JPH08125331A - Manufacture of printed circuit board - Google Patents

Abstract

PURPOSE: To manufacture a printed circuit board which can package wirings of higher density by a simple process with high reliability by high yield. CONSTITUTION: The method for manufacturing a printed circuit board comprises the steps of extruding or dropping melted conductor on a predetermined region surface of a sheetlike or platelike support base material 3, then solidifying to form protruding conductive bump 5 group, sequentially superposing to laminate a synthetic resin sheet 6 and a conductive metal layer 3' on the surface formed with the bump 5 group, and pressurizing the laminate to pass the end of the bump 5 group in the thickness direction of the sheet 6 to connect it to the layer 3'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a simple method for manufacturing a printed wiring board having connecting wiring portions in the thickness direction.

[0002]

2. Description of the Related Art For example, in a double-sided printed wiring board or a multi-layered printed wiring board, wiring patterns are electrically connected as follows. That is, in the case of a double-sided printed wiring board, perforation processing (perforation processing) is performed at a predetermined position on the double-sided copper foil-clad laminate, and chemical plating treatment is applied to the entire surface including the inner wall surface of the perforated holes. After that, it is thickened by an electroplating process to increase the reliability by thickening the metal layer on the inner wall surface of the hole to establish electrical connection between the wiring pattern layers.

Further, in the case of a multilayer printed wiring board, after patterning the copper foils stretched on both sides of the laminated board respectively, the copper foils are laminated and arranged on the patterned surface via an insulating sheet (for example, prepreg). After integrating by heating and pressurizing, as in the case of the above-mentioned double-sided printed wiring board, while making electrical connection between the wiring pattern layers by punching and plating, the surface copper foil is patterned. , A multilayer printed wiring board is obtained. In the case of a multilayer printed wiring board having more wiring layers, it can be manufactured by a method of increasing the number of double-sided printed wiring boards inserted in the middle.

In the method of manufacturing a printed wiring board described above, as a method of electrically connecting the wiring pattern layers without depending on the plating method, a hole is made at a predetermined position of a double-sided copper foil-clad substrate, and a conductive paste is placed in the hole. There is also a method in which the resin layer of the conductive paste poured into the holes is cured by a printing method or the like to electrically connect the wiring layers.

[0005]

As described above, in the method of manufacturing a printed wiring board which utilizes the plating method for the electrical connection between the wiring pattern layers, the electrical connection between the wiring layers is made in the laminated board. There is a drawback that the manufacturing process of the printed wiring board is redundant and the process control is complicated, since it requires drilling (drilling) processing, plating process including the inner wall surface of the hole. On the other hand, the method of embedding a conductive paste in the holes for electrical connection between the wiring layers by printing or the like also requires a drilling step as in the case of the plating method. Moreover, it is difficult to pour the conductive paste evenly (uniformly) into the bored holes and to embed it, and there is a problem in the reliability of electrical connection. In any case,
The need for the perforating step is reflected in the cost and yield of the printed wiring board, and there is a drawback that it is not possible to meet the demand for cost reduction.

Further, in the case of the connection structure between the wiring pattern layers, since the conductor holes for connecting the wiring pattern layers are provided on the front and back surfaces of the printed wiring board, the wiring pattern is formed in the region of the conductor holes. It cannot be formed / arranged, and electronic parts cannot be mounted. This poses a problem that the improvement of the wiring pattern density is restricted and the improvement of the mounting density of electronic components is also hindered. In other words, it cannot be said that the printed wiring board obtained by the conventional manufacturing method can sufficiently meet the demands for high-density wiring and compact circuit devices by high-density mounting, and further miniaturization of electronic devices. Including the above, a more practically effective method for producing a printed wiring board is desired.

The present invention has been made in view of the above circumstances, and provides a method capable of manufacturing a highly reliable printed wiring board with a high yield, which enables wiring and mounting at a higher density by a simple process. To aim.

