JP2006140213A - Rigid flexible multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rigid flexible multilayer printed wiring board where connection reliability of a through hole can be secured even if a flexible board does not exist in the rigid part or the end part of the flexible board is included in a region of the rigid part. <P>SOLUTION: The rigid flexible multilayer printed wiring board is provided with the core substrate of the rigid part, the flexible board arranged adjacently to the horizontal direction of the core board, an insulating adhesive layer which is laminated on the surface and the rear face of the core board and the flexible board and has flexibility after curing, a wiring pattern which is positioned in the rigid part and is formed on the insulating adhesive layer having flexibility, and a blind via hole and/or the through hole which connect the wiring patterns formed in the respective layers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rigid-flex multilayer printed wiring board, and more particularly to a thin rigid-flex multilayer printed wiring board excellent in connection reliability of blind via holes and / or through-holes connecting wiring pattern forming layers.

  The configuration of a conventional rigid flex multilayer printed wiring board will be briefly described.

  FIG. 3 shows a four-layer rigid-flex multilayer printed wiring board Pb, a flexible substrate 1 on which a wiring pattern 2 is formed, a coverlay 3 laminated to protect the wiring pattern 2, and a flex portion. Insulating adhesive sheet 4 laminated in a portion excluding F, wiring pattern 2 formed on insulating insulating sheet 4, through hole 5 connecting between wiring patterns 2 formed in each layer, and outer layer wiring The solder resist 6 for protecting the pattern 2 is provided.

  However, the configuration of the rigid flex multilayer printed wiring board Pb has the following problems.

  That is, since the flexible substrate 1 is easily expanded and contracted, it is difficult to align the through holes 6 and it is difficult to achieve high-density wiring.

  Therefore, as a solution to such a problem, a rigid-flex multilayer printed wiring board Pa configured as shown in FIG. 4 is known (see Patent Document 1).

  The rigid-flex multilayer printed wiring board Pa includes a flexible substrate 1 disposed in a portion corresponding to the flex portion F, an insulating adhesive sheet 4 disposed adjacent to the flexible substrate 1 in the horizontal direction, and the adjacent A wiring pattern 2 formed on the front and back of the flexible substrate 1 and the insulating adhesive sheet 4 disposed; a coverlay 3 laminated on the front and back of the flexible substrate 1 on which the wiring pattern 2 is formed; and a flex The insulating adhesive sheet 4 laminated on the portion excluding the part F, the outer layer wiring pattern 2 formed on the insulating adhesive sheet 4, and the through hole 5 connecting between the wiring patterns 2 formed on each layer, A solder resist 6 for protecting the outer layer wiring pattern 2 is provided.

  As described above, the flexible substrate 1 does not exist in the rigid portion R, or the end portion of the flexible substrate 1 is slightly included in the region of the rigid portion R, thereby aligning the through hole 7 and the wiring pattern 2. It can be improved.

  However, in the configuration of the rigid-flex multilayer printed wiring board Pa, the coverlay 3 is laminated on the front and back as a means for integrating the flexible substrate 1 and the insulating adhesive sheet 4 disposed adjacent to the flexible substrate 1. Since they are integrated with each other (including the rigid portion R), there are the following problems.

That is, the cover lay 3 has a two-layer structure in which an epoxy or acrylic adhesive (not shown) is applied to the surface of a polyimide resin, and an adhesive having a low Tg (glass transition point) characteristic is interposed. Therefore, the connection reliability of the through hole is reduced.
JP-A-7-94835

  The present invention has been made in order to solve the above-described problems, and even when the flexible substrate is not present in the rigid portion or the end portion of the flexible substrate is slightly included in the region of the rigid portion, It is an object of the present invention to provide a rigid-flex multilayer printed wiring board that can ensure connection reliability.

  The present invention is a rigid flex multilayer printed wiring board having a rigid portion and a flex portion, at least a core substrate of the rigid portion, a flexible substrate disposed adjacent to the horizontal direction of the core substrate, and the Insulating adhesive layer having flexibility even after curing laminated on the front and back of the core substrate and the flexible substrate, a wiring pattern formed on the insulating adhesive layer having flexibility and located in the rigid portion, and each layer The above-mentioned problems are solved by a rigid-flex multilayer printed wiring board characterized by having blind via holes and / or through-holes connecting the formed wiring patterns.

