JPH0222893A - Manufacture of multilayered printed wiring board - Google Patents

Abstract

PURPOSE:To easily form a power supplying and grounding layer and, at the same time, to form no level difference in a conductive circuit so that a multilayered printed wiring board having no voids nor cracks can be formed by forming the layer from which a large current is supplied to components mounted on the circuit board by selectively performing copper plating to part of the board other than the part where through holes are formed so that the power supplying and grounding circuit can have no level deference with respect to its surrounding area. CONSTITUTION:A laminated plate 2 is coated with a photosensitive resist 3 and, after the resist 3 and a conductive layer 1 are successively removed from parts other than the parts 4 which are to be connected to through holes and a conductive circuit 6 is formed. Then the surface of the plate 2 is coated with a photosensitive plating resist 7 and the resist 7 is removed from parts other the parts 5 which are to be used for through holes. Then the plate 2 is dipped in a chemical copper plating solution and copper plating 8 is performed to the parts other than the parts 5 and a laminated body 10 is formed. Then, after such laminated bodies 10 are subjected to heating and pressure bonding with both-side printed wiring boards 11 provided with through holes and surface circuits with prepregs 12 in between, with a copper plate 13 being provided on the outside, through holes 14 are formed in the parts 5 which are to be used for through holes. Thereafter, a multilayered printed wiring board 20 having a smooth surface is obtained by forming through holes 16 and surface circuits 17.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a multilayer printed wiring board, and in particular, the present invention relates to a method for manufacturing a multilayer printed wiring board, in particular a multilayer printed wiring board having a thick conductor circuit in the power supply/ground layer for the purpose of supplying a large current to mounted components. The present invention relates to a method of manufacturing a power supply ground layer of a printed wiring board.

[Conventional technology]

Conventionally, a method for producing a multilayer printed wiring board involves etching away the portions of the conductive layer of an insulating plate having a conductive layer on the surface other than the portions where through holes are planned to be connected to the through holes to form conductive circuits, and・Double-sided printed wiring boards for ground circuits were created, and multiple double-sided printed wiring boards for power/ground circuits obtained in this way and multiple printed wiring boards with conductive circuits for signal circuits formed on both sides in advance. are placed on the outside with two insulating plates or two conductive plates having a conductive layer on one side, heated and pressed together via a plurality of prepregs to form a laminate, and a through hole is provided in the laminate, After through-hole plating, a surface circuit was formed by etching to obtain a multilayer printed wiring board.

[Problem to be solved by the invention]

However, the above-mentioned conventional method for manufacturing multilayer printed wiring boards,
In particular, in multilayer printed wiring boards that need to supply large currents to mounted components, it is necessary to form conductive circuits with thick conductors in the power supply and ground layers, which causes the following manufacturing problems. Was.

(1) When forming a conductive circuit in a power supply/ground layer, the conventional printing-etching method takes a long time to perform etching, and a uniform circuit shape cannot be obtained.

(2) In the through-hole forming process after forming the laminate, in the through-hole where the through-hole is connected to the power supply ground layer, for example, when drilling, the drill is used to cut a thick conductor part. There are significant bends and drill wear,
It is difficult to form through holes.

(3) Since the level difference in the conductive circuit of the power supply/ground layer becomes significantly large, the resin is not completely filled in when forming the laminate, resulting in voids, cracks, etc.

The purpose of the present invention is to eliminate the drawbacks of the conventional method, to easily and uniformly form a conductor circuit with a large conductor thickness in the formation of a power supply/ground layer, and to eliminate steps in the conductive circuit.

It is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board that is free from voids and cracks.

[Means to solve the problem]

The method for manufacturing a multilayer printed wiring board according to the first aspect of the present invention includes etching away portions of the conductive layer of an insulating plate having a conductive layer on the surface thereof, other than the portions to be connected to the through holes, to form a conductive circuit. forming a plating resist layer on the portion of the insulating plate where through-holes are to be formed, and applying copper plating to a portion of the conductive circuit other than the portion where through-holes are expected to be formed to partially increase the thickness of the conductive circuit; A step of creating a double-sided printed wiring board for ground circuits, and a step of combining the obtained double-sided printed wiring boards for power supply/ground circuits and a plurality of printed wiring boards with conductive circuits for signal circuits formed on both sides in advance on one side. Two insulating plates with conductive layers or two
A process of arranging two conductive plates on the outside and heat-pressing them through a plurality of prepregs to form an M carcass, and forming through holes in the laminated body, performing through-hole plating, and then forming a surface circuit by etching. It consists of a process.

