JP2000133944A - Manufacture of laminated wiring board and wiring board with bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method suitable for effectively manufacturing a fine laminated wiring board and a wiring board with bumps of high density. SOLUTION: A wiring pattern 6 is formed on either of two wiring boards 11 that are laminated together, metal foil pieces 15 blanked out of a low-melting metal foil 14 by a punching machine 12 are temporarily fixed at prescribed positions on the wiring pattern 6, and the metal foil pieces 15 are melted by heating into spherical bodies 16 due to surface tension when they are melted. After the spherical bodies 16 are cooled down, an adhesive layer 17 is formed on the wiring pattern 6, the other wiring board 11 is laminated thereon, and the wiring boards 11 and 11' are thermocompressed into a laminate of integral structure. As a result, the wiring boards 11 and 11' are formed into a laminate of integral structure where the wiring patterns 6 and 10' are electrically connected together through the spherical bodies 16, whereby a prescribed laminated wiring board can be obtained. If manufacturing processes are finished at a stage where the spherical bodies 16 are formed, a wiring board with bumps where the spherical bodies 16 serve as electrode bumps can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a laminated wiring board and a wiring board with bumps, and more particularly to a method of manufacturing a laminated wiring board having a fine wiring structure and a wiring board with bumps.

[0002]

2. Description of the Related Art As a conventional laminated wiring board, for example, a wiring board based on a hard substrate such as an epoxy resin reinforced with glass fiber and a highly flexible film-like material such as a polyimide film are used as base materials. Wiring boards are known.

In the former method, electrical conduction between layers in a laminated wiring board is generally based on drilling. On the other hand, the latter method is based on laser drilling. I have. In each case,
A plating film is formed inside the formed hole, and thereby electrically connects the wiring patterns of the stacked wiring boards.

However, according to these methods, for example, in the former case, the minimum hole diameter that can be formed by a drill is limited to 0.1 mm, and therefore, it is inferior in fineness. It is difficult to deal with higher densities. Also, drilling with a drill has difficulties in securing the positional accuracy of the holes, and also has the disadvantage of generating machining residues.

[0005] The latter laser drilling enables precision processing, and thus can cope with the demand for higher density of the laminated wiring board, but has a unique disadvantage of laser processing. Laser drilling is expensive in laser processing machines, has poor processing efficiency, and has the property of generating residues due to evaporation of the base material in the laser-processed portion, which adversely affects subsequent plating film formation. Strong tendency to exert.

In the case of a method using laser processing,
Since the film to be subjected to laser processing (in many cases, a polyimide film) is inactive, there is a side surface that makes it difficult to form a plating film on the holes. Therefore, a special plating apparatus is required. The financial burden of this cannot be ignored.

Further, according to these conventional methods, there is a problem of plating treatment as a problem common to the hard laminate and the flexible laminate. Generally, the formation of a plating film in a hole is performed by electroless copper plating, and the plating solution used for this plating treatment contains formalin which may affect health.

Therefore, as a method for solving this problem, a conduction method using a silver paste which does not require electroless plating has been proposed. The silver paste is raised by printing at a predetermined position of the wiring pattern of the wiring board on one side of the wiring boards to be laminated, and then the other is passed through a thin insulating plate having holes formed at the predetermined position. The hole is filled with silver paste by laminating the wiring board on the side of, and the filled silver paste is used to conduct between the wiring patterns, promising as a method that does not require electroless copper plating treatment Have been watched.

[0009]

However, according to the method using this silver paste, it is necessary to repeat printing four or five times in order to build up a sufficient amount of silver paste on the wiring pattern. Efficiency is poor, and there is a limit to the fineness due to the use of a print mask, and poor conduction of holes formed in the insulating plate may lead to poor conduction.

Further, in addition to these, there are many problems that need to be solved, such as printing misregistration, fluctuations in printing accuracy due to an increase in the viscosity of the resist, and variations in the degree of swelling of the silver paste. It can not be said.

Therefore, an object of the present invention is to provide excellent fineness and workability, do not require expensive equipment such as a laser processing machine, and have no instability factors such as a silver paste printing method. It is an object of the present invention to provide a method of manufacturing a laminated wiring board which does not require electroless copper plating to conduct between wiring patterns.

Another object of the present invention is to efficiently manufacture a laminated wiring board having fineness, and further to another wiring board such as a printed board, or another electric component such as a semiconductor chip. It is an object of the present invention to provide a method for manufacturing a wiring board with a high-density bump suitable for use in bonding with a wiring board.