  Since the flexible substrate and the rigid core substrate are integrated with a flexible insulating adhesive layer even after curing, the connection reliability of the through hole can be improved. In addition, since the insulating adhesive layer having flexibility is used as a structure that combines the coverlay of the flexible substrate and the function of the insulating adhesive sheet when multilayered, the rigid flex multilayer printed wiring board can be thinned. it can.

  Hereinafter, an embodiment of the rigid flex multilayer printed wiring board of the present invention will be described with reference to FIG. In addition, the same code | symbol was attached | subjected to the site | part same as a prior art.

  FIG. 1 (e) shows a schematic cross-sectional view of the rigid-flex multilayer printed wiring board P according to the present invention. The multilayer printed wiring board P includes the core substrate 7 of the rigid part R and the horizontal of the core substrate 7. Flexible substrate 1 arranged adjacent to the direction, core substrate 7 and inner layer wiring pattern 2 formed on flexible substrate 1, and flexible insulation laminated on the front and back of core substrate 7 and flexible substrate 1 An adhesive layer 9; an outer layer wiring pattern 2 formed on the flexible insulating adhesive layer 9 located in the rigid portion R; a through hole 5 connecting between the wiring patterns 2 of each layer; A blind via hole 14 for connecting the wiring pattern 2 and the wiring pattern 2 formed in the rigid portion, and a solder resist 6 for protecting the wiring pattern 2 on the outer layer. It is formed in a substantially flat and rigid section R and the flex portion F.

  Next, a method for producing such a rigid flex multilayer printed wiring board of the present invention will be described with reference to FIGS.

  First, the wiring pattern 2 is formed on the front and back of the insulating base material by a general subtractive method or additive method, and then the opening 8 is formed at a portion where a flexible substrate is disposed later by a router, a mold, or the like. As a result, the core substrate 7 shown in FIGS. 1A and 2 is obtained.

  Next, a flexible substrate 1 having a size corresponding to the opening 8 (wiring pattern 2 already formed) is prepared, and the flexible substrate 1 is arranged in the opening 8 as shown in FIGS. To do.

  Next, on the front and back of the core substrate 7 and the flexible substrate 1, a flexible insulating adhesive layer 9 and a metal foil 10 having flexibility even after curing are sequentially laminated, or a resin-attached metal in which both are laminated in advance. The substrate in the state shown in FIG. 1B is obtained by arranging the foil (see FIGS. 1A and 2) and then performing a lamination press.

  Next, as shown in FIG. 1 (c), the non-through hole 11 and the through hole 12 are drilled in the portion where the interlayer connection is performed, and then the desmear process of the non-through hole 11 and the through hole 12 is performed. After that, the plating 13 is formed on the entire surface (see FIG. 1D).

  Next, after forming the wiring pattern 2 in the outer layer and the blind via hole 14 and the through hole 5 by a general subtractive method, and then forming the solder resist 6 for protecting the wiring pattern 2 in the outer layer The rigid-flex multilayer printed wiring board P having a configuration in which the flexible substrate 1 of the flex portion F does not exist in the rigid portion R or the end portion of the flexible substrate 1 is slightly included in the region of the rigid portion R by performing the outer shape processing. (See FIG. 1 (e)).

  In the description of the present invention, a four-layer rigid-flex multilayer printed wiring board has been described as an example. However, the configuration of the present invention is not limited to this, and the present invention works effectively with a layer configuration beyond this.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 2 is an exploded perspective view of the laminate shown in FIG. Schematic cross-sectional explanatory drawing of the conventional rigid flex multilayer printed wiring board. Schematic cross-sectional explanatory drawing of the other conventional rigid-flex multilayer printed wiring board.

Explanation of symbols

1: flexible substrate 2: wiring pattern 3: coverlay 4: insulating adhesive sheet 5: through hole 6: solder resist 7: core substrate 8: opening 9: flexible insulating adhesive layer
10: Metal foil
11: Non-through hole
12: Through hole
13: Plating
14: Blind via hole P, Pa, Pb: Rigid flex multilayer printed wiring board

Claims (1)

  A rigid-flex multilayer printed wiring board having a rigid portion and a flex portion, at least a core substrate of the rigid portion, a flexible substrate disposed adjacent to the core substrate in the horizontal direction, and the core substrate and the flexible substrate Insulating adhesive layer having flexibility even after curing laminated on the front and back of the substrate, a wiring pattern formed on the insulating adhesive layer having flexibility and located in the rigid portion, and wiring formed in each layer A rigid-flex multilayer printed wiring board having blind via holes and / or through-holes connecting between patterns.

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