JPS6041290A - Method of producing multilayer wiring 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 The present invention relates to a method for manufacturing a multilayer wiring board that can be obtained at high quality and at low cost.

As a conventional multilayer wiring board, for example, as shown in FIGS. 1A and 1B, a first wiring pattern (2) of copper foil is formed on a thick insulating board (1) of paper phenol or paper epoxy. A so-called hard wiring board (3), a resin film (4) made of polyimide, polyester, etc., and a second layer made of copper foil.
A so-called flexible wiring board (6) formed by completely forming the wiring pattern (5) is laminated and combined with an adhesive insulating layer (for example, epoxy type) (by force), and the upper and lower wiring R is formed by a conductive material (8). A multilayer wiring board (9) in which turns (5) and (2) are connected is known. 0Q is an electrical component mounted on this board (9), and α force is solder.

By the way, in the multilayer wiring board (9) having such a configuration,
Distance (step) between upper and lower wiring patterns (2) and (5)
is large, both patterns (2
) and (5) are unreliable, and there are no electrical components.
At the connection part (b) of I, it is impossible to directly solder both patterns (2) and (5) at the same time with solder α when mounting the component, and the flexible wiring board (6
), it is difficult to drill microholes with a diameter of 1 mm or less far apart, making it difficult to obtain high-quality products or high-density circuits. Also, during manufacturing, as shown in FIG. 2, the arrangement of the upper layer tM, /f turns (5
) is formed by selective etching, the lower layer wiring pattern (2) facing inside the through hole 0 is attacked by the etching solution (
(symbol a→illustration), it was necessary to fill the inside of the through hole α→ in advance, which made manufacturing complicated.

In view of the above-mentioned points, the present invention provides a method for manufacturing a multilayer wiring board that can be obtained at high quality and at low cost, and also enables high-density circuit formation.

In the present invention, a first wiring (turn) is formed on an insulating support, and an insulating resin layer is formed on the insulating support on which the first wiring/mother turn is formed, except for the upper and lower connection parts. form and heat roll through the adhesive layer on this insulating resin layer,
Conductor foils are laminated by heat pressing, etc., and the conductor foil is etched to form nine turns (second wiring), and then the adhesive layer at the upper and lower connection parts is removed, and the first and second wirings are formed. A high-quality, low-cost multilayer wiring board is manufactured by connecting the upper and lower connecting portions of a wiring pattern with a conductive material.

Embodiments of the method for manufacturing a multilayer wiring board according to the present invention will be described in detail below with reference to the drawings.

Figures 3 and 4 are examples of the present invention manufactured by roll lamination. In the present invention, as shown in FIG. 4A, an insulating substrate (thickness 1
．． 6■~0.8m+) @]) 15μ~35 on the - side
A so-called hard wiring board is prepared by preparing a copper-clad laminated board covered with μ-thick copper foil (Q) and selectively etching the copper foil () to form a first wiring pattern (E). (c) shall be provided.

As shown in FIG. 4B, 10 to 1
An insulating resin layer having a thickness of 20 to 70 μm, preferably 0.0 μm, preferably 4 μm. xyacrylate type, spiroacetal type,
An ultraviolet curable P green resin layer C9 made of urethane acrylate or the like is formed by printing except for the connecting portion (23a) of the first wiring pattern (c). Since this ultraviolet curable insulating resin layer (c) contains a solvent, it has no pin poles and can be formed into a single layer.

Incidentally, when an epoxy acrylate resin is used as the insulating resin layer (c), it is preferable to treat the surface of the resin layer in order to improve the adhesion to the copper foil to be bonded later. This surface treatment method includes a sandblasting method in which 325-mesh iron powder is sprayed on the entire surface, a brushing method in which the entire surface is brushed with 180-grit No. 11, surface roughening by corona discharge or plasma, and methylene chloride,
There are solvent etching methods such as trichlene and cellosolve. As the insulating resin layer (c), in addition to the above-mentioned ultraviolet curing type, paints such as polybutadiene, epoxy, and epoxy-melamine can also be used.