Further, the method for manufacturing a multilayer printed wiring board according to the second aspect of the present invention includes etching and removing a portion of the conductive layer of an insulating plate having a conductive layer on the surface thereof, other than the portion where the through hole is to be formed, other than the portion where the through hole is to be connected. a step of forming a conductive circuit, forming a plating resist layer on the portion of the insulating plate where through holes are to be formed, and applying copper plating to a portion of the conductive circuit other than the portion where through holes are to be formed to partially increase the thickness of the conductive circuit; a step of removing the plating resist layer and providing an insulating layer on the surface of the insulating plate to create a double-sided printed wiring board for power supply/ground circuits; and a step of creating a double-sided printed wiring board for power supply/ground circuits obtained above. A board and a plurality of printed wiring boards on which conductive circuits for signal circuits have been formed on both sides in advance, and two insulating plates or two conductive plates having a conductive layer on one side are placed on the outside (U), and a plurality of prepregs are placed on the outside. The method is characterized by comprising the steps of: forming a laminate by heat-pressing the laminate; and forming through-holes in the laminate, performing through-hole plating, and then forming a surface circuit by etching.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIGS. 1(a) to 1(h) are cross-sectional views of a multilayer printed wiring board shown in the order of steps to explain an embodiment of the present invention.

First, as shown in FIG. 1(a), an M-layer plate 2 made of glass fiber-containing polyimide resin and having a conductive layer 1 of 18 μm thick on both sides is prepared.

Next, as shown in FIG. 1(b), a photosensitive etching resist 3 is laminated on the entire surface, and through-hole planned areas 5 are
After exposure, the etching resist 3 in the area other than the planned through-hole connection area 4 is developed and removed. Next, Figure 1(c)
As shown in FIG.
), the etching resist 3 is removed and a conductive circuit 6 is formed.

Next, as shown in FIG. 1(e), a photosensitive plating resist 7 with a thickness of 200 μm is laminated on the surface of the laminate 2, and then exposed and developed to remove areas other than the areas 5 where through holes are to be formed. Partial plating resist 7 is removed. Next, as shown in FIG. 1(f), the laminate 2 is immersed in an electroless copper plating solution, and 180 μm of copper plating 8 is applied to the portions other than the portions 5 where through holes are to be formed. form 10. Next, as shown in FIG. 1(g), the double-sided printed wiring board 11 on which through-holes and surface circuits have been formed in advance and the power supply/ground circuit laminate 10 are placed with a prepreg 12 in between, and a copper plate 13 is placed on the outside. After heat-pressing, a through-hole 14 is formed in the through-hole formation area 5 using a drill.Next, as shown in FIG. Forming the through-holes 16 and surface circuits 17 using a print-etching method results in a multilayer printed wiring 20 formed according to an embodiment of the present invention.

The multilayer printed wiring board thus obtained has a thick power supply/ground circuit with a uniform shape within the multilayer printed wiring board,
Moreover, it is easy to form through holes during the manufacturing process, and since the thick power supply ground circuit formation and plating resist are left intact, the surface is smooth and free of voids and cracks. .

In the above embodiment, the laminate 2 was copper plated using electroless copper plating in order to increase the thickness of the conductive circuit, but the same effect can be obtained by using electrolytic copper plating.

FIGS. 2(a) to 2(j) are cross-sectional views of a multilayer printed wiring board shown in the order of steps for explaining another embodiment of the present invention.

As is clear from FIGS. 2(a) to 2(j), the process from FIG. 2(a) to FIG. 2(f) is similar to that shown in FIG. 1(a).
), the process is the same as that shown in FIG. 1(f), so the explanation will be omitted.

