JPH1177190A - Press forming die having protrusion for pressing die and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a forming die to press-form a protruded/bent part to a lead on a circuit board by providing a protrusion for pressing the die formed with plating growth on the surface of a base made of a metal plating layer. SOLUTION: A press forming die 1 formes a sheet like base 2 in a metal plating layer 3 and has many protrusions 4 for pressing the die which are protruded from one side surface of the plating layer 3. The protrusions 4 are formed with a part of the plating layer 3. Accordingly, the plating layer 3 and the protrusions 4 are formed with a same metal (a suitable one is nickel plating, etc.). By this plating method, the protrusions 4 are precisely and easily formed. By using this press forming die 1, a protruded/bent part for connection between the layers of a circuit board is formed in high precision to execute highly reliable connection between the layers. Further, even in the case that a lead forming a circuit is fine at a narrow pitch, the protruded/bent part is easily formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press forming die used for press forming a bent portion as an interlayer connecting means on a lead on a printed circuit board, and a method of manufacturing the press forming die.

[0002]

2. Description of the Related Art In recent years, the high performance and high performance of electronic equipment have been remarkable, and with this, the pitch of leads on a circuit board has become narrower and finer, and the cost has been required to be reduced at the same time. It has become.

As a circuit board, a rigid multilayer circuit board, a flexible multilayer circuit board, or a rigid flexible multilayer circuit board which is a composite of these boards has been used in many cases. Such a multilayer circuit board has an interlayer connection, that is, a circuit. Leads forming a multilayer circuit on a substrate must be electrically connected at a number of places, and an interlayer connection method through through holes is generally employed.

In the interlayer connection method using the through holes, as shown in FIG. 1A, a double-sided copper-clad laminate in which copper foils 1 and 2 are bonded to both sides of an insulating sheet 3 is formed, and leads of the double-sided copper-clad laminate are formed. After drilling a corresponding portion with a drill or the like, copper plating 5 for connection to copper foils 1 and 2 is applied to the inner wall surface of hole 4 as shown in FIG. 1B. Next, as shown in FIG. 1C, the copper foils 1 and 2 on both sides are patterned by a usual photo-etching process to form leads 1 'and 2' (electric circuit). Although this process example is a method for manufacturing a double-sided circuit board, the same applies to a multilayer circuit board, and the above-described perforation process and copper plating process are used.

[0005]

In such a conventional manufacturing method, thousands of holes must be formed in a lead group forming an electric circuit without burrs. Further, in some cases, surface treatment (smear treatment) of the hole wall must be performed, and a great deal of man-hour is required for interlayer connection, which is a major factor in cost increase. Furthermore, since a through hole is opened in the surface of the substrate, and electronic components cannot be mounted thereon, it becomes a major obstacle to high-density mounting.

Further, since it is not possible to connect the layers at a narrow pitch, there is a problem that it is difficult to effectively utilize the technology for forming an electric circuit at a high density.

The applicant has already proposed, in Japanese Patent Application No. Hei 8-91417, an interlayer connection structure that can achieve connection between leads without piercing the leads on the printed circuit board.

This prior invention is an interlayer connection structure in which a bent portion which protrudes into the insulating layer from one or both of the leads facing each other with an insulating layer forming a circuit board interposed therebetween to connect the leads. Compared with an interlayer connection structure via a through hole, the structure can be simplified, the connection work can be saved, and a large cost reduction can be expected.

In addition, the present invention can be properly implemented even when the leads on the insulating layer forming the circuit board are fine and have a narrow pitch.
Therefore, the problem of the interlayer connection structure by the through hole can be eliminated.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a large number of bent portions can be easily and precisely press-formed on a lead group (electric circuit) on a circuit board at a time. Accordingly, it is an object of the present invention to provide a press mold having a stamping projection capable of effectively enjoying the advantages of the above-mentioned prior invention, and a method of manufacturing the press mold.

This press-molding die has, on the surface of a base made of a metal plating layer, embossing projections formed by plating a part of the plating layer or a hard metal different from the plating layer.

A back-up material is attached to the surface of the plating layer opposite to the surface on which the embossing projections are formed to add strength.

