JP5190696B2 - Method for producing flexible printed wiring board sheet - Google Patents

Description

The present invention relates to a manufacturing method of a flexible printed circuit board sheet to a flexible printed wiring board is provided with a plurality.

  A wiring board (hereinafter referred to as “magnetic head wiring board”) in which a supporting metal foil for supporting a magnetic head of a hard disk device and wiring for signal transmission are integrated is an information density of a perpendicular magnetic recording system or the like. With the increase, demand is further increasing. The magnetic head wiring board is manufactured in units of sheets, and several tens of magnetic head wiring boards are provided in one sheet. This is called a flexible printed wiring board sheet. A single flexible printed wiring board sheet is provided with a plating frame, and several tens of identical wiring patterns (magnetic head wiring boards) are formed connected to the plating frame. Wiring, a plating frame, a plating lead part, etc. are formed of a copper plating layer. Further, a gold plating layer is formed on a predetermined portion (connection portion) of the wiring using the above-described plating frame. In each magnetic head wiring board, a plurality of wirings are arranged in parallel, and the plating lead portion extends from the root of the wiring and is connected to the plating frame to be conductive. On the other hand, at the tip on the opposite side, the plurality of wires extend. After the formation of the gold plating layer and other series of processes, a flexible printed wiring board sheet is completed, and the flexible printed wiring board sheet is shipped to an intermediate product manufacturer or a magnetic head wiring board embedded manufacturer.

From the above, it can be seen that in the production of the flexible printed wiring board sheet, the plating process is an important process such as copper plating of the wiring and gold plating of the predetermined part of the wiring. In particular, it is important to obtain a plating layer having a highly accurate thickness and a uniform thickness throughout. Therefore, during the plating process of the flexible printed wiring board sheet, a plating solution is sprayed onto the wall surface of the plating tank to generate a reflected flow, and the surface of the circuit board and the anode on the cathode side is in this reflected flow. A method of performing plating treatment by arranging them in parallel is disclosed (Patent Document 1).
JP 2003-247099 A

The above-described measures for generating a reflected flow and arranging circuit boards and the like in the reflected flow have certain effects. However, if the outer frame part of the flexible printed wiring board sheet is wide and the area of the outer frame part is much larger than the area of the product area inside the sheet on which the flexible printed wiring board is arranged, the current adjustment for the product area is not possible. It becomes difficult. In particular, the end portion of the outer frame portion has a large amount of metal that precipitates around the plating solution due to a slight shift in the positional relationship with the plated metal plate of the facing counterpart, and causes an unstable action peculiar to the end portion. As a result, when different types of flexible printed wiring boards are manufactured in the form of a flexible printed wiring board sheet, it becomes impossible to finely adjust the plating treatment conditions (current density, etc.) for the product region according to the types. For example, it becomes difficult to accurately form the plating film thickness to the intended thickness with the total current and time of the entire apparatus. In each plating process, the conductor thin film is exposed at the outer frame portion. Although the gold plating process is limited to a predetermined region, the copper plating wiring layer is exposed in addition to the conductor thin film.
If the outer frame portion can be eliminated, fine adjustment of the current density in the product area is facilitated. However, the outer frame portion is necessary for the arrangement of the guide marks, the alignment holding portion at the time of exposure of the plating mask, the handling, the securing of strength for protecting the product area, and the like. For this reason, after providing an outer frame part, the countermeasure which can adjust the electric current etc. with respect to a product area | region is requested | required according to the kind of flexible printed wiring board.
The present invention, in the plating process of the flexible printed wiring board sheet manufacturing process with an outer frame portion, easier to current adjustment of product area, and an object thereof is to provide a method of manufacturing a flexible printed wiring board sheet.