[0008]

According to a first method for producing a printed wiring board of the present invention, a molten conductive material is extruded or dropped onto a predetermined area surface of a sheet-shaped or plate-shaped supporting substrate. Post-solidifying to form a projecting conductive bump group, a step of stacking a synthetic resin sheet on the surface on which the projecting conductive bump group is formed to form a laminate, and the laminate. And a step of pressing the tip end portion of the conductive bump group having a protrusion shape to penetrate in the thickness direction of the synthetic resin sheet.

A second method for manufacturing a printed wiring board according to the present invention is characterized in that a predetermined area surface of a sheet-shaped or plate-shaped supporting substrate is
A step of forming a projecting conductive bump group by extruding or dropping the melted conductive material and then solidifying it, and a synthetic resin sheet and a conductive film on the surface on which the projecting conductive bump group is formed. A step of sequentially stacking metal layers to form a laminated body, and pressing the laminated body to penetrate the tip end of the projecting conductive bump group in the thickness direction of the synthetic resin sheet to connect to the conductive metal layer. And a process.

A third method for producing a printed wiring board according to the present invention is characterized in that a predetermined area surface of a sheet-shaped or plate-shaped supporting substrate is
A step of forming a projecting conductive bump group by extruding or dropping the melted conductive material and then solidifying it, and a synthetic resin sheet and a conductive film on the surface on which the projecting conductive bump group is formed. A step of sequentially stacking metal layers to form a laminated body, and pressing the laminated body to penetrate the tip end of the projecting conductive bump group in the thickness direction of the synthetic resin sheet to connect to the conductive metal layer. It is characterized by comprising a step and a step of wiring patterning the conductive metal layer.

That is, the present invention is characterized by means for forming a connection wiring portion penetrating the insulating layer. That is, as a connection wiring portion on the surface of the supporting base material, a conductive material that has been melted or fluidized by heating or the like is applied in a projection shape by, for example, an extrusion method through a nozzle or a printing method, Characterized by the step of solidifying this to form a conical, cylindrical, or prismatic conductor, and forming the connection wiring part by penetrating the insulator layer at the tip of this protruding conductor. To be

In the present invention, examples of the supporting base material for forming the conductive bump group include synthetic resin sheets having good releasability, or a conductive sheet (foil), and the supporting base is one sheet. It may be a sheet or may be a wiring pattern, its shape is not particularly limited, and the conductive bump group is formed not only on one main surface but also on both main surfaces. May be used.

Here, the conductive bumps are made of, for example, conductive powder such as silver, gold, copper, solder powder, palladium, or carbon, an alloy powder or a composite (mixed) metal powder of these, and a fluororesin or a polycarbonate resin, for example. , A polysulfone resin, a polyphenylene sulfide resin, a polyester resin, a phenoxy resin, a phenol resin, an epoxy resin, a phenoxy resin, a melamine resin, and a polyimide resin.

As described above, the present invention is characterized by means for forming the conductive bump group with the conductive composition. That is, a conductive composition that is solid at room temperature or solidifies by a drying / curing reaction is used as a starting material,
For example, conical, pyramidal, cylindrical, or prismatic in the molten state or in the fluidized state, for example, by injection / dropping through a nozzle with a diameter of about 0.5 mm, or screen printing with a squeegee. Height 50 ~ 800μ
A projection-like conductive bump of about m 2 is formed on the surface of a predetermined supporting base material. Then, if necessary, for example, an electric heater,
By using an ultrasonic heating device, a CO ₂ laser, or the like as a heat source for heating and drying, for example, a conical or pyramidal conductive bump having a sharp tip is formed. The height of the conductive bump group formed here is generally 100 to
About 400 μm is desirable, and the height of the conductive bump group may be a height capable of penetrating one layer of synthetic resin sheet and a height capable of penetrating a plurality of layers of synthetic resin sheet as appropriate.

