JPS62102589A - Manufacture of double-sided connection type flexible printedcircuit substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method of manufacturing a flexible circuit board, in particular:
The present invention relates to a method for manufacturing a double-sided flexible circuit board that is advantageous when applied to a structure in which circuit components can be connected to both sides of the circuit board by employing a pre-punch method.

"Prior Art" This type of flexible circuit board is generally constructed by forming a desired circuit pattern on one side of a suitable base film material using conductive foil such as copper foil. However, as the mounting density of circuit components increases, a configuration is used in which circuit components 20 and 21 are mounted and connected on both sides of a single layered flexible circuit board 10, as shown in FIG. In such a double-sided flexible circuit board 10, the required circuit patterns 15, 16, 17, 18, etc. are formed on the base material 11 via the adhesive layer 12 by photoetching or the like, and then the upper surface is A surface protection layer 13 such as a cover film is provided via the adhesive layer 121e, and in this example, the circuit pattern plates 16 and 17 are constructed so that the circuit components 21 can be connected from the back side by employing a pre-punch method, and the circuit components 21 can be connected from the back side. 201, connect to circuit patterns 15 and 18 from the surface as usual. It is also possible to provide the back side connection part 14 and the front side connection part 19 with the outside by a similar method.

The flexible circuit board 10 as described above includes a circuit component 20.2.
1 is mounted and connected from both sides, so it requires higher solder heat resistance and adhesive strength with the circuit pattern than other general flexible circuit boards, so this type of double-sided connection type is possible. A manufacturing method as shown in FIG. 3 is adopted for the flexible circuit board.

That is, first, an adhesive layer 2 is provided on a suitable base material 1 as shown in FIG. Rough surface 22A obtained by applying solder heat resistance treatment and adhesive strength improvement treatment
, 22B, etc., is laminated on the base material 1 via the adhesive layer 2 as shown in FIG. 22, a photoresist material 23 is applied as shown in FIG. 22 (4), and a desired circuit pattern 24.
25 and 26 as shown in FIG. 5 (5), and finally a surface protective layer as described above is provided on the circuit pattern to complete the series of steps. A part of the back side of the circuit pattern 25 is formed into a pre-punch hole 3 by removing the filling resist material 5.
Since it is exposed, connection can be made from the back side.

"Problems to be Solved by the Invention" In such a manufacturing method, the rough surfaces 22A and 22B provided on both sides of the conductive foil 22, which are necessary to ensure solder heat resistance and adhesive strength, do not, however, interfere with the circuit. Particularly in the pattern forming process, the presence of the rough surface 22A causes various problems.

That is, the rough surface 22A makes it difficult to uniformly apply the photoresist material 23, and the rough surface 22A is more likely to form air pockets.
．． 25, 26, etc., and foreign matter such as dust adheres to such a rough surface 22A, making it difficult to remove the foreign matter. This may cause pattern defects, and as a result, it becomes difficult to improve yield.

"Means for Solving the Problems" The present invention provides a double-sided connection type using pre-punch means that can achieve good circuit patterning processing without causing defects while improving solder heat resistance and adhesive strength as described above. It is an object of the present invention to provide a suitable method for manufacturing a flexible circuit board, and for this purpose, the present invention improves adhesive strength and strength only on the bonding surface with the base material after the necessary pre-punching treatment for the base material. A conductive foil treated to improve solder heat resistance is bonded to the base material, and after forming a required circuit pattern on the conductive foil having a smooth surface, the exposed surface of the circuit pattern is treated to improve adhesive strength and solder heat resistance. After applying
It is configured to form a surface protective layer.

Embodiment FIG. 1 shows a process diagram of a method for manufacturing a double-sided flexible circuit board according to an embodiment of the present invention, and the same reference numerals as in FIG. 3 represent the same elements. In the step of drilling the pre-punched holes 3 in the base material 1 provided with the adhesive layer 2 as shown in FIG. As shown in Figure (3), a conductive foil 4 having a smooth surface 4A with a rough surface 4B applied only to the bonding surface on the base material 1 side was used, and a photoresist material 6 was uniformly applied onto this smooth surface 4A. Then, as shown in FIG. 4 (4), the conductive foil 4 is subjected to a necessary first etching process and the resist material 6 is peeled off to form necessary circuit patterns 41, 42, 43, etc. as required.Circuit. Since the patterning process is thus performed on the smooth surface 4A of the conductive foil 4, it is easy to completely remove foreign substances such as dust required from the surface 4A, and
It is possible to smoothly complete this process while preventing undesirable situations such as air accumulation as in the past.

After such a circuit pattern forming process, the filling resist material 5 is removed and a round circuit pattern 4 is formed in the pre-punch hole 3.
Either the back side of the circuit pattern 41, 42, 43 is exposed, or the resist material 5 is filled as is so as to be removed in the final process, and as shown in FIG. After appropriately forming a rough surface 7 for improving adhesive strength, a surface protective layer 9 such as a cover film is provided on the circuit pattern surface via an adhesive layer 8 as shown in FIG. 6 (6), thereby completing a series of steps. can be completed efficiently.

"Effects of the Invention" According to the method for manufacturing a double-sided flexible circuit board according to the present invention, after the required circuit pattern forming process, the base material is treated to improve the adhesive strength with the surface protective layer and to improve the soldering heat resistance. Since it is configured to be applied separately from the side, it is possible to prevent defects in circuit patterns due to contamination of foreign matter such as dust or air pockets in the process of applying photoresist material to conductive foil, and to achieve a high yield. This method has the advantage of being able to efficiently manufacture a double-sided flexible circuit board using the high-quality pre-punch method at a low cost.

[Brief explanation of drawings]

Fig. 1 is a manufacturing process diagram of a double-sided flexible circuit board according to an embodiment of the present invention, and Fig. 2 is for explaining an example of mounting circuit components on this kind of double-sided flexible circuit board. FIG. 3 is a process diagram for manufacturing a double-sided flexible circuit board by a conventional method. 1: Base material 2; Adhesive layer 3: Pre-punch hole 4: Conductive foil 4^: Smooth surface 4B: Rough surface 5: Resist material 6: Photoresist material 7: Rough surface 8: Contact Layer 9: Surface protection layers 41 to 43: Circuit pattern Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In the manufacturing method of flexible circuit boards using a pre-punching method that allows circuit components to be connected to both sides of the circuit board, adhesive strength and solder are reduced only on the bonding surface with the base material after the necessary pre-punching process for the base material. A conductive foil treated to improve heat resistance is bonded to the base material, and after forming a required circuit pattern on this conductive foil, the exposed surface of the circuit pattern is treated to improve adhesive strength and soldering heat resistance. A method for producing a double-sided flexible circuit board, characterized in that it is configured to form a surface protective layer.