The manufacturing method of the flexible printed wiring board sheet | seat of this invention manufactures a flexible printed wiring board sheet | seat provided with two or more flexible printed wiring boards containing a metal plating layer. The flexible printed wiring board sheet has an outer frame portion that extends over the entire circumference and a product region that is surrounded by the outer frame portion to form a flexible printed wiring board. In this manufacturing method, the outer frame portion and the product region common to the steps of forming a substrate sheet which is an intermediate product of the flexible printed circuit board sheet provided with a stainless steel foil / insulating film / conductive thin film, before plating treatment for forming a metal layer on the substrate sheet, at the time of plating In order to reduce the current flowing to the outer frame part of the base sheet , (1) Dot-shaped or mesh-shaped holes are formed so that the missing portions of the conductor thin film are scattered in the outer frame part over the entire circumference of the outer frame part. Or (2) providing a resist pattern on the conductor thin film in the product region and the outer frame portion, and a plurality of scattered circular resist film portions in the resist pattern in the outer frame portion; After the above (1) or (2), copper plating is applied to the product region and the outer frame of the base sheet, and the plating layer is formed in a dot shape, a mesh shape, or a circle in the outer frame portion. A base material sheet in which missing portions are scattered is formed, and thereafter, the outer frame portion is covered with a resist film, and gold plating is performed on a region where a gold plating layer in the product region is formed .

According to the above method, current can be collected in the product region during the copper plating process, and fine and precise current control for the product region is facilitated. Furthermore, the unstable action peculiar to the end of the outer frame part can be reduced. The copper plating film thickness can be finely adjusted according to the required specifications of the product, and high quality can be ensured. And for each product type, improve the accuracy of the copper plating thickness, it is possible to obtain a uniform copper plating film thickness for further product area.

Before the above copper plating treatment, one option is as follows: (1) For the base sheet having the outer frame portion in which the missing portions of the conductor layer are processed so that the missing portions are scattered in the outer frame portion. you a copper plating process Te. Thereby, while ensuring the strength and gripping portion of the outer frame portion, it is possible to reduce the amount of current flowing in and increase the ratio of the current flowing to the product region, thereby facilitating highly accurate current adjustment for the product region. In particular, the unstable action unique to the edge of a smooth (no hole) continuous plate is scattered over the missing part, so that the unstable action is averaged over the entire outer frame without concentrating on the edges or corners. And diluted. By averaging and diluting such unstable action, even if there is a slight deviation from the opposing metal plate facing, no significant effect occurs, and the accuracy of current control in the product area can be improved. As a result, the accuracy of the copper plating thickness in the product region can be improved and the thickness can be made uniform over the product region.

The conductor layer missing portion of the shall be the dot-like or mesh-like holes. Thereby, the accuracy of the current adjustment with respect to the product region can be enhanced by securing the strength of the outer frame portion and the gripping portion area by a simple processing such as punching. As a result, the accuracy of the copper plating thickness in the product region can be improved, and the copper plating thickness can be made uniform over the product region.

The case without the missing portion of the conductor layer, alternatively, prior to copper plating treatment, (2) setting the resist pattern Keru the product region and the outer frame portion of the conductor layer. In the product region surrounded by the outer frame portion, a resist pattern is always formed before the copper plating process in order to form a wiring circuit. By simultaneously forming the resist pattern in the product region and the resist pattern in the outer frame portion, there is no need to add a step of making a through hole in the outer frame portion by punching or the like. That is, the copper plating current does not flow in the resist film portion of the resist pattern of the outer frame portion, and the same effect as the missing portion of the conductor layer is achieved. As a result, it is possible to shorten the manufacturing period, save man-hours, and eliminate the need for a punching device. Overall, the manufacturing cost can be reduced as compared with punching or the like. Also, from the viewpoint of securing the strength of the outer frame portion, copper plating current control with a resist pattern is more preferable.
After the above copper plating treatment, before the gold plating treatment, the outer frame portion in which the portion without the copper plating layer is scattered is further covered with a resist film. That is, gold plating is performed on a region where the gold plating layer is formed in the product region (referred to as a gold plating layer forming region). The outer frame portion where the portions without the copper plating layer are scattered is further covered with a resist film. As a result, even in the gold plating process, the space occupation (presence) and strength as the outer frame portion are substantially maintained, and the gold plating current can be accurately controlled for the product area as in the copper plating process. it can.