In the present invention, examples of the synthetic resin sheet in which the conductive bump group is inserted and through-type wiring connection portions are formed include a thermoplastic resin film (sheet) and its thickness. Is preferably about 50 to 800 μm. Here, examples of the thermoplastic resin sheet include sheets of polycarbonate resin, polysulfone resin, thermoplastic polyimide resin, tetrafluoropolyethylene resin, hexafluoropolypropylene resin, polyetheretherketone resin, and the like. Further, as the thermosetting resin sheet which is kept in the pre-curing state, epoxy resin, bismaleimide triazine resin, polyimide resin, phenol resin, polyester resin, melamine resin, or butadiene rubber, butyl rubber, natural rubber, neoprene rubber, silicone Examples include raw rubber sheets such as rubber. These synthetic resins may be used alone or may contain an insulating inorganic or organic filler, and are a sheet formed by combining with a reinforcing material such as glass cloth or mat, organic synthetic fiber cloth or mat, or paper. It may be.

Further, according to the present invention, when a laminated body in which the principal surface of a synthetic resin sheet is placed in contact with the principal surface of a support base or the like on which the bump group is formed is placed directly or when heated and pressed. As a base (patch plate) on which a synthetic resin sheet is placed, a metal plate or a heat-resistant resin plate with little size or deformation, for example, a stainless plate, a brass plate, a polyimide resin plate (sheet), a polytetrafluoroethylene resin Plates (sheets) are used. When the laminated body is pressed, when the resin group of the synthetic resin sheet is heated to be softened, and the bump group is inserted, better insertion of the bump group can be achieved.

[0017]

According to the method of manufacturing a printed wiring board according to the present invention,
Wiring pattern The wiring connection between layers that electrically connects the layers is formed by the heating and pressurization in the so-called layer-integrating process to plasticize the synthetic resin sheet that forms the interlayer insulating layer, and the supporting substrate surface. By press-fitting the conductive bump group of
A reliable electrical connection between the wiring pattern layers is achieved. In other words, by forming the conductive bump group by dropping and extruding a conductive material that has been melted, etc., the process can be greatly simplified, and at the same time, highly precise, at any position (location) between fine wiring pattern layers. Since a highly reliable electrical connection can be formed, a printed wiring board having a high wiring density can be manufactured at low cost. In addition, since it is not necessary to form connection holes for electrical connection between the wiring pattern layers, a printed wiring board capable of high-density wiring and high-density mounting can be obtained accordingly.

[0018]

Embodiments of the present invention will be described below with reference to FIGS. 1 (a) to 1 (c), 2 (a) to 3 (c) and 3 (a) to 3 (b), respectively.

Example 1 FIGS. 1 (a) to 1 (c) schematically show an example of an embodiment of a method for manufacturing a printed wiring board in this example. First, silver powder 70 having an average particle size of 2 μm is used. A mixture of 1 part by weight and 30 parts by weight of polysulfone resin powder was prepared and heated and melted at about 370 ° C. to obtain a substantially uniform mixed melt. After defoaming this melt, it was placed in a cylinder 1 with a heating device as shown in FIG. 1 (a) and kept at a melting temperature of about 330.degree. Next, the support base material 3 adsorbed and placed on the surface of the support base 2 with the heating device 3, for example, the surface of the copper foil having a thickness of 35 μm, which has been roughened on one side heated and held at about 150 ° C. The bottom surface of the was contacted (adhered). After that, by operating the cylinder 1a of the cylinder 1 with the heating device, the conductive melt 4 is applied to the surface of the copper foil 3 through the through hole 1b having a diameter of about 0.5 mm preformed on the bottom wall surface at 10 kg / cm ²
The conductive bumps (conical bumps) having a bottom diameter of about 0.55 mm and a height of about 0.50 mm were deposited by separating from the copper foil 3 surface at a pressure of about 1 mm / sec. Approximately 5 seconds after the cylinder 1 with the heating device is separated from the surface of the copper foil 3, the formed protruding conductive bumps are solidified, and as shown in a sectional view of FIG. 1 (b), A conical conductive bump group 5 was integrally formed on one main surface (here, a roughened surface).