Next, as shown in FIG. 1(g), the plating resist 7 is removed. Next, as shown in FIG. 2(h), an insulating layer N9 mainly composed of polyimide resin is formed on the surface by screen printing, and the surface is covered with an insulating layer and flattened to form a power/ground circuit laminate 10. get.

Next, a multilayer printed wiring board according to the second invention of the present invention is obtained by going through the steps shown in FIG. 2(i) and FIG. Detailed explanations will be omitted since they are only different.

Note that, similar to the first invention, the copper plating may be performed by electrolytic copper plating instead of electroless copper plating.

According to this embodiment, compared to the first embodiment, the plating resist of the power/ground circuit laminate is removed and an insulating layer mainly composed of polyimide resin is formed, resulting in a more flat surface and improved reliability. An excellent multilayer printed wiring board can be obtained.

〔Effect of the invention〕

As explained above, the present invention particularly relates to the formation of a power supply/ground layer of a multilayer printed wiring board that supplies a large current to mounted components by selectively applying copper plating to areas other than through holes, and of forming a power supply/ground circuit. By filling in the steps, it is possible to easily manufacture a multilayer printed wiring board without voids or cracks.

Multilayer printed wiring board.

[Brief explanation of the drawing]

FIGS. 1(a) to (h) are cross-sectional views of a multilayer printed wiring board shown in the order of steps for explaining one embodiment of the present invention, and FIG.
a) to (j) are cross-sectional views of a multilayer printed wiring board shown in the order of steps to explain other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Conductive layer, 2... Box layer board (insulating board), 3...
Etching resist, 4...Through hole connection planned area,
5... Through hole planned portion, 6... Conductive circuit, 7...
- Plating resist, 8... Copper plating, 10... Laminate for power supply/ground circuit (double-sided printed wiring board for power/ground circuit), 11... Double-sided printed wiring board, 12... Prepreg, 13 ...Copper plate, 14...Through hole, 15.
...Copper plating, 16...Through hole, 17...Surface circuit, 20...Kayabou

Claims (2)

[Claims] (1) A step of forming a conductive circuit by etching away a portion of the conductive layer of an insulating plate having a conductive layer on its surface, other than a portion to be connected to the through hole, and a portion of the insulating plate where the through hole is to be formed. A plating resist layer is formed on the conductive circuit, and copper plating is applied to the portions of the conductive circuit other than the portions where through holes are planned to be formed to partially increase the thickness of the conductive circuit.
A process of creating double-sided printed wiring boards for ground circuits, and a process of forming a plurality of double-sided printed wiring boards for power ground circuits obtained above and a plurality of printed wiring boards on which conductive circuits for signal circuits have been formed on both sides in advance to conductive circuits on one side. A process of arranging two insulating plates or two conductive plates having layers on the outside and heat-pressing them through a plurality of prepregs to form a laminate, and forming a through hole in the laminate and performing through-hole plating. 1. A method for producing a multilayer printed wiring board, comprising the step of forming a surface circuit by etching after the step of forming a surface circuit. (2) forming a conductive circuit by etching away a portion of the conductive layer of the insulating plate having a conductive layer on its surface, other than the portion to be connected to the through hole; and a step of forming a conductive circuit in the through hole planned portion of the insulating plate a step of forming a plating resist layer on the surface of the insulating plate, and applying copper plating to a portion of the conductive circuit other than the portion where through holes are to be formed to partially increase the thickness of the conductive circuit; A step of providing an insulating layer and creating a double-sided printed wiring board for power supply/ground circuits, and a plurality of double-sided printed wiring boards for power supply/ground circuits obtained above and a plurality of double-sided printed wiring boards for signal circuits on both sides of which are formed in advance. A process of forming a laminate by placing two insulating plates having a conductive layer on one side or two conductive plates on the outside of the printed wiring board and bonding them under heat through a plurality of prepregs, and forming a laminate through the laminate. 1. A method for producing a multilayer printed wiring board, comprising the steps of forming holes, performing through-hole plating, and then forming a surface circuit by etching.