When performing said plating process, as a reference example, the outer frame part mask which consists of an insulator can be provided in the apparatus of a plating process, or a base material sheet. As a result, it is possible to sufficiently control the current in the product area without applying processing that causes a change in shape or the like to the flexible printed wiring board sheet, and a plating film that is small in deviation from the intended thickness and uniform over the product area. Thickness can be obtained.

Although given as a reference example, in the outer frame portion, as located closer to the conductive portion from the cathode to the substrate sheet outer frame portion of the plating process, the above-mentioned (1), the area ratio of the conductive layer missing portion and large and small as the distance in the case of (2) above, by increasing the area ratio of the resist film portion Les resist pattern can a small to Turkey as the distance. Accordingly, the area ratio of the conductor layer missing portion that reduces the current density can be adjusted according to the current density over the position including the vicinity of the cathode conductive position of the outer frame portion and away from it. That is, when no measures are taken, in the vicinity of the cathode conductive position where the current density is very high, the area ratio of the missing portion is increased to reduce the current density, and the area ratio is decreased and the strength is ensured as the distance is further away. It can be important.

The flexible printed wiring board sheet to be used as a reference example is a flexible printed wiring board sheet including a plurality of flexible printed wiring boards including a plated metal layer. In this flexible printed wiring board sheet, an outer frame portion including a conductor layer is positioned so as to surround a product region where a plurality of flexible printed wiring boards are located. In the outer frame portion, (1) a missing portion is formed in the conductor layer. The copper plating layer is formed on the conductor layer that is scattered and not missing, or (2) has a copper plating layer on the conductor layer that does not include the missing portion, and the copper plating layer in the copper plating layer The copper plating layer lacking part which is missing is scattered. With this configuration, the current in the product region is finely controlled during the plating process, so that a uniform plating film thickness can be obtained with high accuracy. The missing portion in the copper plating layer is a portion covered with the resist film portion of the resist pattern during the copper plating process. The conductor layer is a conductor thin film that will be described later, and is a thin film of nickel, chromium, or the like having high adhesion to polyimide, and is formed by electroless plating or sputtering. For this reason, a conductor layer and a copper plating layer can be identified by the material and the thickness of the film.

  In the outer frame portion, a copper plating layer is formed on the non-hole portion of the conductor layer in which mesh-like or dot-like holes are formed, or a copper plating layer is formed on the conductor layer not including the missing portion, The structure which has a mesh-shaped or dot-shaped copper plating layer lacking part in a copper plating layer can be taken. As a result, the current in the product area can be controlled by simple processing such as punching or more efficient resist pattern formation, etc. to obtain a plating film thickness with less opportunity fluctuation and less place fluctuation at the same opportunity. Can do.

  The area ratio of the missing portion of the conductor layer and the copper plating layer, or the missing portion of the copper plating layer in the copper plating layer on the conductor layer not including the missing portion, is large at a predetermined location, and becomes smaller as the distance from the location increases. The structure formed can be taken. This makes it possible to increase the area ratio of the missing portion by aiming at a position where the current density becomes high and reduce the current density, and to reduce the area ratio of the missing portion as the distance from the position increases, and to ensure strength.

  According to the present invention, it is possible to obtain a flexible printed wiring board sheet and a method for producing the flexible printed wiring board sheet in which the current in the product region can be easily adjusted in the plating process in the manufacturing process of the flexible printed wiring board sheet having the outer frame portion.