[0013] The press forming die includes a step of forming a large number of recesses on the surface of the metal plate, a step of forming a plating layer on the surface of the metal plate where the recesses are opened, and the step of forming the plating layer by the recesses. It is manufactured by a method including a step of molding a projection for embossing at a part of the metal layer and a step of peeling the plating layer from the metal plate together with the projection for embossing.

[0014]

2 and 3 show the embossing projection 4 described above.
Shows a press mold 1 provided with a large number of. As shown in FIG. 2, the press mold has a sheet-like base 2 formed of a metal plating layer 3 and has a large number of embossing projections 4 protruding from one surface of the plating layer 3. ing.

The embossing projections 4 are formed by metal plating. As an example, as shown in FIG. 2, the embossing protrusions 4 are formed on a part of the plating layer 3 on the surface of the plating layer 3 forming the base 2. Therefore, the plating layer 3 and the embossing projection 4 are formed of the same metal, and nickel plating (nickel alloy plating) as a suitable material.

As another example, as shown in FIG. 3, an embossing projection 4 'formed of a hard metal different from the plating layer is provided on the surface of the plating layer 3 forming the base 2. This embossing projection 4 'is made of, for example, nickel or a nickel alloy,
The plating layer 3 is made of copper or a copper alloy.

The plating layer 3 can be a composite plating layer. That is, a second plating layer can be formed on the surface of the first plating layer to form a composite plating layer.

As shown in FIG. 4, a backup material 5 can be attached to the surface of the plating layer 3 shown in FIGS. 2 and 3 opposite to the surface on which the embossing projections are formed.

The backup material 5 has a function of imparting strength to the plating layer 3 and the embossing projections 4 and 4 ′ to maintain flatness. Stainless steel is used as a suitable material for the backup material 5.

Next, a method for manufacturing the press-molding die 1 having the embossing projections 4 will be described with reference to FIG. As shown in FIG. 5A, a recess 8 is formed on the surface of the metal plate 6 using a punch 7. A suitable material for the metal plate 6 is a stainless steel plate. The punch 7 has a sharp end 9 at the tip. The sharp end 9 of the punch 7 is vertically driven into the surface of the metal plate 6 to form a recess 8 having the same shape as the sharp end 9.

Next, as shown in FIG. 5B, a plating layer 3 is formed on the surface of the metal plate 6 where the recess 8 opens, and at the same time, a part of the plating layer 3 is immersed in the recess 8. The embossing projections 4 are formed. That is, a part of the plating layer 3 is grown in the recess 8 to form the embossing projection 4.

Next, as shown in FIG.
Together with the embossing projections 4 from the surface of the metal plate 6. The press forming die 1 thus formed is a press forming die in which the plating layer 3 and the stamped projections 4 formed by plating are made of the same metal as shown in FIG.

The sharp end 9 of the punch 7 forming the recess on the surface of the metal plate 6 has a conical or frusto-conical shape, and forms a recess 8 having the same shape. For example, the sharp end 9 has a truncated conical shape, and fine irregularities 10 are formed on the distal end surface of the sharp end 9 as shown in FIG. 7A.

The recess 8 formed by the punch 7 shown in FIG. 7A has a plurality of fine irregularities formed on the inner bottom surface thereof. Has a plurality of irregularities 11, and the irregularities 11
Thus, the leads can be soundly connected.

As shown in FIG. 7B, the sharp end 9 of the punch 7 can be formed into a triangular prism having a sharp ridge 12. With the use of the punch 7, the embossing projection 4 is formed into a triangular prism shape having a sharp ridge, and the connection between the leads can be achieved by the sharp ridge 12.

FIG. 6 shows a method of forming an interlayer connection structure on a circuit board 14 using the press mold 1 having a large number of the embossing projections 4.

The circuit board 14 has fine and fine-pitch leads 20 and 21 adhered to one surface and the other surface of the insulating layer 15 to form an electric circuit.

As shown in FIG. 6A, the press-forming die 1 in which the embossing projections 4 are formed by plating on the surface of the plating layer 3.
Using a conductive foil 1 adhered to one surface of the insulating layer 15
8 is embossed by the projection 4 to form a projecting portion 17 on the conductive foil 18 while projecting the projecting 4 into the insulating layer 15 and projecting into the insulating layer. Connect to foil 19. Therefore, an interlayer connection structure is formed. Conductive foil 1
The suitable material for 8, 19 is copper foil.

