JPS58131798A - Multilayer 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 The present invention relates to a multilayer wiring board, and its objectives are to increase the density of wiring patterns, to simplify manufacturing processes, and to improve connections S between upper and lower wiring patterns (hereinafter referred to as interlayer connections). The purpose of this invention is to improve reliability, and it is intended to be particularly suitable for application to flexible multilayer wiring boards.

Conventional flexible multilayer wiring boards are shown, for example, in Figures 1 A to C (plan view) and Figures 2 A to C (sectional view).
Conductive foil (for example, steel 11'
)+2) and tat are pasted, and a through hole (4) is drilled at a position corresponding to the interlayer connection part. The upper and lower metal foils (2) and (3) are electrically connected by etching, and then both metal foils (2) and (3) are selectively etched into predetermined patterns to form wiring patterns (6) of IIIEI and $12.
) and (7). However, such a multilayer wiring board has the following drawbacks. First, through-hole plating is required, so the process becomes a badge-type process, making it impossible to make the manufacturing process continuous. If the diameter of the through hole (4) becomes small, the flow of the plating solution will be poor and a stable thickness cannot be obtained, so there is a limit to the through hole diameter (normally, the limit is 30 mm, 8 mm).

Since the metal plating t5J also adheres to the wiring pattern other than the through hole (4) portion, the flexibility of the multilayer wiring board is impaired. (approximately 1 to 2 hours to allow time for throughhole formation),
Moreover, since it passes through a hot water bath, it can be used as a flexible insulating base material [
In particular, only a limited number of moisture-resistant materials can be used.
Furthermore, when passing through acid, the acid is adsorbed into the insulating base material, which tends to cause remigration due to electrofusion after mounting. Furthermore, managing the plating solution is complicated, and since a large amount of wastewater is generated, a large-scale wastewater treatment facility is required, resulting in high costs.

The present invention provides a multilayer wiring board that has improved the above-mentioned drawbacks.

The following is a description of the multilayer wiring board according to the present invention using drawings. I!
Examples will be described in detail along with their manufacturing methods.

FIG. 3 shows an embodiment of the invention. However, this figure shows an interlayer connection part and is a perspective view with a part of it in cross section.

In the present invention, as shown in FIG. After forming the first wiring pattern u3 consisting of the following, for example, a circular shape is formed in the interlayer a portion (for example, circular shape) 13 of the first wiring pattern Q311 by punching or drilling as shown in FIG. 3B. Drill through hole I. At the time of forming the through hole I, it is also possible to simultaneously drill a lead insertion hole A for an electrical component in another hole (not shown).

Next, as shown in FIG. 3C, a through hole 1 is formed on the other surface of the substrate
A semi-hardened adhesive layer (for example, a conductive foil layer marked with 151, such as a steel foil layer tte) is laminated on the entire surface including 14 using a roll laminating device (for example, inserted through a pair of hot rolls heated to 1801Z'). This semi-hardened adhesive layer αS is not affected by the etching solution of the metal foil layer (for example, steel foil layer) that will be selectively etched later, but is dissolved in an organic solvent, and finally hardened by electron beam, heat, etc. It has properties such as three-dimensional hardening by applying energy and exhibiting cITIIi properties after hardening.

This adhesive layer α9 ultimately also serves as a support for the wiring pattern.

Next, as shown in the third diagram, the copper foil dovetails are selectively etched into a predetermined pattern using a photo-etching technique using electricity.
Form 2 wiring pattern 07).

At this time, the interlayer connection portion on the second wiring pattern yaD side is formed to be medium-thin, and is formed so as to fit just above the through hole Q4). In the selective etching of the steel foil layer 1e, the semi-hardened adhesive layer α9 remains without being etched.

Next, as shown in FIG. This solder resist layer (II has solvent resistance and serves as a mask member for selectively removing the adhesive layer α9 in the through hole (14) is formed by printing or the like. The connecting portions 0 and a. are formed so as to face the portions not covered by the layer Qs.

For a long time, as shown in Fig. 3F, an interlayer connection m5 (13 and
The adhesive layer (15) is selectively dissolved and removed using an organic solvent,
Open the through hole α (turn). At this time, Kf above the through hole α fathom,
The adhesive layer (15) on the back side of the connection part side of the long wiring II2 (turn aD) is also peeled off. Thereafter, the semi-hardened adhesive layer Q5 is hardened by electron beam, heat, etc.