(Embodiment 1)
FIG. 1 is a plan view showing a flexible printed wiring board sheet 50 according to Embodiment 1 of the present invention. In the following description, the flexible printed wiring board and the flexible printed wiring board sheet are abbreviated as FPC and FPC sheet, respectively. The entire FPC sheet 50 is rectangular, and an outer frame portion 5 is provided so as to surround a plurality of product regions 7 in which a plurality of FPCs 10 as final products are arranged. The FPC 10 is a magnetic head wiring board in which a supporting metal foil and a signal transmission wiring are integrated. The greatest feature of the FPC sheet 50 of the present embodiment is that circular holes, which are missing portions 5h, are scattered throughout the outer frame portion 5 surrounding the product region 7. The operation of the missing portion 5h provided in the outer frame portion 5 will be described sequentially thereafter.
In FIG. 1, the FPC sheet 50 is provided with a plating frame 21 that is conductive when plating. In FIG. 1, the wiring 11 of the FPC 10 is indicated by one thick line, but more specifically, as shown in FIG. 2, for example, three or more conductors are arranged in parallel. The wiring 11 is arranged so that the tip part is bent and the bent parts are opposed to form a pair. A plating lead portion 11 k is provided extending from the wiring 11, and the plating lead portion 11 k is connected to the plating frame 21. The wiring 11 / plating lead part 11k / plating frame 21 is located in the wiring layer which is the same layer (height, thickness direction position) in FIG. 1 and FIG.
In order to explain the subsequent plating process, a gold plating process region (G region) performed on the wiring 11 is introduced in advance.
(G region): In the G region, a gold plating layer is formed for connection to the wiring 11. The insulating cover layer 9 is located on the other wiring layer, but the insulating cover layer 9 is removed at the gold-plated portion for connection. In the G region, the stainless steel foil in the predetermined region is cut out.

Next, a method for manufacturing the FPC sheet 50 will be described. In the following description, an intermediate product of the FPC sheet 50 before completion is referred to as a base material sheet 50b.
FIG. 3A shows a state where a polyimide insulating layer 2 is formed on the stainless steel foil 1. The stainless steel foil 1 is used to elastically support a magnetic head (not shown) while slightly floating from the disk surface, and requires a predetermined elastic modulus.
Next, as shown in FIG. 3B, a conductor thin film 3 is formed on the polyimide layer 2 by electroless plating. The conductive thin film 3 becomes a base conductive layer for forming the wiring 11 by electroplating. Conventionally, a wiring of a copper plating layer or the like is formed on the conductive thin film 3 by electroplating as it is. That is, with respect to the intermediate product base sheet (a rectangular sheet formed from stainless steel foil 1 / polyimide layer 2 / conductor thin film 3), the wiring 11 / plating lead portion 11k is provided inside the product area 7, and the product area. A copper plating layer was formed like a crosspiece on the inner edge of the outer edge portion 7 and the outer frame portion 5.
In this copper plating process, a current is passed through the wiring 11 in the product region 7 to deposit copper ions as copper. However, since the conductor thin film 3 having a large area is immersed in the plating solution in the outer frame portion 5 as described above, a large current flows through the outer frame portion 5 in total. For this reason, the ratio of the current flowing into the product region 7 to the current flowing into the outer frame portion 5 becomes small. Also, the outer frame part in which the current to the edges and corners of the outer frame part of the flat plate without holes greatly changes due to a slight shift in the relative position with the metal plate (anode) on the other side facing the base sheet. There are also inherent instability effects. For this reason, there has been a problem that it is difficult to finely and accurately control the current flowing into the product region 7.

In order to overcome the above-described conventional problems, in the embodiment of the present invention, the entire circumference of the outer frame portion 5 of the base sheet (rectangular sheet formed of stainless steel foil 1 / polyimide layer 2 / conductor thin film 3) 50b. The circular holes 5h are punched out so as to be scattered. FIG. 4 is a plan view showing a state in which circular holes are punched out on the entire circumference of the outer frame portion 5 of the base sheet 50b. As a result, when the copper plating layers 11, 11 k, 21 are formed in the product region 7 on the conductor thin film 3, the current flowing into the outer frame portion 5 is greatly reduced, and the control of the current flowing into the product region 7 is finely increased. It can be accurate. In order to improve the accuracy of current control in this product area, the unstable action at the edges and corners of the outer frame of a completely flat plate without holes is averaged and diluted across the entire outer frame by scattered holes. That also contributes. Moreover, since the missing part 5h is not connected in the outer frame part 5 but scattered, the outer frame part 5 remains and has a predetermined strength. Therefore, it can function as a gripping part for handling, an alignment holding part for exposure using a reticle when forming a resist pattern, and the like.
Moreover, since the connection location conducted from the cathode during the plating process has a high plating current density, the proportion of the conductor thin film (conductor layer) missing portion 5h of the outer frame portion 5 is preferably increased in such a cathode conductive portion. The current density distribution can be averaged while placing importance on securing the strength of the outer frame portion 5 by reducing the proportion of the conductor layer missing portion as the distance from the cathode conductive portion increases.

