JP2008034433A - Manufacturing method of rigid flex printed wiring board and rigid flex printed wiring board - Google Patents

Abstract

The present invention provides a rigid flex printed wiring board in which a bent portion of a rigid flex printed wiring board is small and formed with high positional accuracy.
A step of forming a circuit on both surfaces of a first substrate to be a core material and then laminating an insulating material, and a second and a third substrate are laminated so as to sandwich the first substrate having a circuit formed on both surfaces. A step of forming the circuits of the second and third substrates leaving a copper solid larger than a portion to be bent later, a step of laminating the prepreg and the copper foil, and a copper foil in a portion to be bent later A step of forming an opening, a bending portion forming step of irradiating the copper foil opening with a laser to expose the solid copper of the second and third substrates in the bent portion, desmear treatment and copper plating And a step of removing the copper foil and the copper plating at the bent portion by etching and forming an outer layer circuit by etching.
[Selection] Figure 2

Description

  The present invention relates to a manufacturing method of a rigid flex printed wiring board and a rigid flex printed wiring board, and in particular, a rigid flex printed wiring board capable of forming a bent portion (flexible window portion) of the rigid flex printed wiring board with a small size and high positional accuracy. And a rigid flex printed wiring board in which the bent portion is small and formed with high positional accuracy.

  The rigid-flex printed wiring board is composed of a hard portion having hardness and strength that can withstand the weight of a component to be mounted, and can be fixed to a housing, and a bent portion that can be bent.

  In addition, the conventional rigid-flex printed wiring board forms a flex circuit, and after laminating the coverlay, the bent portion is formed by laminating a low-flow prepreg provided with an opening so that the bent portion is exposed in advance. It was.

  However, even in the case of a low flow prepreg, the resin flows out slightly in the lamination, so that the length of the bent portion needs to be a certain value or more. In addition, when the low-flow prepreg lamination is pin lamination, the opening of the bent portion is aligned by the pin, and in the case of mass lamination, alignment is performed by eyelet or fusion, so that the positional accuracy is limited. There was a problem.

  In addition, a method for producing a rigid flex printed wiring board using a prepreg having a resin flow of 8 to 16% for adhesion between a bent portion and a hard portion has already been reported (for example, see Patent Document 1).

However, even with this method, since the resin flows out when the prepreg is laminated, there is a problem that the bent portion must be set longer in consideration of the amount of the resin flowing out. Further, since the flow of the resin also changes depending on the lamination conditions and the plate thickness, the actual condition is that the bent portion could not be formed with high accuracy.
JP-A-6-334278

  In view of the above-mentioned problems and actual circumstances, the present invention provides a method for manufacturing a rigid flex printed wiring board that can be formed with high accuracy and a small bending portion of a rigid flex printed wiring board, and the bending portion is small and has high positional accuracy. It is an object of the present invention to provide a rigid flex printed wiring board formed in the above.

  In order to solve the above problems, the present invention according to claim 1 is a method of manufacturing a rigid flex printed wiring board, comprising: forming a circuit on both surfaces of a first substrate as a core material; The second and third substrates are laminated so as to sandwich the first substrate on which the circuit is formed, and the circuits of the second and third substrates are formed leaving a copper solid larger than the portion that will later become the bent portion. A step of laminating a prepreg and a copper foil, a step of forming a copper foil opening in a portion that will later become a bent portion, and irradiating the copper foil opening with a laser so that the second and second portions in the bent portion A step of forming a bent portion for exposing the solid copper of the substrate 3 and a step of performing desmearing treatment and copper plating, removing the copper foil and the copper plating of the bent portion by etching, and forming an outer layer circuit by etching. Have It is characterized by a door.

  Thereby, the bending part of a rigid flex printed wiring board can be formed small, and with sufficient position accuracy.

  Further, the present invention according to claim 2 is characterized in that the step of forming the copper foil opening at a portion that will later become a bent portion is performed by window etching.

  The present invention according to claim 3 is characterized in that the non-through hole is formed simultaneously with the bending portion forming step by laser irradiation.

  According to a fourth aspect of the present invention, there is provided a rigid body having a flexible bending portion that can be bent, and a hard portion that can withstand the weight of a component to be mounted and that can be fixed to a housing and has strength and strength. The flex printed wiring board is characterized in that a bent portion is small and formed with high positional accuracy.

