JP2753740B2 - Method of manufacturing flexible circuit board - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an insulating base of a non-adhesive flexible single-sided conductive plate in which a conductive foil and a flexible insulating base material are bonded without the intervention of an adhesive layer. By using a flexible double-sided conductive plate formed by bonding another conductive foil to the material side via an adhesive layer, a symmetrical shape having a mounting part having a circuit wiring pattern on both sides and a single-layer circuit wiring pattern In addition to a double-sided flexible circuit board having a high-flexible flexible portion, a single-sided flexible circuit board that can form a circuit wiring pattern advantageous to heat-resistant mounting conditions by using a non-adhesive flexible single-sided conductive plate-side conductive foil. The present invention relates to a method for manufacturing a flexible circuit board that can be optionally configured in any form of a circuit board.

2. Description of the Related Art A double-sided flexible circuit board including a mounting portion having a connection end with a counterpart device or a circuit component mounting function and a bent flexible portion having a one-layer circuit wiring pattern is manufactured. As a conventional method, it is common to use a flexible double-sided conductive plate as known as a flexible double-sided copper-clad laminate as shown in FIG. That is, such a flexible double-sided conductive plate, as shown in the figure, conductive foils 12, 14 such as copper foil were separately bonded to both sides of a flexible insulating base film 10 via adhesive layers 11, 13, respectively. In the structure, in order to form a bent flexible portion, for example, a necessary circuit portion of one conductive foil 12 is removed and a mounting circuit wiring pattern is formed on the remaining conductive foil 12 portion,
Further, it is possible to simultaneously process these circuit wiring patterns by employing an etching method or the like so that a required circuit wiring pattern can be formed on the other conductive foil 14. As a practical form, in order to protect the circuit wiring pattern formed by the conductive foil 14, a cover film is adhered to the formation side of the circuit wiring pattern using an appropriate adhesive,
Further, in order to avoid the exposure of the adhesive layer 11 in the flexible portion, it is usual to attach another cover film to at least the exposed adhesive layer region with an adhesive.

"Problems to be Solved by the Invention" The structure of a flexible double-sided conductive plate such as the above-mentioned flexible double-sided copper-clad laminate has adhesive layers 11, 13 for providing conductive foils 12, 14, respectively. Since it is necessary to intervene, the low flexibility due to the thickness of the flexible double-sided conductive plate itself cannot be avoided.

Further, even in the case of the practical form, since the laminated components are not arranged symmetrically with respect to the circuit wiring pattern in the bending flexible portion as described above, it is substantially impossible to desire a high bending characteristic for the flexible portion. It is.

Therefore, when a highly flexible structure of the flexible part is required,
Without using a flexible double-sided conductive plate as shown in FIG. 5, a flexible single-sided conductive plate having only one conductive foil is prepared, and a required circuit wiring pattern is formed with the conductive foil to bend. Regarding the circuit wiring pattern in the flexible part, although other laminated components can be arranged symmetrically,
Due to the restrictions on the use of a flexible single-sided conductive plate, it is necessary to join a separately configured circuit board to the mounting part, and there are problems in terms of complexity and quality assurance due to the dispersion of processes, and the The problem of an increase in the number of steps requiring a bonding process and a decrease in yield accompanying the increase is inevitable.

Further, since the circuit wiring pattern of the mounting portion has an attribute of low heat resistance due to the interposition of an adhesive layer, it is difficult to employ a component mounting method involving high-temperature conditions or a mounting form such as wire bonding.

Of course, a non-adhesive flexible double-sided conductive plate using a polyimide-based polymer as a base member is also known, but it is necessary to construct this kind of pure non-adhesive flexible double-sided conductive plate in many technical cases. It is difficult and the products obtained are very expensive and lack practicality.

Therefore, a unique flexible double-sided conductive plate structure capable of solving these problems comprehensively is demanded.