FIG. 5 is a cross-sectional view showing the vicinity of the outer frame portion 5 in the copper plating process. FIG. 5A is a cross-sectional view of the vicinity of the outer frame portion 5 at the stage where the resist patterns R 1 and R 2 are formed in the product region 7. Copper plating layers 11, 11k, and 21 are formed in the openings of the resist pattern R1.
FIG.5 (b) is sectional drawing which shows the state which immersed the base material sheet 50b in the copper plating liquid (refer FIG. 9), and formed the copper plating layers 11, 11k, and 21. FIG. In the cross-sectional view of FIG. 5 (b), the cross-sectional length of the conductor thin film 3 of the outer frame portion 5 is halved, and the conductor thin film 3 is also greatly reduced in area. At this time, as shown in FIG. 5B, a copper plating layer 31 is formed on the conductor thin film 3 in the non-missing portion of the outer frame portion 5. The copper plating layer 31 remains on the shipped FPC sheet 50 and contributes to securing the strength. The missing part 5h provided in the outer frame part 5 significantly reduces the current flowing into the outer frame part 5 during the copper plating process. Therefore, the ratio of the current flowing into the product area 7 in the copper plating process is greatly increased. For this reason, the accuracy of current control for the product region 7 can be increased by changing the current value of the plating apparatus.
Thereby, it is possible to easily control the current value in the product area with a simple device. As a result, it has become easy to form a plating layer having an intended thickness accurately and uniformly. Conventionally, even if the current value of the plating apparatus is changed, the ratio of the product area is small, so that the current control for the product area 7 cannot be performed with high accuracy. For this reason, the case where the highly precise thickness plating layer was not obtained uniformly occurred. In the structure in which the lacking portion is opened in the conductor thin film 3 in the outer frame portion, when the plating solution is stirred, the liquid permeability becomes high, so that the effect of uniformizing the plating layer is also included.
In FIG. 5C, the resist patterns R1 and R2 are peeled off, and the copper plating layers 11, 11k, and 21 formed in the product region 7 by the plating process and the copper plating layer 31 formed in the outer frame portion 5 are formed. FIG.

FIG. 6 is a cross-sectional view of the vicinity of the outer frame portion 5 of the base sheet 50b when performing the gold plating process. In the product region 7 of the base sheet 50b, on the surface side, as shown in FIG. 6A, the G region is not covered with a cover insulating layer (not shown). The product region other than the G region is covered with a cover insulating layer. A resist pattern (not shown) is formed on the back surface of the stainless steel foil. In this state, it is immersed in a gold plating tank to perform a gold plating process (see FIG. 9). FIG. 6B is a diagram illustrating a state where the resist pattern is peeled after the gold plating layer 15 is formed. In the gold plating process, the outer frame portion 5 is covered with a resist film (not shown).
Even in the above gold plating process, the space occupancy (presence) and strength as the outer frame part 5 are substantially maintained by interspersing the missing part 5h in the outer frame part 5, and, similarly to the copper plating process, The plating current for the product region 7 can be accurately controlled.

  FIG. 7 is a diagram illustrating a modification of the FPC sheet according to the present embodiment. In the FPC sheet 50 shown in FIG. 1, the missing portion 5 h in the outer frame portion 5 is a punched circular hole. In the modification of FIG. 7, the outer frame portion 5 has a lattice shape, and a square hole is the missing portion 5 h. The only difference is that the circular hole in FIGS. 1 and 4 is a square hole, and the above description can be used as it is for the manufacturing method and effects.

