation of the conductor pattern by the plating method, the resist stripping method, the conductor pattern, the dimensions of the ferrite core, etc. were the same as in Example 2. The above-mentioned adhesive film was attached using a laminator on the conductor pattern formed on the plating base.

Next, the plating base aluminum plate
% Aqueous solution of hydrochloric acid to remove and obtain a substrate in which the coil pattern and the positioning pattern are integrated on the adhesive film. However, in 20 out of 100, some of the conductor patterns were partially detached. After recognizing the positioning marks from the pattern side for the remaining 80 pieces and making holes, the holes are used to perform positioning, and then the ferrite cores are bonded in the same manner as in Example 2, and then only the adhesive film is machined. Then, the printed wiring board (rotary transformer) as shown in FIG. 3C was obtained.

Comparative Example 2 A conductive pattern was formed by plating, and a general adhesive film having a total thickness of 0.045 mm was used as a support. This product is dark brown and semi-transparent and has an adhesive force of 200 g / 10 mm.

The formation of the conductor pattern by the plating method, the resist stripping method, the conductor pattern, the dimensions of the ferrite core, etc. were the same as in Example 2. The above-mentioned adhesive film was attached using a laminator on the conductor pattern formed on the plating base.

Next, the plating base aluminum plate
By melting and removing with a hydrochloric acid aqueous solution, a substrate having a coil pattern and a positioning pattern integrated on the adhesive film was obtained. Subsequently, after recognizing the positioning mark from the pattern side and punching a hole, after bonding with the ferrite core by the same method as in Example 2 except that the hole is used for positioning, only the adhesive film is mechanically Although the peeling and removal were attempted, many of the coil patterns adhered to the adhesive, and only 5 out of 100 coil patterns were reliably fixed to the ferrite groove portion.

[0036]

As described above, according to the present invention,
Since the conductor pattern held on the adhesive film that can change the adhesive force intentionally was integrated with the substrate, the adhesive force was reduced and only the adhesive film was mechanically peeled off. It is possible to efficiently produce a printed wiring board with a high yield by eliminating the detachment of the pattern, the improper fixation, and the like.

Further, since the holding force of the conductor pattern on the substrate at the time of peeling the film may be a force of temporary hardening or the like, the film is not heated at a high temperature, so that the UV peeling film loses its UV peeling property when heated. Can be used, and you do not need to use expensive heat-resistant film,
Further, it becomes possible to use a thermosetting adhesive in the integration step.

Furthermore, since the film, which is the holding substrate, transmits visible light, the positioning pattern can be recognized through the film, so that it is not necessary to make a positioning hole in advance and the number of steps can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of a printed circuit board that holds a conductor pattern on a film with an adhesive that can change the adhesive strength.

FIG. 2 is a schematic cross-sectional view for explaining a manufacturing process of a printed circuit board.

FIG. 3 is a schematic cross-sectional view for explaining a process of a printed wiring board using the printed board shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor pattern 2 Adhesive 3 Support film 4 Printed circuit board 5 Substrate having groove 6 Plating substrate 7 Photoresist 8 Adhesive 9 Convex jig 10 Printed wiring board

Claims (1)

[Claims] 1. A method for producing a printed wiring board by integrating only a conductor pattern held on a film and a substrate, and then selectively removing only the film, wherein a visible ray is transmitted and an ultraviolet ray is irradiated. The step of adhering a conductor pattern to a support film having an adhesive layer whose adhesive strength is reduced by, by using an adhesive to heat to a temperature lower than the heat-resistant temperature of the support film to adhere the conductor pattern and a substrate to each other. Half-curing step, a step of irradiating the supporting film with ultraviolet rays to reduce the adhesive strength of the adhesive layer,
A method for manufacturing a printed wiring board, comprising: a step of peeling the support film, and a step of heating and curing the adhesive.