According to the present invention, since the bent portion is formed by a laser, the width of the bent portion can be reduced without being limited by the flow amount of the resin.
In addition, since the resin in the adhesive layer is removed at the same time that the bent portion is formed by a laser, and no excess resin protrudes into the bent portion, the positional accuracy of the bent portion is adjusted to the alignment accuracy of the inner layer / outer layer circuit (for example, ± 100 μm or less). Can be raised to the same level.

Furthermore, since ordinary prepregs can be used, there are more choices of materials, reducing material costs,
The outer layer pattern can be flattened.
Furthermore, in the past, when a thin copper foil was used while the copper foil on the bent portion was lifted up, it was sometimes broken in the middle of the process. However, in the method of the present invention, the copper foil does not float, so a thin copper foil is used. Or a half-etching process can be easily performed.

  Hereinafter, the best embodiment of the present invention will be described with reference to the drawings. In addition, this invention is not restrict | limited at all by embodiment described in full detail below, A various change is possible within the scope of the present invention.

  1 to 3 are schematic cross-sectional process explanatory views showing a method of manufacturing a rigid flex printed wiring board according to the present invention. 1-3, 101 is a flexible circuit, 102a and 102b are resin-coated copper foils, 103a and 103b are solid copper, 104a to 104d are circuits of the second layer L2, and 105a to 105d are Circuits of the fifth layer L5, 106a and 106b are prepregs, 107a and 107b are copper foils, 108a to 108c are circuits of the first layer L1, 109a to 109c are circuits of the sixth layer L6, 110a, 110b, 111a, 111b is an outer layer.

  First, as shown in FIG. 1A, a flexible circuit 101 composed of a third layer L3 and a fourth layer L4 is formed, and then flexible resin-coated copper foils 102a and 102b are used instead of the coverlay. Are laminated.

The flexible circuit 101 composed of the third layer L3 and the fourth layer L4 corresponds to a circuit formed on both surfaces of a flexible first substrate serving as a core material. The flexible resin-coated copper foils 102a and 102b correspond to laminated flexible insulating materials, and instead of the resin-coated copper foils 102a and 102b, an adhesive sheet and copper foil are used. Is also possible.
Furthermore, it is also possible to use copper plating or printing instead of the copper foil. It is also possible to form a conductive paste or the like by screen printing.

Next, as shown in FIG. 1B, the second layer L2 circuits 104a to 104d, 103a and the fifth layer L2, while leaving the copper solids 103a, 103b that are slightly larger than the bent portions A later, Circuits 105a to 105d and 103b of the layer L5 are formed.
The circuits 104a to 104d and 103a in the second layer L2 and the circuits 105a to 105d and 103b in the fifth layer L5 correspond to circuits formed on the second and third substrates, respectively.

  Next, as shown in FIG. 1C, prepregs 106a and 106b and copper foils 107a and 107b are laminated. The prepregs 106a and 106b are, for example, glass cloth impregnated with an epoxy resin, but are not required until the opening of the bent portion A is formed. In addition, it is not always necessary to perform alignment with a pinami, and a so-called massami may be used. Furthermore, an ordinary prepreg can be used instead of the low flow prepreg.

  Next, as shown in FIG. 2 (d), the copper foils 107a and 107b at the bent portions A are simultaneously removed by etching to remove the copper foils 107a and 107b at the non-through-hole (Blind Via Hole) forming portions. The copper foil openings 107a ′ and 107b ′ and 107a ″ and 107b ″ are formed by removing the copper foil openings 107a ′ and 107b ′ and 107a ″ and 107b ″. This process is called a window etching process. In addition, in this invention, the other method of removing copper foil can also be used without being limited to such a window etching process.

  Next, as shown in FIG. 2E, the copper foil openings 107a ′, 107b ′ and 107a ″, 107b ″ to be the bent portion A are irradiated with laser, and the second layer L2 and the second layer L2 in the bent portion A are irradiated. The three-layer L3 copper solids 103a and 103b are exposed. This step is called a bent portion forming step. The second layer L2 and the third layer L3 correspond to a second substrate and a third substrate, respectively.

  In the present invention, the non-through holes 108 ′ and 109 ′ can be formed by irradiating a laser simultaneously with the formation of the bent portion A by the laser irradiation. That is, the step of forming the non-through holes 108 ′ and 109 ′ by irradiating the laser, and the bending portions A by irradiating the copper foil openings 107 a ′, 107 b ′ and 107 a ″, 107 b ″ to be the bent portions A with laser. The step of exposing the copper solids 103a, 103b of the second layer L2 and the third layer L3 in the step can be performed simultaneously in one step.