(Embodiment 2)
FIG. 8 is a diagram for explaining a method for manufacturing a flexible printed wiring board sheet according to Embodiment 2 of the present invention. The manufacturing method according to the present embodiment is characterized in that a through hole is not provided in the outer frame portion 5 of the base sheet, and high-precision control of the plating current is realized by the resist pattern R1. The manufacturing method is roughly as follows.
(S1) A polyimide layer 2 is formed on the stainless steel foil 1, and a conductive thin film 3 is formed on the polyimide layer 2. As described above, the conductive thin film 3 is preferably formed of nickel, chromium, or the like having high adhesion to polyimide, and is formed by electroless plating or sputtering.
(S2) As shown in FIG. 8A, a resist pattern R1 is formed on the product region 7 and the outer frame portion 5 at the same opportunity. The resist pattern R1 of the outer frame portion 5 has, for example, a resist film portion in which a plurality of circles, squares, and the like are scattered.
(S3) A copper plating process is applied to the base material sheet. Since the resist film portion of the resist pattern R1 is an insulator and no plating current flows, the same effect as the missing portion 5h of the conductor layer 3 in the first embodiment is obtained. For this reason, the electric current which flows into the outer frame part 5 can be reduced. However, at this time, as shown in FIG. 8B, the copper plating layer 31 is formed in the resist pattern opening.
(S4) As shown in FIG. 8C, the resist pattern is removed. As a result, the copper plating layer 31 from which the plurality of circles, squares, and the like are missing remains in the outer frame portion 5. That is, the copper plating layer 31 remains on the product of the FPC sheet at the time of shipment.

In the product region surrounded by the outer frame portion, a resist pattern is always formed before plating in order to form a wiring circuit. By simultaneously forming the resist pattern in the product region and the resist pattern in the outer frame portion, there is no need to add a step of making a through hole in the outer frame portion by punching or the like. That is, the plating current does not flow in the resist film portion of the resist pattern in the outer frame portion, and has the same effect as the missing portion of the conductor layer. As a result, it is possible to shorten the manufacturing period, save man-hours, and eliminate the need for a punching device. Overall, the manufacturing cost can be reduced as compared with punching or the like. Moreover, the conductor thin film 3 that does not include the missing portion and the copper plating layer that surrounds the missing portion are useful for securing the strength in the outer frame portion.
Further, according to the above manufacturing method, as in the first embodiment, the current flowing into the outer frame portion 5 can be greatly reduced, and the control of the current flowing into the product region 7 can be finely and accurately performed. Since the connection location conducted from the cathode during the plating process has a high current density, the ratio of the resist film portion of the resist pattern R1 of the outer frame portion 5 is preferably increased in such a cathode conductive portion. The current density distribution of the outer frame portion 5 can be averaged by decreasing the ratio of the resist film portion as the distance from the cathode conductive portion increases.

(Embodiment 3 given as a reference example )
FIG. 9 is a diagram illustrating a plating apparatus 70 according to Embodiment 3 which is cited as a reference example . A plating solution 75 is charged into the plating tank 77, and the base sheet 50 b is disposed in the plating solution 75. A wiring 72 from a cathode (not shown) is connected to the plating frame 21 of the base sheet 50b. In addition, a metal plate 71 a connected to the anode wiring 71 is disposed facing the base sheet 50 b. The metal plate 71a is a copper plate in the case of copper plating, and a gold plate or the like is used in the case of gold plating. In FIG. 9, the outer frame portion of the base sheet 50b is covered with an outer frame mask 81 formed of an insulator. FIG. 10 is a perspective view showing the outer frame mask 81. The outer frame portion mask 81 is attached to the base material sheet 50b by a clip 83 and covers the outer frame portion of the base material sheet 50b.

According to FIG. 9, only the product region 7 of the base sheet 50 b is in contact with the plating solution 75. Since the outer frame portion mask 81 is an insulator, when it is attached to the base sheet 50b as shown in FIG. 9, the current flowing into the outer frame portion 5 becomes very small. For this reason, most of the current flowing between the cathode and the anode flows in the product region 7. As a result, the current value of the product region 7 can be accurately controlled by using the current control unit provided in the apparatus. As a result, a plating layer having a uniform thickness can be obtained with a high-precision thickness as intended. As in the first embodiment, the outer frame portion 5 of the base sheet 50b may be provided with the missing portion 5h of the conductor layer 3, or may be the base sheet 50b without the missing portion.
Further, since the current density is high at a portion that is conductive from the cathode during the plating process (connection portion of the wiring 72), the coverage of the mask 81 of the outer frame portion 5 is preferably increased in such a cathode conductive portion. The current density distribution can be averaged by reducing the coverage of the mask 81 as the distance from the cathode conductive portion increases.