"Means for Solving the Problems" The present invention comprises a non-adhesive flexible single-sided conductive plate in which a first conductive foil and a flexible insulating base material are joined without the interposition of an adhesive layer. By providing a flexible double-sided conductive plate configured to include a second conductive foil bonded to the insulating base material side of the flexible single-sided conductive plate via an adhesive layer,
Not only a double-sided flexible circuit board having a bending flexible portion having a high bending characteristic based on a symmetrical structure and a mounting portion integrally connected thereto, but also a component mounting means with high temperature conditions, wire bonding, etc. The present invention provides a method of manufacturing a flexible circuit board which can optionally configure both of a single-sided flexible circuit board which is optimal for the mounting form.

Therefore, the present invention comprises a non-adhesive flexible single-sided conductive plate in which a first conductive foil and a flexible insulating base material are joined without the interposition of an adhesive layer. A second conductive foil bonded to the insulating base material side of the board via an adhesive layer, and the bent flexible portion of the flexible circuit board has the second conductive foil provided without the first conductive foil. While a required circuit wiring pattern formed by the second conductive foil is configured to be arranged, the mounting portion is formed by the required circuit wiring pattern formed by the first conductive foil and the second conductive foil. To provide a double-sided flexible circuit board having a bent flexible portion configured to arrange the required circuit wiring pattern,
By providing a cover film member via an adhesive layer on the circuit wiring pattern side formed by the second conductive foil,
A structure in which the constituent members of the bent flexible portion with respect to the circuit wiring pattern are arranged symmetrically can be configured.

Then, in order to manufacture such a double-sided flexible circuit board, a non-adhesive flexible single-sided conductive plate in which the first conductive foil and the flexible insulating base material are joined without the interposition of an adhesive layer is prepared. And
A second conductive foil is bonded to the insulating base material side of the non-adhesive flexible single-sided conductive plate via an adhesive layer, and the first conductive foil region in the bent flexible portion is removed. While exposing the flexible insulating base material surface, the first conductive foil forms one circuit wiring pattern of the mounting portion, and the second conductive foil forms the other part necessary for the bending flexible portion and the mounting portion. Each step of forming the circuit wiring pattern can be adopted. In this case, the other circuit wiring pattern forming side is covered with an adhesive layer so as to form a highly bent flexible portion having a symmetric structure. The step of joining the film members can be easily performed.

Furthermore, a non-adhesive flexible single-sided conductive plate in which the first conductive foil and the flexible insulating base material are joined without the interposition of an adhesive layer is provided. Having a second conductive foil bonded to the base material side via an adhesive layer, forming a required circuit wiring pattern by the first conductive foil,
By removing or leaving the second conductive foil as it is, a single-sided flexible circuit board that is most suitable for a component mounting means involving high-temperature conditions or a mounting form such as wire bonding can be easily formed.

FIG. 1 is a partially enlarged cross-sectional view of a flexible double-sided conductive plate that is optimal for constituting the present invention. The first conductive foil 1 made of a copper foil or the like and a polyimide polymer are used. A non-adhesive flexible single-sided conductive plate 3 joined to a typical flexible insulating base material 2 without an adhesive layer interposed therebetween can be formed by a method of casting the flexible insulating base material 2 to the conductive foil 1, The conductive insulating member 2 can be formed by a sputtering method or an ion vapor deposition method on the conductive member. The present invention provides a non-adhesive flexible double-sided conductive plate 3 by bonding a second conductive foil 5 such as a copper foil to the insulating base material 2 side of the single-sided conductive plate 3 via an adhesive layer 4. It is characterized by constituting a conductive plate, and by adopting the composite conductive plate member, a unique high-flexibility double-sided flexible circuit board or a mounting heat-resistant single-sided flexible circuit board as follows. Can be easily manufactured in a selective and consistent process.

That is, when manufacturing a double-sided flexible circuit board having a mounting portion A and a bent flexible portion B continuously and integrally as shown in FIG. The foil 1 is subjected to an etching process to form one required circuit wiring pattern 1A only in the region of the mounting portion A,
Is removed by etching to expose the flexible insulating base material 2 serving as a base material. Further, in this etching process, it is easy to form another required circuit wiring pattern 5A on the second conductive foil 5, and a required portion between these two circuit wiring patterns 1A and 5A is easily formed. It is of course possible to provide an appropriate conducting portion 6 according to a conventional method.