[0013]

According to the present invention, in order to achieve the above object, a plurality of wiring boards having a predetermined wiring pattern formed on a surface thereof are laminated, and a space between the wiring patterns of the plurality of wiring boards is provided. In a method of manufacturing a multilayer wiring board for manufacturing a multilayer wiring board that is electrically conducted, a metal piece is supplied to a predetermined portion of the wiring pattern of the wiring board on either side of the plurality of wiring boards, and By heating and melting the piece, a sphere based on the metal piece utilizing surface tension at the time of heating and melting was generated on the wiring pattern of the wiring board on either side, and the sphere was cooled and solidified. Thereafter, an adhesive layer is formed on a wiring pattern of the wiring board on one side of the plurality of wiring boards, and a wiring board on the other side of the plurality of wiring boards is placed on the adhesive layer and pressed. By doing so, the one side of the wiring board There is provided a method for manufacturing a laminated wiring board, wherein the inter-wiring pattern of a wiring board of the other side be electrically conducted through the spheroids.

Further, in order to achieve the above object, the present invention has a spherical bump on a wiring pattern of a wiring board which is joined to another wiring board or another electric component such as a semiconductor chip. In the method of manufacturing a wiring board with bumps for manufacturing a wiring board with bumps, a low-melting metal piece is supplied to a predetermined portion of the wiring pattern of the wiring board, and the low-melting metal piece is heated and melted to obtain a surface tension. The present invention provides a method for manufacturing a wiring board with bumps, characterized in that the spherical bump is formed on the basis of the above.

As the above-mentioned wiring board, for example, a copper or copper alloy foil is laminated on the surface of a synthetic resin plate such as an epoxy resin reinforced with glass fiber, and the foil is subjected to an etching process. A hard wiring board having a wiring pattern formed thereon, or a flexible film-shaped wiring board having a wiring pattern formed on a surface of an insulating film such as a polyimide film in the same manner is used.

In many cases, the wiring of these wiring boards in the laminated wiring board is performed between hard wiring boards or between film wiring boards. If necessary, different wiring boards may be combined. When viewed from the film wiring board,
Since the combination with the hard wiring board has a reinforced form, it is effective in widening the utilization range of the film-shaped wiring board, which tends to be restricted in use because of its flexibility.

The formation of the wiring pattern on the wiring board is performed on one side,
Alternatively, both sides may be used. The number of stacked wiring boards is 2
There are no particular restrictions on the number of layers, such as three, four, or the like. In addition, a configuration may be adopted in which conduction between wiring patterns is performed only between specific adjacent wiring boards among multilayered wiring boards, and other wiring boards are only laminated.

As the constituent material of the low melting point metal piece, a metal that can be heated and melted within the heat resistance limit of the wiring board is used. Therefore, the low melting point of the low melting point metal piece means the low melting point in this sense. means. Specifically, for example, a tin-lead alloy or a metal piece based on this is used,
In addition, this metal piece, from the point of speeding up heating and melting,
In many cases, it is configured as a foil.

The constituent material of the adhesive layer is preferably a liquid crystal polymer which exhibits adhesiveness by heating and melting, and specifically, a liquid crystalline aromatic polyester resin, a liquid crystalline aromatic polyamide resin, or a liquid crystalline polymer. A polyimide resin or the like is used.

As a means for supplying a metal piece to a predetermined portion of the wiring pattern, a tacking method using a punching machine is effective. It is desirable to press the metal pieces punched by the puncher of the punching machine against the wiring pattern of the wiring board located below the punching machine and temporarily attach the metal pieces.As a result, the preparation of the metal pieces and the temporary attachment are performed simultaneously. Thus, efficient work can be performed. If the configuration is such that the long metal piece raw material is prepared by winding it on a reel or the like, and the wiring board is continuously supplied to the punching machine, the working efficiency will be further improved.

When a material that exhibits an adhesive action by being melted by heat is selected as the adhesive layer, heat is required for pressurizing after laminating the wiring boards. For example, softness is required at room temperature. In the case of selecting a material having such a property that it is hardened by heating after lamination and pressing, or standing at room temperature, heat at the time of pressing is not necessarily required.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for manufacturing a laminated wiring board and a wiring board with bumps according to the present invention will be described. FIGS. 1A to 1I show the manufacturing procedure in order.

(A) is a laminate 4 composed of a polyimide film 1 having a thickness of 50 μm and copper foils 2 and 3 having a thickness of 18 μm laminated on both sides of the film 1.
Is shown. The polyimide film 1 in the laminate 4 is formed by casting on one of the surfaces of the copper foils 2 and 3 and then laminated on the other copper foil via an adhesive (not shown). It is configured.

(B) shows the copper foil 2 on one side of the laminate 4
Shows the etching process for
m circular openings 5 are formed in the copper foil 2.

(C) shows a step of making a hole in the polyimide film 1, and carbon dioxide laser processing is performed using the copper foil 2 as a mask material. Thus, the polyimide in the portion of the opening 5 is removed, and the blind via hole 7 is formed.