Next, as shown in Figure 4 C and D, a copper foil with an adhesive (c) on the back side with a thickness of about 15 μm to 35 μm is glued onto the substrate (c) on which the insulating resin layer (c) is printed. Laminated and combined.

As the adhesive (c), thermosetting resins such as epoxy acrylic or epoxy nitrile, thermosetting resins such as polyamide or ethylene-vinyl acetate (melting point 80°C to 2
00° C.) or electron beam curing type epoxy acrylate. In order to improve productivity, a roll laminating device (c) shown in FIG. 3 is used to laminate such copper foils (goods). This device (c) consists of a plurality of rolls along the transport direction of a conveying belt for sequentially transporting the material of the multilayer wiring board, namely a pair of silicone rubber rolls (7) heated to 165° C. and a similar 165° C.
It consists of a metal opening (5) made of stainless steel or chrome plated heated to ℃. According to this device (c),
The force of the printed board with the insulating resin layer (c) is transferred to the feeding belt (
When it is sent to position The copper foil is laminated and integrated on the substrate (c) after passing through a period of 0η. The board (C) at position X2 in Figure 3 is located at C in Figure 4.
, and the substrate C1 at position X3 corresponds to the fourth diagram. That is, the copper foil (b) is bonded by multiple presses so that the curved surface thereof becomes flat.

Next, as shown in Figure 4E, selective etching is applied to the copper foil (), the portion corresponding to the connection part (23a) of the 9th turn (A) of the underlying wiring is removed, and the adhesive is removed. is removed to form zero openings leading to the connection portion (23a). Next, as shown in FIG. 4F, the copper foil (C) is selectively etched to form a second wiring pattern 01. During this turning, as shown in Fig. 5, the first wiring pattern) and the copper foil (a), that is, the second wiring/mother turn 0'3
Since the distance (step) between the resist ink and the
In the first printing, the resist in (6) 03 is simultaneously printed inside the opening 02, so that the first wiring/mother turn (c) is not eroded by the etching solution.

After that, the resist ink (13) is removed, and the opening 0 is filled with a conductive material 0, and the upper and lower wiring patterns (c) and 01 are connected to form the desired multilayer wiring as shown in Fig. 4G. Obtain substrate 0→.

As the conductive material 00, conductive materials such as gallium alloy, solder dip, silver paste), metal spraying (plasma spraying, arc spraying) with low melting point metals such as Cu + Zn I Sn, and conductive materials such as solder coater leveler treatment are used. obtain.

In particular, in the case of gallium alloys, gallium Ga is in a liquid state at room temperature below 30°C, a metal that is eutectic with this gallium, and a metal powder (single metal powder or alloy powder) that can be alloyed with gallium and raise its melting point. It consists of a mixture of This gallium alloy conductive material has the property of initially forming a paste-like form at the working temperature, and then alloying and solidifying over time. Metals that are eutectic with gallium include indium In, tin n, zinc Zn, and bismuth B.
One or a combination of two or more of the following metals, preferably indium In, tin Sn, etc., may be used. Examples of metal powders that can be alloyed with gallium include nickel (Ni, Conol 9) C
o, single metals such as gold (Au), copper (Cu), or alloys thereof such as N1-Cu alloy, co-metal alloys such as Co-Sn alloy, copper alloys such as Cu-Sn alloy (Cu 40 weight coefficient or more) , Cu-Zn alloy (Cu 6
0 weight coefficient or more), Cu-Be alloy (Cu 98 weight coefficient or more), etc. may be used. This metal powder is desirably one that does not form an oxide film, and is particularly suitable for Sn+Z in the above-mentioned copper alloy.
n, Bs+, etc. are preferable in order to prevent oxidation of Cu. The particle size of these metal powders is 0.5μ to 500μ
The range is preferably 1.0μ to 100μ. When this gallium alloy is used, the problem of silver migration that occurs with silver paint is avoided, and the conductivity is equivalent to that of Cu plating, making it possible to form high-quality and higher-density circuits.