Next, as shown in FIG.
7) High pressure cleaning of lI contact fd αυ (1 is Qi, <
Bend it into the through hole Q41' using the attached punch. Connection part us
It is preferable that the tip of the ill be protruded from the connection part α3 of the wiring pattern α of ill. In this case, as shown in Figure I114, the tip of connection 11 may be further bent to approach connection 1t (13) of turn a'JJ.

In addition, as shown in Figure 5, the thickness t of the insulating base material, the diameter of the through hole I, and the length of the connecting portion side are selected so as to satisfy 1) 1, ε≦L.

After that, as shown in Figure 3, open the through hole (141~).
[Conductive material gIjK] [Both connection parts 0 and the wire are electrically connected. At this time, as shown in the IF5 diagram, the electrical component r
It is also possible to insert a 2υ lead and then connect with conductive material ■. The conductive material 'PtCa is solder.

Pot paint, steel paint, carbon paint, calicum alloy (which initially forms a paste in the working equipment and then has the property of alloying and solidifying over time), etc. can be used. In this way, as shown in Figure II3 HK, the connection 5QII of one wiring pattern η is bent into the through hole I41, and the I
II Abe and the other connection (turn (I21 connection IB)
(13) are connected with a conductive material (to) to obtain the desired flexible multilayer wiring board Ω.

Such a multilayer wiring board (according to ZIK, one wiring pattern αη positive connection l5QII is bent into the through hole α4 in the interlayer connection part, and its tip is connected to the other wiring pattern Q3).
Connection 11 (close to 13, both connections Ikuo and αl)
The conductive material ■ is not attached to the other side only through the through hole α41, and therefore the multilayer layer is connected between the layers using the conventional plating method. The prettiness of the wiring board is superior to that of the wiring board. Also, since the relationship between the diameter L of the through hole α fathom, the length C of the m1llio pass, and the thickness t of the insulating base material is 1>tt≦L, the required diameter of the through hole Q41 is the thickness of the insulating base material. If the diameter is 1 or more, it will be difficult to use, and this makes it possible to make the through hole α fathom 11L sufficiently small, and it is possible to increase the density of the wiring pattern.

In addition, as shown in Figure 816, the lead of the electrical component G11l is inserted into the through hole a-fat in the interlayer connection part. Furthermore, interlayer connection KIIL? Since the solder flow can be used as is, interlayer connections can easily be made by soldering (in a few seconds) and LJ&, and in terms of manufacturing, since it does not have a metal fitting, continuity from side roll to roll is possible. This makes it possible to simplify manufacturing and reduce costs. Also, when connecting both connecting parts Q8 and 113 with molten solder dip, the through hole I
This becomes a hole for gas escape, which improves solder adhesion. In addition, since there is no intermediate process, the insulating base material can be freely selected, not only those with moisture resistance as in the past.
Moreover, no migration occurs.

Figure 7 shows another embodiment of the invention. In this example, a semi-cured adhesive layer is used as the insulating base material supporting the wiring pattern. First, as shown in Figure 7AK, a wiring pattern a made of a conductive foil layer, such as a steel foil layer, is formed on one main surface of the semi-cured adhesive layer a9. This can be obtained, for example, by butter-coating a steel foil layer with a semi-cured adhesive. In this case, the interlayer connection portion 0 of the first wiring pattern a3 is formed, for example, in a rectangular ring shape. Roll a conductive foil layer, for example, a steel foil layer ue, with a semi-hardened adhesive layer α9 on the other side of the adhesive 1 (15) having the wiring pattern a of this irises 1. Laminate and combine using a laminating device.

After a while, as shown in Figure 7eH, the steel foil layer 4 is selectively etched using a conventional photoetching technique to form the wiring pattern αη of the irises 2. At this time, the second wiring pattern αη
The medium-thin connecting portion of the wire corresponds to the position of the ring-shaped connection su3 of the coiled wiring pattern U3, and its outer dimension is equal to or smaller than the inner dimension of the connection 5 (131) Kl'C.

Next, as shown in Fig. 7 (1) K, connecting portions Q3 and u8 are formed on the surface of the screen on which the wiring patterns α2 and QD are formed, respectively.
A resist resist layer α is deposited by printing or the like so as to remove the remaining resist layer α. This crane f-resist layer Ql also serves as a mask member for selectively removing the adhesive layer α9, similar to the clay figure. After that, as shown in Figure 7, using the solder resist layer a and the steel foil connections (13 and d) as masks, apply the adhesive layer (19) surrounded by the annular connection αJ. is selectively dissolved and peeled off using an organic solvent to form a through hole a4.Thus, the wiring pattern α'r)ll of the rattan 2 is formed.
The connecting part - is located exactly above the through hole α. After selective etching of adhesive layer α9 is completed, adhesive layer a5
is cured to form an insulating support.

