JPH06101627B2 - Multilayer printed wiring board and manufacturing method thereof - Google Patents

Description

The present invention relates to a multilayer printed wiring board and a method for manufacturing the same,
In particular, the present invention relates to a multilayer printed wiring board having surface mounting pads for mounting surface mounting components and a method for manufacturing the same.

[Conventional technology]

Conventionally, the surface of a printed wiring board for mounting surface mounting components is provided with a surface mounting pad with a flat surface structure, and the electrical connection between the surface mounting component terminals and the surface mounting pad of the printed wiring board is The mechanical joining was performed via cream solder or the like.

The method of manufacturing a printed wiring board having such surface mounting pads is no different from the method of manufacturing a normal printed wiring board.

That is, in the case of a multilayer printed wiring board, a printed wiring board having conductive circuits formed on one side or both sides is heated and pressure-bonded through a plurality of prepregs to form a laminated body, and after a through hole is provided, panel plating is performed on the entire surface. Are formed to form through holes, and then a surface mounting pad is formed simultaneously with a surface circuit by a printing-etching method.

[Problems to be Solved by the Invention]

Since the surface mounting pad of the conventional printed wiring board described above has a flat surface, compared to the method of soldering after inserting the component lead into the usual through hole, the surface mounting pad for surface mounting of the terminal of the surface mounting component and the printed wiring board is used. There is a drawback in that the mechanical strength of the solder connection portion with the pad is not sufficient.

An object of the present invention is to provide a multilayer printed wiring board having high mechanical strength at a solder connection portion between a surface mount component terminal and a surface mounting pad of the printed wiring board and having high reliability, and a manufacturing method thereof.

[Means for Solving the Problems]

The multilayer printed wiring board of the present invention has a surface-mounting pad, has a cylindrical shape, and the size of the outer circumference of the cylindrical shape is smaller than the outer circumference of the surface-mounting pad, and The surface mounting is a recess that is larger than the outer circumference, is copper-plated over the entire surface including the bottom surface and side surfaces, and is integrated with the upper surface of a via hole that is previously provided as a buried through hole to connect to the internal circuit. Is formed in the center of the surface of the pad.

The method for manufacturing a multilayer printed wiring board according to the present invention is a method in which a through hole is provided in a copper-clad laminated board on both sides, copper is plated on the entire surface including the inner wall of the through hole to form a through hole, and only one surface is printed-etching method. A step of manufacturing a double-sided printed wiring board by forming a conductive circuit, and a prepreg together with a double-sided printed wiring board for a power ground in which a conductive circuit is formed in advance with the surface of the double-sided printed wiring board on which the conductive circuit is formed as an inner side. A step of heating and crimping to form a laminated body to form a laminate, and a method of polishing and removing the resin of the prepreg that has overflowed from the through hole to the surface during heating and crimping, and further applying the resin to O ₂ -CF ₄ plasma, And the resin filled in the through hole by etching using any one of alkaline permanganate, chromic acid-sulfuric acid and agricultural sulfuric acid. A step of removing a predetermined depth from the surface to form a groove, and forming a through hole in the laminated body, performing copper plating on the entire surface including the through hole and the groove, and then performing a printing-etching method for a surface mounting pad , A step of forming a multi-layer printed board including surface circuits and through holes.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical cross-sectional view of a main part of a multilayer printed wiring board and surface mounting components for explaining the structure of the first embodiment of the present invention.

In the first embodiment, as shown in FIG. 1, the multilayer printed wiring board 22 has a surface mounting pad 18 having a recess 16 and a surface circuit 1.
7, the internal circuit 19, the power supply / ground layer 20, the through hole 15, and the insulator 21, and the position and shape of the recess 16 of the surface mounting pad 18 is such that the component terminal 31 of the surface mounting component 30 is inserted. ing.

2 (a) and 2 (b) are a plan view and a longitudinal sectional view for explaining the structure of the surface mounting pad of the first embodiment of the present invention.

As shown in FIGS. 2A and 2B, the surface mounting pad
18 and the recess 16 are circular, and a copper plating layer 14 is provided on the bottom surface and side surfaces of the recess 16 and on the upper surface of the surface mounting pad, and these are composed of the copper foil 1 and the copper plating layer 4. It is formed on the via hole 23.

FIGS. 3 (a) to 3 (i) are longitudinal cross-sectional views of a main part showing the order of steps for explaining the manufacturing method according to the first embodiment of the present invention.

In the manufacturing method of the first embodiment, first, a 0.1 mm thick laminated plate 2 having 18 μm copper foils 1 on both sides is prepared.

Next, as shown in FIG. 3 (b), a glass fiber reinforced epoxy base material is used as the laminate 2, and a portion for connecting through-holes of front and back circuits of the laminate 2 and a portion for forming the surface mounting pad 18 are formed. A through hole 3 is formed by using a drill.

Next, as shown in FIG. 3 (c), ordinary catalyst activation-electroless copper plating is applied to the entire surface of the laminated plate 2 including the wall surface of the through hole 3, and then electrolytic copper plating is applied to 20 μm to form copper. Plating layer 4
To form.

Next, as shown in FIG. 3 (d), normal printing-on one surface of the laminated board 2 on the side to be the internal circuit of the multilayer printed wiring board-
The conductive circuit 6 is formed by the etching method to obtain the double-sided printed wiring board 7.