And in such a double-sided flexible circuit board,
When the cover film member 8 for protecting the surface is bonded to the circuit wiring pattern 5A via the adhesive layer 7 as shown in the figure, as shown in FIG. Adhesive layers 4 and 7 for circuit wiring pattern 5A in
In addition, it is easy to symmetrically arrange the respective laminated members including the flexible insulating base material 2 and the cover film member 8, and the symmetrical arrangement structure provides an optimum high bending characteristic for the bending flexible portion B. It is possible to give.

On the other hand, when a heat-resistant single-sided flexible circuit board that is advantageous for component mounting means involving high-temperature conditions or a mounting mode such as wire bonding is formed using the non-adhesive flexible double-sided conductive plate of FIG. As shown in FIG. 4, the required circuit wiring patterns and connection pads 1B are patterned by etching the conductive foil 1 of the non-adhesive flexible single-sided conductive plate 3 to form the connection pads. High mounting heat resistance due to the absence of the adhesive layer for 1B can be provided. In this case, the second conductive foil 5 may be removed by etching at the same time as the patterning step or may be left as it is depending on the mounting mode.

[Effect of the Invention] As described above, the present invention joins another conductive foil to the insulating base material side of the non-adhesive flexible single-sided conductive plate via an adhesive layer to form the non-adhesive flexible double-sided conductive plate. Since it can be configured, it is possible to provide a relatively low-cost adhesive-free flexible double-sided conductive plate that is highly practical.

By using such a non-adhesive flexible double-sided conductive plate, it is possible to provide a double-sided flexible circuit board product comprising a bending flexible portion having high bending characteristics and a mounting portion with a symmetric structure.

Such a double-sided flexible circuit board product can be manufactured in high quality with high efficiency and good yield in a consistent processing step.

In addition, a single-sided flexible circuit board product having a mounting end having a structure optimal for component mounting means involving high temperature conditions or a wire bonding in a patterning process on the conductive foil side of a non-adhesive flexible single-sided conductive plate. Can also be easily configured.

As described above, by adopting one kind of non-adhesive flexible double-sided conductive plate, a flexible circuit board product having a different structure according to the application can be selectively formed.

These flexible circuit board products can be easily reduced in thickness and function as much as possible.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a non-adhesive flexible double-sided conductive plate constructed according to the present invention, and FIG. 2 is a highly flexible flexible portion manufactured using the non-adhesive flexible double-sided conductive plate. And FIG. 3 is an explanatory view of a symmetrical structure of the bent flexible portion, and FIG. 4 is a view showing a symmetrical structure of the bent flexible portion according to the present invention. FIG. 5 is a cross-sectional view of a main part of a high-heat-resistant single-sided flexible circuit board manufactured using a flexible double-sided conductive plate, and FIG. 5 is a partial cross-sectional view of a flexible double-sided conductive plate according to a conventional structure. is there. 1: First conductive foil 1A: Circuit wiring pattern 1B: Connection pad, etc. 2: Flexible insulating base material 3: Non-adhesive, flexible single-sided conductive plate 4: Adhesive layer with base material 5: Second Conductive foil 5A: Circuit wiring pattern 6: Double-sided conductive part 7: Adhesive layer of protective film 8: Cover film member

Claims (2)

(57) [Claims] 1. A non-adhesive flexible single-sided conductive plate in which a first conductive foil and a flexible insulating base material are joined without the interposition of an adhesive layer, and the non-adhesive flexible single-sided conductive plate is prepared. A second conductive foil is bonded to the insulating base material side via an adhesive layer, and the first conductive foil region in the bent flexible portion is removed to expose the surface of the flexible insulating base material. On the other hand, the first conductive foil forms one circuit wiring pattern of the mounting portion, and the second conductive foil forms the bent flexible portion and other circuit wiring patterns necessary for the mounting portion from each step. A method for manufacturing a double-sided flexible circuit board having a bent flexible portion. 2. The method according to claim 1, further comprising the step of joining a cover film member via an adhesive layer to the other circuit wiring pattern forming side so as to form a highly bent flexible portion having a symmetrical structure.
Method for manufacturing a double-sided flexible circuit board.