Next, as shown in FIG. II7F, a second wiring pattern aD is formed.
Bend the double connection part 0 seconds (the adhesive layer α9 on the back side has been peeled off) into the through hole α-1 using high-pressure cleaning or a punch with a taper, and make the wiring pattern of the irises 1 at the tip of the joint part Q.
3, as shown in FIG. 7Q, both connecting portions αJ and the solder are connected with a conductive material (2) such as solder to obtain the desired flexible multilayer wiring board.

This flexible multilayer wiring board (to) has the same effect as the case shown in FIG.
Manufacturing is easier, and since the through-holes are formed by chemical etching, the wiring pattern can be made finer. In addition, in the process of lE7#AB, the 8th #A
As shown in K, an insulating layer (up to) of arbitrary thickness can be inserted between the KM adhesive α by printing or the like.

The shape of the connection part α$ on the side of the iris 2 wiring pattern aη is 纂9a
In addition to the basic model in which a narrow connecting part α extending from one side is formed in the through hole α4 as shown in QA and BK, and this is bent into the through hole α, for example, in FIGS. 10 to 12. As shown in FIG.
5QI is formed, and the shape is bent into the through hole α as shown in Fig. 13 and connected with the conductive material (7), or connected on the through hole Q4 as shown in Fig. Various shapes are conceivable, such as a shape in which 11QI is divided into four parts and bent into each through hole Q4.

Figure 1115 shows still another embodiment of the present invention. This is a 4-layer arrangement, II pattern 61J, (b),
03 and the figure are laminated together via semi-cured adhesive αS, and the connecting portion of each pattern is <32 m.
), (33a), and (34m) can be bent into the through hole (141) and connected in common with its connection (31a).

Although the clay figure was applied to a flexible multilayer wiring board, it can also be applied to a multilayer wiring board using a hard substrate.

As mentioned above, according to the present invention, in the multilayer wiring board,
It is possible to improve the writing quality of the spread pattern 7, simplify the manufacturing process, and improve the reliability of the connection between one layer, and is particularly suitable for application to a flexible multilayer wiring board.

[Brief explanation of the drawing]

111111A-C is a plan view of a manufacturing process 1111 [showing an example of a conventional multilayer wiring board, and stripes A to C are respectively shown in FIG. 1A.
-CF)l -Ill is a cross-sectional view, Figure @3 is a partially cross-sectional perspective view showing an embodiment of the multilayer wiring board according to the present invention in the order of manufacturing steps, and Figures 114 to 6 are interlayer connections, respectively. FIG. 7 is a partially sectional perspective view showing another embodiment of the multilayer wiring board of the present invention in the order of manufacturing steps, and FIG. 8 is a partial cross-sectional view of the multilayer wiring board of the present invention. A cross-sectional view of an intermediate process showing another embodiment, Figures 121i and 121i are a plan view and a cross-sectional view after bending, respectively, showing the basic shape of the connection part applied to the present invention. A plan view showing a modified example of the shape of the connection part, Figure 13 is a sectional view after bending, and Figure 1
Figure 4 person and B are W! FIG. 15 is a plan view showing still another modification of the shape of the groove and a perspective view showing a bent state. FIG. 15 is a partially sectional perspective view showing still another embodiment of the multilayer wiring board of the present invention. αυ is an insulating substrate, α3Qη is a wiring pattern, α3Qs&
In the terminal connection part, α9 is a semi-cured adhesive layer, and ■ is a conductive material. 81st 1 Figure 12...l Ot: Figure 13 Figure 15 Continuation of page 1 Inventor Keiji Kurata Inside the Sony Corporation Haneda Factory, 5-21-15 Higashikojiya, Ota-ku, Tokyo

Claims (1)

[Claims] an insulating base material, a through hole provided at a predetermined position of the core insulating base material, a first conductive foil layer provided adjacent to the first ilK of the through hole of the insulating base material, and the insulating base material. First base material
a second conductive foil layer provided on the opposite side of the surface and having a bent portion in the through hole; and a multilayer wiring board made of a conductive material that connects the first and $112 conductive foil layers at the through hole. .