Next, as shown in FIG. 3 (e), two double-sided printed wiring boards 7 thus obtained and a copper foil-clad laminated board are prepared by printing and etching in advance. The power supply / ground double-sided printed wiring board 9 was heated and pressure-bonded through the prepreg 8 to obtain a laminate 10. On this occasion,
A glass fiber reinforced semi-cured epoxy resin was used as the prepreg 8. During heating and pressure bonding, the epoxy resin of the prepreg 8 flows into the inside of the through hole 5 of the double-sided printed wiring board 7 arranged outside and is filled.

Next, as shown in FIG. 3 (f), after the epoxy resin that has overflowed to the outside and adhered thinly to the surface of the laminated body 10 is polished and removed by buffing to smooth the surface of the laminated body 10,
The laminate 10 was treated with O ₂ and CF ₄ mixed gas plasma for 3 hours by a plasma etching apparatus to remove the surface of the resin portion 11 by about 50 μm by etching to form the groove 12.

Next, as shown in FIG. 3 (g), through holes 13 are formed in the laminated body 10.
To provide.

Next, as shown in FIG. 3 (h), the wall surface of the through hole 13 and the groove
A general catalyst activation-electroless copper plating is applied to the entire surface of the laminate 10 including the bottom surface of 12 and then electrolytic copper plating is applied to a thickness of 3 μm to form a copper plating layer 14. At this time, the recess 16 was formed in the planned surface mounting pad.

Next, as shown in FIG. 3 (i), the surface of the laminate 10 is copper-etched by a normal printing-etching method to form the surface mounting pads 18, the through holes 15 and the surface circuits 17, and the internal circuit 19 is formed. Thus, a multilayer printed wiring board 22 including the power / ground layer 20 was obtained.

As the second embodiment, the structure of the surface mounting pad is the same as that of the first embodiment shown in FIG. 3 (e), and the resin portion 11 of the laminate 10 of the manufacturing method is subjected to an alkaline etching process. A multilayer printed wiring board having a surface-mounting pad 18 was prepared in exactly the same manner as in the first embodiment except that the groove 12 of about 50 μm was formed by immersing in a potassium manganate aqueous solution for 1.5 hours.

〔The invention's effect〕

The multilayer printed wiring boards having the surface-mounting pads obtained in the first and second embodiments are both well soldered when the component terminals of the surface-mounting components and the surface-mounting pads are soldered. Has a mechanical strength, and has an effect that a highly reliable solder connection can be obtained.

[Brief description of drawings]

FIG. 1 is a longitudinal cross-sectional view of a main part of a multilayer printed wiring board and surface mounting components for explaining the structure of the first embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are the first embodiment of the present invention. FIG. 3A is a plan view and a vertical sectional view for explaining the structure of the surface mounting pad of the first embodiment, and FIGS. 3A to 3I are for explaining the manufacturing method of the first embodiment of the present invention. It is a longitudinal cross-sectional view of a main part shown in the order of steps. 1 ... Copper foil, 2 ... Laminated plate, 3 ... Through hole, 4 ... Copper plating layer, 5 ... Through hole, 6 ... Conductive circuit, 7 ... Double-sided printed wiring board, 8 ... Prepreg, 9 ...... Power supply / ground double-sided printed wiring board, 10 …… Laminate, 11 …… Resin part, 12 …… Groove, 13 …… Through hole, 14 …… Copper plating layer, 15
…… Through hole, 16 …… Concave, 17 …… Surface circuit, 18 ……
Surface mounting pad, 19 ... Internal circuit, 20 ... Power / ground layer, 21 ... Insulator, 22 ... Multilayer printed wiring board, 23
…… Beer hole, 30 …… Surface mount component, 31 …… Component terminal.

Claims (2)

[Claims] 1. A surface-mounting pad, wherein the shape is cylindrical, and the size of the outer circumference of the cylindrical shape is smaller than the outer circumference of the surface-mounting pad and larger than the outer circumference of the terminal of the surface-mounting component. , The entire surface including the bottom surface and the side surface is plated with copper, and a recess having a structure integrally formed on the upper surface of a via hole provided as a buried through hole to be connected to an internal circuit in advance is provided on the surface of the surface mounting pad. A multilayer printed wiring board characterized by being formed in the center. 2. A through hole is provided in a copper-clad laminated plate on both sides,
After forming a through hole by copper plating on the entire surface including the inner wall of the through hole, a step of producing a conductive circuit by a printing-etching method on only one surface to produce a double-sided printed wiring board, and the conductive circuit of the double-sided printed wiring board A process of heating and pressure bonding through a prepreg to form a laminated body with a double-sided printed wiring board for power ground on which a conductive circuit is formed in advance with the formed surface as an inner side, and the through hole at the time of heating and pressure bonding. The resin of the prepreg overflowing to the surface is removed by polishing, and the resin is further treated with O ₂ —CF ₄ plasma, and alkaline permanganate, chromic acid-sulfuric acid,
A step of forming a groove by removing from the surface a predetermined depth of the resin that has been etched and filled in the through hole using one of the methods of using agricultural sulfuric acid; and providing a through hole in the laminate. A step of forming a multilayer printed board including a surface mounting pad, a surface circuit and a through hole by a printing-etching method after copper plating is applied to the entire surface including the through hole and the groove. Wiring board manufacturing method.