  Although the embodiments and examples of the present invention have been described above, the embodiments and examples of the present invention disclosed above are merely examples, and the scope of the present invention is the implementation of these inventions. It is not limited to the form. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  ADVANTAGE OF THE INVENTION According to this invention, the controllability of the electric current value to a product area | region can be improved in a plating process, after ensuring the ease of handling of a base material sheet. As a result, it is possible to improve the film thickness accuracy of the plating layer in the product region and to ensure uniformity.

It is a top view which shows the FPC sheet in Embodiment 1 of this invention. It is the elements on larger scale of the wiring part in FPC of FIG. It is sectional drawing of a base material sheet, (a) is a figure which shows the state which formed the polyimide layer on the stainless steel foil, and (b) is the figure which formed the conductive thin film on it. It is a figure which shows the state after performing the process which makes the missing part of a conductor layer interspersed in the outer frame part of the base material sheet of the state of FIG.3 (b). It is sectional drawing of the outer frame part vicinity of a base material sheet, (a) is the state which performed the patterning process to the resist film, (b) is the state which formed wiring by the copper plating process, (c) is the resist film It is a figure which shows the state which peeled. (A) is a figure which shows the state before a gold plating process, (b) shows the state after performing a gold plating process. It is a top view which shows the FPC sheet of the modification of Embodiment 1 of this invention. It is a figure which shows the manufacturing method of the FPC sheet in Embodiment 2 of this invention, (a) is the state which formed the resist pattern in the product area and the outer frame part on the same occasion, (b) is the state which carried out the copper plating process, (C) is a figure which shows the state which peeled the resist pattern. It is a figure for demonstrating the manufacturing method of the FPC sheet in Embodiment 3 of a reference example . It is a figure which shows an outer frame part mask.

DESCRIPTION OF SYMBOLS 1 Stainless steel foil, 2 Polyimide layer (insulating layer), 3 Conductor thin film, 5 Outer frame part, 5h Conductor layer missing part of outer frame part, 7 Product area, 9 Cover insulating layer, 10 Flexible printed wiring board (FPC), 11 Wiring, 11k plating lead part, 15 gold plating layer, 21 plating frame, 31 copper plating layer of outer frame part, 50 FPC sheet (flexible printed wiring board sheet), 50b base sheet (intermediate product), 70 plating processing apparatus, 71 anode wiring, 71a metal plate (copper plate, gold plate), 72 cathode wiring, 75 plating solution, 77 plating tank, 81 outer frame mask, 83 clip.

Claims (1)

A method for producing a flexible printed wiring board sheet comprising a plurality of flexible printed wiring boards including a plated metal layer,
The flexible printed wiring board sheet has an outer frame part over the entire circumference, and a product region surrounded by the outer frame part to form the flexible printed wiring board,
Forming a base sheet that is an intermediate product of the flexible printed wiring board sheet including stainless foil / insulating film / conductor thin film in common for the outer frame portion and the product area ;
Before copper plating treatment to form a copper plating layer on the base sheet,
In order to reduce the current flowing to the outer frame portion of the base sheet during the copper plating process, over the entire circumference of the outer frame portion,
(1) Dot-shaped or mesh-shaped holes are provided by processing so that the missing portions of the conductive thin film are scattered in the outer frame portion, or
(2) A resist pattern is provided on the conductor thin film in the product region and the outer frame portion, and the resist film portion in the resist pattern of the outer frame portion is a plurality of scattered circles, squares, and the like,
After said (1) or (2), a copper plating process is performed to the product area | region and outer frame part of the said base material sheet, and a copper plating layer is formed in the said outer frame part in dot shape, mesh shape, or a circle | round | yen Forming a base material sheet with scattered parts,
A method for manufacturing a flexible printed wiring board sheet, wherein the outer frame portion is covered with a resist film, and gold plating is performed on a region where a gold plating layer is formed in the product region .

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