Next, as shown in FIG. 3 (f), after desmearing and copper plating are performed, the copper foil and copper plating at the bent portion A are removed by etching. This process is called a window opening etching process.
Next, an outer layer circuit is formed by etching. Note that the formation of the outer layer circuit is not limited to the case where the outer layer circuit is formed as a subsequent process of the window opening etching process, but can be performed in one etching process simultaneously with the window opening etching process.

  That is, after the desmear process and the copper plating, the outer layer circuit may be formed simultaneously with the removal of the copper foil and the copper plating of the bent portion A by etching.

In this way, a rigid flex printed wiring board is manufactured that has higher positional accuracy than the conventional one and can thereby narrow the bent portion A.
That is, since the rigid flex printed wiring board is manufactured as described above, the resin of the adhesive layer is removed in the subsequent process of forming the bent portion A, and the excess resin does not protrude from the bent portion. Therefore, the bent portion can be formed with high positional accuracy, and the width of the bent portion A can be reduced.

  On the other hand, FIG. 4 is a schematic cross-sectional explanatory view of the rigid flex printed wiring board of the present invention. In FIG. 4, A is a bent portion of a flexible printed wiring board that can be bent, and B1 and B2 are printed wiring boards that can withstand the weight of components to be mounted, and have hardness and strength that can be fixed to a housing. The hard part.

  In addition, 201 is a flexible circuit composed of the third layer L3 and the fourth layer L4, 202a and 202b are copper foils with a flexible resin, 206a and 206b are prepregs made by impregnating an epoxy resin into a glass cloth, for example, 208a ˜208c is a circuit made of the first layer L1, 209a to 209c are circuits made of the sixth layer L6, and 210a, 210b and 211a, 211b are outer layers.

  The rigid flex printed wiring board of the present invention having such a structure has a bending portion A having a bendable flexibility and the weight and strength of a component to be mounted and can be fixed to the housing. The hard portions B1 and B2 that are included are integrated by lamination.

  Further, the bent portion A is small and formed with high positional accuracy.

  In addition, the lamination may be any of a lamination press using an autoclave press, a lamination press using a hot plate, a lamination to be thermally cured after lamination, a lamination to be laminated after printing, and a lamination to which plating is directly attached after printing. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 2 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 1. FIG. 3 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 2. The schematic cross-section explanatory drawing of the rigid flex printed wiring board of this invention.

Explanation of symbols

101: Flexible circuit 102a, 102b: Resin copper foil 103a, 103b: Solid copper 104a-104d: Second layer L2 circuit 105a-105d: Fifth layer L5 circuit 106a, 106b: Prepreg 107a, 107b: Copper foil A: Bending parts B1, B2: Hard part 201: Flexible circuit 202a, 202b composed of the third layer L3 and the fourth layer L4: Copper foils 206a, 206b with flexible resin: Pre-preg,
208a to 208c: Circuits 209a to 209c composed of the first layer L1: Circuits 210a, 210b, 211a and 211b composed of the sixth layer L6: Outer layer

Claims (4)

Forming an insulating material after forming circuits on both surfaces of the first substrate as a core material;
The second and third substrates are stacked so as to sandwich the first substrate on which the circuits are formed on both sides, and the second and third substrate circuits are formed, leaving a copper solid that is larger than the portion that later becomes the bent portion. And a process of
Laminating prepreg and copper foil;
A step of forming a copper foil opening in a portion that later becomes a bent portion;
A bending portion forming step of irradiating the copper foil opening with a laser to expose the copper solids of the second and third substrates in the bending portion;
A method for manufacturing a rigid flex printed wiring board, comprising: performing desmearing and copper plating, and removing the copper foil and copper plating of the bent portion by etching and forming an outer layer circuit by etching.   2. The method of manufacturing a rigid flex printed wiring board according to claim 1, wherein the step of forming a copper foil opening in a portion that will later become a bent portion is performed by window etching.   3. The method of manufacturing a rigid flex printed wiring board according to claim 1, wherein the non-through hole is formed simultaneously with the bent portion forming step by laser irradiation.   In a rigid flex printed wiring board having a bent portion having flexibility that can be bent and a hard portion having a hardness and strength that can withstand the weight of the mounted component and can be fixed to the housing, the bent portion is small, A rigid flex printed wiring board characterized by being formed with high positional accuracy.