(D) is a step of forming a conductive film for the blind via hole 7, and 8 is a formed copper conductive film. By forming the conductive film 8, the copper foils 2 and 3 are electrically connected.

(E) shows a photo-etching step, in which a wiring pattern 6 having a predetermined shape is formed from the copper foil 2, whereby the conductive film 8 also becomes a member of the wiring pattern 6. On the other hand, the copper foil 3 is also etched at the same time, whereby a wiring pattern 10 having a predetermined shape is formed. Thus, the preparation of the wiring board 11 on one side is completed.

(F) shows a step of temporarily attaching a metal foil piece to the wiring pattern 6, in which the punching machine 12 is disposed above, and the wiring board 11 is arranged below the punching machine 12 at a predetermined pitch. It is configured to move in the direction of the arrow.

A puncher 13 of a punching machine 12 punches a metal foil piece 15 into a circular shape having a diameter of 100 μm from a low-melting metal foil 14 having a thickness of 10 μm and made of a tin-lead alloy. The punched metal foil pieces 15 are pressed against the conductive film 8 during the extension of the punching operation of the puncher 13, and are thereby temporarily attached to predetermined portions of the wiring pattern 6.

(G) shows a step of heating and melting the metal foil piece 15. The wiring board 11 to which the metal foil pieces 15 are temporarily attached is
The metal foil piece 15 is heated to a melting point or higher in a heating furnace in a nitrogen atmosphere and reflowed. As a result, the metal foil piece 15 that has been heated and melted rises into a spherical shape due to its own surface tension, and is then cooled into a spherical object 16.

(H) shows a step of forming an adhesive layer,
Indicates an adhesive layer of a liquid crystal polymer of a heat melting type formed on the wiring pattern 6. The adhesive layer 17 is provided so that the upper part of the spherical object 16 is exposed.

(I) shows a laminating step. (H) Wiring board 11 on one side with adhesive layer 17 formed on the surface
And a wiring board 11 'on the other side separately manufactured through the steps (a) to (e) (the same numerals as the numbers on the wiring board 11 indicate the same parts and are indicated with "'"). Are prepared and laminated on each other.

Next, the laminated wiring boards 11 and 11 'are heated and pressed in a press, whereby the spherical object 16 is brought into contact with a predetermined portion of the wiring pattern 10' of the wiring board 11 '. At the same time, the wiring boards 11 and 11 ′ are bonded by the hot-melt bonding layer 17. As a result, the wiring patterns 6 and 10 ′ are electrically conducted through the spherical object 16, thereby forming a laminated wiring board having a predetermined structure.

FIG. 2 shows another embodiment of the method for manufacturing a laminated wiring board and a wiring board with bumps according to the present invention. (A) to (f) are the same as those in FIG. 1, and thus description thereof will be omitted, and only the steps after (g) will be described.

In the step (g), after the metal foil piece is heated and melted to form a spherical body 16 on the wiring pattern 6, the other wiring board 11 separately prepared as shown in (h). Adhesive layer 17 on the surface of the wiring pattern 10 '
Is formed, and then the wiring board 1 thus prepared
1, 11 'are laminated together.

(I) is the laminated structure of the wiring board 1
This shows a structure in which the adhesive layer 1 'and the spherical object 16 of the wiring board 11 are laminated so as to face each other, and these are heated and pressed. The sphere 16 breaks through the adhesive layer 17 that has been heated and melted by being pressed, and comes into contact with the wiring pattern 10 ′ of the wiring board 11 ′.

As a result, the wiring boards 11 and 11 'are
7, and the blind via holes 7 of the laminated board 11 are filled with an adhesive layer 17,
Further, since the wiring patterns 6 and 10 'are electrically connected by the sphere 16, a predetermined laminated wiring board is constructed. This embodiment differs from FIG. 1 in that an adhesive layer 17 is formed on the other wiring board 11 'side.

FIG. 1 (g) in FIG. 1 and FIG. 2 constitutes a substrate for manufacturing a laminated wiring board in the subsequent steps, but can be used for other purposes. That is, the spherical object 16 in (g) can be used as an electrode bump.
This embodiment can be used as a wiring pattern of another wiring board such as a printed circuit board or a wiring board for bonding with another electric component such as a semiconductor chip.

The spherical bump (spherical object 16)
Are formed on the basis of the surface tension of the metal foil pieces 15 by heating and melting, so that the arrangement can be made finer, and therefore, it is possible to provide a wiring board with bumps having a high-density structure. Can be.