Copper foil 3 on which the conductive bumps 5 are formed
And a synthetic resin sheet 6, for example, a 100 μm thick polyetherimide resin film (trade name, Sumilite FS-
1400, Sumitomo Bakelite KK) were laminated to sandwich the conductive bumps 5 group. Then, a polyimide resin film is laminated and arranged on the back surface of the copper foil 3 and the synthetic resin sheet 6 as a backing plate, respectively, and a resin pressure of 50 M is applied.
When the film on the front and back sides was peeled off while being pressed with Pa, the conductive bumps 5 were formed in substantially the same shape as shown in the sectional view of FIG. 1 (c).
It was press-fitted into it to obtain a base plate for a printed wiring board in which the tip portion penetrated to form the wiring connection portion 5 '.

On the exposed surface of the wiring connection portion 5'of this base plate for a printed wiring board, patterning is performed by printing and drying a silver paste, while patterning is performed on the copper foil 3 surface.
A printed wiring board was manufactured. Next, the penetration type wiring connecting portions 5'provided in this printed wiring board were subjected to a continuity test from the front and back sides of each wiring connecting portion 5'with a tester, and the total resistance was 0.01 Ω or less.

In the above, when the temperature of the molten conductor 4 housed in the heating device-equipped cylinder 1 is set to 330 ° C. when the conductive bumps 5 are formed by extrusion, the bottom diameter is about 0.6 mm, and A protruding conductive bump (conical bump) having a size of about 0.35 mm was deposited. In addition, the molten conductive material 4 held at about 330 ° C was repeatedly printed several times through a screen plate made of a metal plate having a hole of 0.35 mm in diameter at a required position, and a conical shape with a height of about 300 μm was printed. The same printed wiring board was obtained when the conductive bump group of was formed.

Example 2 FIGS. 2 (a) to 2 (c) schematically show an embodiment of this example. In the case of Example 1, the conductive bumps (conical shape) Bumps)
It is partly modified as follows. That is, the supporting base material 3, which is adsorbed and placed on the surface of the supporting base 2 with the heating device 3,
For example, the conductive melt 4 is extruded at a pressure of about 10 kg / cm ² and a speed of 1 mm / sec onto a copper foil surface having a thickness of 35 μm, which has been roughened on one side and heated and held at about 150 ° C. When depositing a conductive bump (conical bump), first, the conductive melt 4 is swollen in the opening of the through hole 1b of the bottom wall of the cylinder 1 with a heating device, and then the swollen portion is made of copper. Foil 3
It comes in contact with the surface and pulls it apart, the maximum diameter of the bottom is about 0.70 mm,
A group of protruding conductive bumps (conical bumps) having a height of about 0.70 mm were deposited.

Next, as shown in a sectional view in FIG.
A copper foil 3 on which the conductive bumps 5 are formed, a synthetic resin sheet 6, for example, a 100 μm thick polyetherimide resin film (trade name, Sumilite FS-1400, Sumitomo Bakelite KK), and one surface is roughened. The copper foil 3'having a thickness of 35 .mu.m was laminated. After that, polyimide resin films were laminated and arranged as backing plates on the back surfaces of the copper foil 3 and the copper foil 3 ', respectively, and taken out with a resin pressure of 50 MPa, and the front and back films were peeled off.
As shown in a sectional view in FIG. 2B, the conductive bumps 5 are formed.
A double-sided copper-clad laminate for a printed wiring board was obtained, in which the group was formed as it was, and was press-fitted into the synthetic resin sheet 6 to form a wiring connection portion 5'through which the tip portion penetrates.

