JPS59232491A - Method of producing multilayer printed circuit board - 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 [Technical Field] The present invention relates to a method for manufacturing a multilayer printed wiring board.

[Background technology]

Conventionally, when forming multilayer wiring on a printed wiring board, a wiring pattern (9
) is formed on the wiring board (2) through-hole (3)
There is a silver jumper method, etc. in which an insulating resin (10) with perforated holes is applied and a silver paste (■) is printed on the surface of the insulating resin (10).
Since it is applied by printing, it lacks reliability, and silver paint (printing) has the disadvantage of not being able to handle high-density wiring.
) The copper through-hole method, in which copper plating 021 is applied to the through-hole (3) part, has the disadvantage that it requires equipment for electroless copper plating and electroplating, and is expensive. .

[Purpose of the invention]

The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board that allows multilayer wiring to be easily formed, has high reliability, and can be manufactured at low cost. This is the purpose.

[Disclosure of the invention]

That is, in the present invention, a first wiring pattern (1) is formed on the surface of a wiring board (2), and then the surface of the wiring board (2) is heated to a temperature higher than the softening temperature of the resin. is applied to connect the first wiring pattern t1+ to the wiring board (
2) to make the surface of the wiring board (2) smooth, and then an electric wire layered metal foil (4) with through holes (31) is buried on the wiring board (2). ) are on the surface side, and align the through holes (31 with the first wiring butter, 7 f11), and then apply the protective layer (6) on the surface of the metal foil (5).
L, - Apply the second wiring butter in a pattern shape to cover the hole (3), and then apply the second wiring butter to the metal foil (5) by etching.
/ +71 is formed, and after removing the protective layer (6), the through hole (3) is filled with a conductive material (8) and the first
The above object has been achieved by a method for manufacturing a multilayer printed wiring board, which is characterized in that the distribution pattern i11 of the second wiring pattern (7) is electrically connected to the second wiring pattern (7).

The present invention will be explained in detail below. Although the wiring board (2) is not limited in any way, for example, a metal base board, a resin board, a plastic board, a single-sided board, a double-sided board, a double-sided through-hole board, etc. thereof can be used. The front and back surfaces of this wiring board (2) are shown in Figure 3 (a).
), the first wiring pattern il+ is formed. This wiring board [21] is heated to a temperature higher than the softening temperature of its resin, and in that state, the surface of the wiring board (2) is pressure-molded to embed the wiring pattern fi+ in the distribution board (2) (Fig. ) ). This is what is called flash molding, and after this heating, an electrically insulating layer with through holes (3) drilled on the wiring board (2) as shown in FIG. 3(C). The attached metal foil (4) is stacked and integrated so that the metal foil (5) is on the front side, and the through hole (3) is aligned with the first wiring pattern (1+ position.Here, the electrical insulating layer 03
As No. 1, it can be formed by a resin coating layer or a resin coating layer. Next, a protective layer (6) is applied to the surface of the metal foil (5) in a patterned manner so as to cover the through holes (3) (FIG. 4(d)). The protective layer (6) may be formed by applying an etching resist, or may be formed by tenting using a thermoplastic film. If an etching resist is used at this time, the through holes (31) are also filled in. Next, the second wiring pattern (7) is etched on the metal foil (5).
After that, the surface of the metal foil (5) and the through hole (
3) to remove the protective layer (6) in the same figure (e), and then fill the through hole (3) with a conductive material (8) such as solder or conductive paste to form the first wiring pattern il+ and the first wiring pattern il+. The second wiring pattern (7) is electrically connected to the second wiring pattern (7). 05) in the figure is an electric wire RIM.

Then, a protective layer (6) is applied to the surface of the metal foil (5) in a patterned manner so as to cover the through holes (3), and a second wiring pattern (7) is formed on the metal foil (5) by etching. After removing the protective layer (6), the conductive material (8) is filled in the through hole (31) to electrically connect the first wiring pattern il+ and the second wiring J\ turn (7). By making connections, multilayer wiring can be easily formed regardless of the type of wiring board (2). ) is directly filled into the hole (31) for connection, so it has the same reliability as the copper through-hole method, and can be manufactured at a low cost without the need for plating equipment. Then, the wiring pattern of item 1 + 11 is buried in the wiring board (21) to form the wiring board (2).
By making the surface smooth, it becomes easier to apply etching resist, a highly accurate wiring pattern (7) can be formed, and the reliability when mounting electronic components is also increased. Furthermore, the metal foil after the second layer (
5) Since the surface can be made smooth, it is easy to manufacture a high multilayer wiring board and the reliability can be improved. In the above embodiment, the multilayer wiring pattern +71 [71] was formed on both sides of the wiring board (2), but the wiring pattern (7) may be formed on one side.

〔Effect of the invention〕

As described above, in the present invention, metal foils with electrically insulating layers having through-holes are stacked on a wiring board having a first wiring pattern formed on the surface thereof, with the metal foils facing toward the front surface. At the same time, the through holes are aligned with the first wiring pattern position, and then a protective layer is applied to the surface of the metal foil in a pattern shape so as to cover the through holes, and a second wiring pattern is formed on the gold layer foil by etching. Then, after removing the protective layer, the through holes were filled with conductive material to electrically connect the first wiring pattern and the second wiring pattern, making multilayer wiring easy regardless of the type of wiring board. It is highly reliable, and can be manufactured at low cost. In addition, a first wiring J is formed on the surface of the wiring board.
After forming the turn, the surface of the wiring board was heated to a temperature higher than the softening temperature of the resin, and the wiring pattern was buried in the wiring board by pressing the surface of the wiring board to make the surface of the wiring board smooth. It has high reliability and printing accuracy, making it possible to form precise wiring patterns.It also increases the reliability of component mounting, and makes it easier to manufacture high multilayer printed wiring boards, increasing reliability. It is possible.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway sectional view of a conventional example, FIG. 2 is a partially cutaway sectional view of another conventional example, and FIGS. FIG. +11 is the first wiring pattern, (2) is the wiring board, (3
) is a through hole, (4) is a metal foil with an electrically insulating layer, (5
1 is a gold layer foil, (6) is a protective layer, (7) is a second wiring pattern, and (8) is a conductive material. Agent Patent Attorney Ishi 1) Choshichi

Claims (1)

[Claims] +11 Forming a first wiring pattern on the surface of the wiring board,
Next, the surface of the wiring board is heated to a temperature higher than the softening temperature of the resin, and the first wiring pattern is buried in the wiring board to smooth the surface of the wiring board, and then the surface of the wiring board is smoothed. Laminate the metal foils with the electrical insulating layer with the through-holes perforated so that the metal foils are on the front side, and align the holes with the wiring pattern position of 8S1. Then, a protective layer is applied in a pattern to cover the through-holes, a second wiring pattern is formed on the metal foil by etching, and after the protective layer is removed, a conductive material is filled into the through-holes to form a second wiring pattern. A method for manufacturing a multilayer printed wiring board, comprising electrically connecting a first wiring pattern and a second wiring pattern.