There are two ways to manufacture the multilayer wiring board using the roll lamination method on the upper side. One is to form an opening for connection in the copper foil (b) in advance, and the other is as shown in Figure 4. In this method, a copper foil (A) is laminated on a substrate (C) in the same manner as in the above, and a rear opening 0→ is provided. FIG. 6 shows the former case, and FIG. 7 shows the latter case.

That is, in FIGS. 6A to 6E, the first wiring i4-turn block is formed, and the entire surface except for the connection part (23a)' is covered with insulating resin N.
After printing (c), copper foil with openings formed in advance @
The layers are combined using a roll press, and then the copper foil (A) is applied.
A conductive material such as gallium alloy 04 is formed in the opening 0 by patterning to form a second wiring/mother turn 03.
f: Fill and connect both patterns (c) and 03.

Further, a lead insertion hole (to) is provided, and the lead of the electrical component α1 is joined here.

In Figures 7 A to E, after forming the first wiring hole and turn (E) and printing an insulating resin layer (C) on the entire surface except for the connection part (23a), the copper foil @ is overlaid. The layers are laminated and combined using a roll press, and then an opening 0 and a second wiring turn 0'3 are formed by chemical etching. Note that the opening Oat is first drilled, and then the second hole is drilled as in the method shown in Figure 6.
Wiring AI turn (31 A? Turning may be performed. After that, if there is an adhesive layer in the opening (9), remove it with an organic solvent, and then open the opening C3.
For example, fill → with gallium alloy (→, and electrical parts 0O
Form the lead insertion hole ((Q).Here, as shown in Figure 8, at the lead connection part 0 to 0 of the electrical component On, simultaneously solder the lead and connect between both the upper and lower patterns (C) and 01. It can be done.Also, electrical parts can be
Even when there is no mount, if a through hole 0→ which penetrates the substrate (C) is provided at the connection portion as shown in FIG. 9B, the bonding performance by the conductive material 04 will be further improved. Therefore, the form of the upper and lower patterns (c) and the joint portion of 01 can be configured as shown in FIG. 9A or FIG. 9B.

FIG. 10 shows another embodiment of the invention suitable for high frequency applications. This is done by forming a metal layer (shield layer) (+n) made of, for example, metal spraying, silver paste, copper paste, At, Nl, Cu, or other vapor deposited layer on the insulating resin layer (c), and then This is made by printing an insulating resin layer (c) to form a second wiring pattern (a) made of copper foil, and this metal layer θO allows both patterns (a) and 03
The space between the two is shielded, making it suitable as a high frequency substrate (10).

Further, the present invention, for example, as shown in FIG. 11, for a so-called first wiring board 0η having a wiring pattern formed on both sides thereof, insulating resin layers (c) are printed in the same way on both sides,
Glue the copper foil and connect the second wiring. A multilayer wiring structure in which turns are formed can also be used.

Furthermore, the present invention can also be made into a multilayer wiring structure laminated on a through-hole substrate as shown in FIG. That is, as shown in the figure, an insulating substrate (thickness 1.6 tm ~
4 turns (23A) and (23B) of the first wiring using copper foil with a thickness of 15μ to 35μ on both sides of the QT).
and both required wiring patterns (23A) and (23B) are formed through the conductive plating layer Φυ in the through hole.
A double-sided board consisting of a double-sided board is provided, and on top of this, an insulating resin layer (made of paint such as butadiene, epoxy, epoxy-melamine, etc.) is printed except for the connection parts, and then glued on the back side. The copper foil coated with the agent (G) is adhered and patterned to form the second wiring turn 01, and the opening is filled with a conductive material (B) to form the upper and lower wiring patterns (
Connect 23A) and 03. Repeat this further for the third step. Fourth wiring patterns M and fi41 are formed to form a multilayer structure. A multilayer wiring board with such a structure is a multilayer board with thin layers, so there is no complexity in the lamination process, and a reliable, high-density, low-cost multilayer board that does not cause phenomena such as smearing is produced. can get. Furthermore, when a gallium alloy is used as the conductive material, the disadvantages of the silver electromigration phenomenon, poor high frequency characteristics, and excessively large electrical resistance in the silver-based method are eliminated. In this configuration, the double-sided substrate 62 side of the through-hole plate made of the insulating substrate of the rigid lift can be used as a high frequency circuit, and the laminated circuit sandwiching the thin film insulating layer (c) can be used as a signal line. Note that the risot circuit is not limited to a double-sided board with through-hole plating, and through-hole techniques such as eyelets, bottle stands, silver through-hole boards, and gallium alloys may be used.