After that, a normal etching resist ink (trade name, PSR-4000 H, Taiyo Ink KK) was screen-printed on both copper foils 3, 3'of the double-sided copper-clad laminate for printed wiring board to obtain a conductor. After masking the pattern portions 3a and 3a ', after performing an etching treatment with cupric chloride as an etching solution, the resist mask was peeled off to obtain a double-sided printed wiring board 7 as shown in cross section in FIG. 2 (c). . When the thus-produced double-sided printed wiring board was subjected to an electrical check that is usually carried out, no problems such as defects or reliability were found in all connections. In addition, in order to evaluate the reliability of the connection between the double-sided conductive patterns, a hot oil test was conducted (immersion in oil at 260 ° C for 10 seconds, in oil at 20 ° C.
No occurrence of defects was observed even after 500 cycles of 20 seconds immersion cycle (1 cycle), and the connection reliability between conductive (wiring) pattern layers was remarkably superior to that of the conventional copper plating method. It was

Example 3 FIGS. 3 (a) and 3 (b) schematically show an embodiment of this example. That is, this is an example of manufacturing a multilayer printed wiring board by combining the copper foil 3 having the conductive bumps 5 formed in the second embodiment and the double-sided printed wiring board 7.

First, as shown in a sectional view in FIG. 3 (a), roughening is performed on both sides of the double-sided printed wiring board 7 with a synthetic resin sheet 6, for example, a polyetherimide resin film having a thickness of 100 μm. A 35 μm-thick copper foil 3 having a conductive bump 5 group deposited on the treated surface was laminated. Then, polyimide resin films were laminated and arranged as backing plates on the back surfaces of the copper foils 3 on both sides, and the films were taken out with the resin pressure being applied at 50 MPa, and the front and back films were peeled off, as shown in FIG. 3 (b). As shown in a sectional view in FIG. 3, the conductive bumps 5 are formed in substantially the same shape, and are press-fitted into the synthetic resin sheet 6 so that the tip portions thereof penetrate to electrically connect to the double-sided printed wiring board 7. A double-sided copper-clad laminate 8 for a multilayer printed wiring board having a configuration in which the wiring connection portion 5'is configured is obtained.

Then, ordinary etching resist ink is screen-printed on both surfaces of the copper foil 3 of the double-sided copper-clad laminate for a multilayer printed wiring board to mask the conductor pattern portion, and then cupric chloride is used as an etching solution. After the etching treatment, the resist mask was peeled off to obtain a multilayer printed wiring board. When the thus-produced multilayer printed wiring board was subjected to an electrical check which is usually carried out, no problems such as defects or reliability were found in all the connections.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. For example, in the above, 70 parts by weight of the conductive bumps and silver powder with a fen particle size of 2 μm and polysulfone resin powder are used.
Although it was formed in a mixed system with 30 parts by weight, the composition ratio is, for example, 40 to 90 parts by weight of silver powder and 60 to 10 parts of polysulfone resin powder.
It can be selected within the range of parts by weight, and polystyrene resin powder or the like can be used instead of the polysulfone resin. Further, as the synthetic resin sheet, for example, a glass / epoxy resin prepreg may be used.

[0030]

As can be seen from the above description, according to the method for manufacturing a printed wiring board of the present invention, the step of forming the conductive bump group for connecting the wiring pattern layers and the synthetic resin sheet are laminated. In this way, it is possible to easily manufacture a double-sided printed wiring board or a multi-layered printed wiring board while reducing the number of manufacturing steps, such as the step of hot pressing and the step of patterning the outer layer, as compared with the conventional manufacturing method. It will be possible. Particularly in the production of a multilayer printed wiring board in which many steps are repeated, the number of steps is significantly reduced, which is effective in improving productivity or mass productivity. Further, in the manufacturing process of the conventional multilayer printed wiring board and the like, since the drilling process and the plating process, which are indispensable, are no longer necessary, the defects occurring in the manufacturing process are significantly suppressed, and the yield is improved. Not only that, a highly reliable printed wiring board can be obtained. Further, since the printed wiring board manufactured does not have holes for interlayer connection on the surface, the wiring density can be significantly improved, and the mounting area for electronic components can be set regardless of the positions of the holes. As a result, the packaging density can be remarkably improved, and the distance between the mounted electronic components can be shortened, so that the circuit performance can be improved. That is, it can be said that the present invention not only contributes to the reduction of the cost of the printed wiring board, but also contributes to the downsizing of the mounted circuit device and the high performance thereof.