[0040]

As described above, according to the method for manufacturing a laminated wiring board and a wiring board with bumps according to the present invention, in the production of the laminated wiring board, any one of the wiring boards laminated to each other is used. A low-melting metal piece is supplied to a predetermined portion of the wiring pattern of the wiring board on the side, and the low-melting metal piece is heated and melted to generate a spherical material of a low-melting metal piece melt using surface tension. Further, an adhesive layer is formed on the wiring pattern of the wiring board on one side of the wiring boards to be laminated, or on the wiring pattern of the wiring board on the other side, and these wiring boards are laminated and pressurized. Since the wiring patterns of the wiring boards are electrically connected to each other via the spherical body and the wiring boards are bonded and integrated by the adhesive layer, the following advantages can be obtained.

1. Since the continuity between the wiring patterns is performed by a spherical object generated by heating and melting the low melting point metal piece, a thin and fine laminated product according to the size of the low melting point metal piece to be applied can be constructed. For example,
A laminated wiring board optimal for high-density products such as IC cards can be provided. 2. The work efficiency is high because a predetermined laminated wiring board can be manufactured only by heating and melting the low melting point metal piece, forming the adhesive layer, and pressing the laminate. 3. There is no need for expensive equipment such as a laser beam machine. 4. Since the size and height of the spherical object can be made uniform by making the size of the low melting point metal piece constant, there is no factor of instability with accuracy as in the silver paste printing method. 5. Electroless plating is not required to conduct between the wiring patterns.

On the other hand, in the production of a wiring board with bumps, a low-melting metal piece is supplied to a predetermined portion of a wiring pattern of the wiring board, and this is heated and melted to form a spherical bump as an electrode. Therefore, it is possible to manufacture a wiring board with high-density bumps in which small bumps are finely arranged.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a method for manufacturing a laminated wiring board and a wiring board with bumps according to the present invention, and (a).
(I) shows the manufacturing procedure.

FIG. 2 is an explanatory view showing another embodiment of the method for manufacturing a laminated wiring board and a wiring board with bumps according to the present invention;
(A)-(i) show the manufacturing procedure.

[Explanation of symbols]

 1, 1 'polyimide film 2, 3 copper foil 4 laminated film 5 circular opening 6, 6', 10, 10 'wiring pattern 7, 7' blind via hole 8, 8 'conductive film 11, 11' wiring board 12 punching machine 13 puncher 14 low melting point metal foil 15 metal foil piece 16 spherical object 17 adhesive layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference)

Claims (8)

[Claims] 1. A laminated wiring board for producing a laminated wiring board in which a plurality of wiring boards having a predetermined wiring pattern formed on a surface thereof are laminated, and the wiring patterns of the plurality of wiring boards are electrically connected to each other. In the manufacturing method, a low-melting-point metal piece is supplied to a predetermined portion of the wiring pattern of the wiring board on either side of the plurality of wiring boards, and the low-melting-point metal piece is heated and melted, whereby A sphere based on the low melting point metal piece utilizing surface tension during heating and melting is generated on the wiring pattern of the side wiring board, and after the sphere is cooled and solidified, one of the plurality of wiring boards is formed. Forming an adhesive layer on the wiring pattern of the wiring board on the other side, placing the wiring board on the other side of the plurality of wiring boards on the adhesive layer, and applying pressure to the wiring board on the one side. And the wiring pattern of the wiring board on the other side. A method for manufacturing a laminated wiring board, wherein electrical connection is made between the balls through the spherical object. 2. The method according to claim 1, wherein said low melting point metal piece is a tin-lead alloy or a metal based on said alloy. 3. The method according to claim 1, wherein the low-melting point metal piece is a foil. 4. The circuit according to claim 1, wherein the adhesive layer is formed on a wiring pattern of the wiring board on which the spherical object is formed. A method for manufacturing a laminated wiring board. 5. The laminate according to claim 1, wherein the adhesive layer is formed on a wiring pattern of the wiring board on which the spherical object is not formed. Manufacturing method of wiring board. 6. The method according to claim 1, wherein the adhesive layer is a liquid crystal polymer. 7. The low melting point metal piece is punched by a puncher of a punching machine provided on the one side wiring board, and the puncher removes the punched low melting point metal piece from the one side. The method for manufacturing a laminated wiring board according to any one of claims 1 to 6, wherein the temporary mounting is performed by pressing the wiring pattern on a predetermined portion of the wiring board. 8. A bumped wiring board for manufacturing a bumped wiring board having a spherical bump to be joined to another wiring board or another electrical component such as a semiconductor chip on a wiring pattern of the wiring board. In the method, a low melting point metal piece is supplied to a predetermined portion of the wiring pattern of the wiring board, and the low melting point metal piece is heated and melted to form the spherical bump based on its surface tension. Manufacturing method of a wiring board with a wire.