In this case, the insulating layer 15 forming the circuit board 14 uses a thermoplastic resin sheet, and the press mold 1 is pressed by the projections 4 while being heated by a heater. This allows the local portion of the conductive foil 18 to protrude into the insulating layer 15 while the insulating layer 15 is softened by the protrusions 5.

Next, as shown in FIG.
8 and 19 are patterned by etching to form leads 20 and 21 for electric circuits. As shown in FIGS. 6A and 6B, as an example of electrically connecting the leads 20 and 21 via the bent portions 17, a conductive paste 22 is previously provided on a bonding surface of the conductive foil 19 to the insulating layer 15. Place
A method in which the top of the bent portion 17 is connected to the conductive foil 19 via the conductive paste 22 can be adopted. The conductive paste 22 is heated by the bent portion 17 to achieve a robust connection.

After forming the electric circuit shown in FIG. 6B, the bent portions 17 are attached to the leads 20 and 21 forming the electric circuit.
Is formed to connect the leads 20 and 21, thereby forming an interlayer connection structure.

The leads 20 and 21 are very fine and have a narrow pitch.
50 μm, base 20-100 μm, pitch between projections 30
It is required to have a fine pitch of about 200 μm and a narrow pitch.

The above-mentioned Japanese Patent Application No. Hei 8-91417 shows the configuration shown in FIG.
Shows a press mold with a stamping protrusion.
A means for effectively forming fine and narrow pitch embossing projections has not been solved.

The present invention relates to a press forming die 1 by a plating method.
By forming the base 2 and the embossing projections 4, the projections 4 can be formed easily with high precision.
As a result, the protruding portion 17 for interlayer connection can be formed with high precision to achieve highly reliable interlayer connection.

In addition, the bent portion 17 can be easily and properly formed even when the leads forming the electric circuit are narrow and fine, and can effectively cope with the high density of the electric circuit. Thus, the simplification of the interlayer connection structure can be achieved, and the cost can be reduced.

[Brief description of the drawings]

FIGS. 1A, 1B and 1C are enlarged cross-sectional views showing a method of forming an interlayer connection structure on a conventional circuit board in the order of steps.

FIG. 2 is an enlarged cross-sectional view of a press mold having a stamping protrusion according to the present invention.

FIG. 3 is an enlarged sectional view showing another example of the press mold.

FIG. 4 is an enlarged sectional view showing still another example of the press mold.

FIGS. 5A, 5B, and 5C are enlarged cross-sectional views showing a method of manufacturing the press mold in the order of steps.

FIGS. 6A and 6B are enlarged cross-sectional views showing a method of connecting layers between circuit boards using the press mold in the order of steps.

7A is a side view showing an example of a shape of a punch used for manufacturing the press mold shown in FIG. 5 and an enlarged sectional view showing a stamping protrusion formed using the punch. FIG. 7B is another shape of the punch. FIG. 2 is an enlarged perspective view showing an example and an enlarged sectional view showing an embossing projection formed using the example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Press molding die 2 Base 3 Plating layer 4, 4 'Embossing projection 5 Backup material 6 Metal plate 7 Punch 8 Concave 9 Sharp end 10, 11 Irregularity 13 Ridge 14 Circuit board 15 Insulating layer 17 Projection 18, 19 Conductive foil 20, 21 Electrical circuit leads 22 Conductive paste

Claims (4)

[Claims] 1. A press-molding die having a stamping projection formed on a surface of a base made of a plating layer by plating growth. 2. The press-molding die according to claim 1, wherein said embossing projection is formed by a part of a plating layer forming said base. 3. The press-molding die according to claim 1, wherein a backup material is bonded to a surface of the plating layer opposite to a surface on which the embossing projections are formed. 4. A step of forming a plurality of recesses on a surface of a metal plate, forming a plating layer on a surface of the metal plate where the recesses are opened, and simultaneously forming a mold with a part of the plating layer by the recesses. A method for producing a press-molding die having a stamping projection, comprising a step of forming a stamping projection and a step of peeling the plating layer from the metal plate together with the stamping projection.