Incidentally, if the insulating resin layer (c) is made of a material having an adhesive property of 1 kW, the adhesive (c) on the back surface of the copper foil (c) can be omitted.

According to the present invention described above, the copper foil is bonded onto the first wiring board (c) on which the first wiring pattern (a) is formed via the insulating resin layer (c) formed by printing, and the no. 9 to form a second wiring pattern 03, and conductive material 0 filled in the opening 0 of the second wiring pattern (c).
By configuring the upper and lower patterns (E) and (To) to be connected by 4, the distance (step) between both patterns (C) and 01 at the connection part is extremely small (about 5 μ to 20 μ), However, at the opening 0→, the edge of the second wiring pattern 01 sag inward as shown in FIG. This allows for highly reliable through-hole connections.

Also, since the distance between the upper and lower pattern lines and (to) is small,
As explained in FIG. 5, the resist ink .alpha.J can be printed even within the opening 0 during the R turning of the copper foil (a), facilitating the selective etching process. Furthermore, when mounting the electrical component 01 with a solder dip, (13) the solder dip simultaneously enables connection between both patterns (c) and 03 at the lead connection portion.

In addition, since the opening (b) of the second wiring pattern 03 can be made by chemical etching, it is possible to form the opening 04 with a minute diameter (approximately 0.4 mm diameter), and it is also possible to form fine circuits and mother turns. It becomes possible. In addition, when using a gallium alloy as the conductive material 64, it is suitable for high-density circuits without causing electromigration like silver paint, short-circuiting of adjacent circuits, has good conductivity and high frequency characteristics, and is suitable for filling paste. There are advantages such as no volumetric shrinkage and improved connection reliability. Further, the insulation between the first circuit and the second circuit can be set to a sufficient thickness using an insulating resin and an adhesive, and the electrical insulation properties are also excellent.

As described above, the present invention can provide a multilayer wiring board with high quality and high density circuits at low cost.

[Brief explanation of drawings]

Figures 1A and B are cross-sectional views showing the process order of an example of a conventional multilayer wiring board, Figure 2 is a cross-sectional view for explaining the conventional method (14), and Figure 3 is a case in which the multilayer wiring board of the present invention is obtained. No 0
-# A perspective view showing an example of a laminating device, FIGS. 4A and 4G are cross-sectional views showing an example of the present invention in the order of manufacturing steps, FIG. 5 is a cross-sectional view for explaining the present invention, and FIGS. 6-E 7 is a perspective view of the process order showing an example of the manufacturing method of the present invention, FIGS. 7A to 7E are perspective views of the process order of another manufacturing method example of the present invention, and FIG. FIGS. 9A and 9B are perspective views showing an example of the connecting portion of the present invention, FIGS. 10 and 11 are sectional views showing still other examples of the present invention, and FIG. 12 is a perspective view showing an example of the connecting portion of the present invention. FIG. 13 is a cross-sectional view showing still another example of the present invention. (Foundation) is an insulating substrate, board is the first wiring pattern, □□□ is an insulating resin layer, (c) is an adhesive, ni) is a copper foil, (3■ is an opening, G3 is a second wiring pattern, ( b) is a conductive substance. (15)

Claims (1)

[Claims] A step of forming a first wiring f-turn on the insulating support, and a step of forming an insulating resin layer on the insulating support on which the first four turns of the wiring are formed, excluding the upper and lower connection portions. ,
a step of laminating a conductor foil on the insulating resin layer via an adhesive layer, a step of etching the conductor foil to form a second wiring pattern, a step of removing the adhesive layer at the upper and lower connection parts, Method O for manufacturing a multilayer wiring board comprising the step of connecting the upper and lower connection parts of the first and second wiring patterns with a conductive substance