[Brief description of drawings]

FIG. 1 schematically shows an embodiment of the present invention,
(a) is a cross-sectional view showing a state in which a conductive bump group is formed on a supporting substrate surface, (b) is a cross-sectional view showing a state in which conductive bumps are adhered and formed on a supporting substrate surface, (c) is FIG. 4 is a cross-sectional view showing a state in which synthetic resin sheet layers in which tips of conductive bumps on the surface of a supporting base material are laminated and arranged are integrated.

FIG. 2 schematically shows another embodiment of the present invention, in which (a) shows a state in which a synthetic resin sheet and a copper foil are laminated and arranged on the surface of a supporting substrate on which conductive bumps are formed. A sectional view showing the state, (b) is a sectional view showing a state in which the tip of the conductive bump penetrates the synthetic resin sheet layer and is electrically connected and integrated with the copper foil, and (c) shows a state in which both surfaces are patterned. Sectional drawing to show.

FIG. 3 schematically shows still another embodiment of the present invention, in which (a) is a copper foil having conductive bumps formed on both sides of a double-sided printed wiring board via synthetic resin sheets. FIG. 3B is a cross-sectional view showing a state of stacking and arranging, and FIG. 6B is a cross-sectional view showing a state where the tip end portion of the conductive bump penetrates the synthetic resin sheet layer and is electrically connected and integrated with the copper foil.

[Explanation of symbols]

1 …… Cylinder with heating device 1a …… Silin part
1b …… Through hole (extrusion port) 2 …… Support base
3, 3 '... Supporting substrate (copper foil, etc.) 3a, 3a' ...
… Wiring pattern 4… Melted conductive material
5 ... Conductive bump 5 '... Wiring connection part 6
…… Synthetic resin sheet 7 …… Double-sided wiring board
8: Double-sided copper-clad laminate for multilayer printed wiring boards

Claims (3)

[Claims] 1. A step of forming a projecting conductive bump group by extruding or dropping a melted conductive material on a predetermined area surface of a sheet-shaped or plate-shaped support base material and then solidifying the conductive material, A step of stacking a synthetic resin sheet on the surface on which the projecting conductive bump group is formed to form a laminated body, and pressing the laminated body to attach the tip of the projecting conductive bump group to the synthetic resin sheet. And a step of penetrating in the thickness direction. 2. A step of forming a projecting conductive bump group by extruding or dropping a melted conductive material on a predetermined region surface of a sheet-shaped or plate-shaped supporting base material and then solidifying the conductive material, A step of sequentially stacking a synthetic resin sheet and a conductive metal layer on the surface on which the protruding conductive bump group is formed to form a laminated body, and pressing the laminated body to provide a tip portion of the protruding conductive bump group. A step of penetrating in the thickness direction of the synthetic resin sheet and connecting the sheet to the conductive metal layer. 3. A step of forming a projecting conductive bump group by extruding or dropping a melted conductive material on a predetermined area surface of a sheet-shaped or plate-shaped support base material and then solidifying the conductive material, A step of sequentially stacking a synthetic resin sheet and a conductive metal layer on the surface on which the protruding conductive bump group is formed to form a laminated body, and pressing the laminated body to provide a tip portion of the protruding conductive bump group. A method of manufacturing a printed wiring board, comprising: a step of penetrating in the thickness direction of the synthetic resin sheet and connecting to the conductive metal layer; and a step of patterning the wiring of the conductive metal layer. .