JP2010245193A - Manufacturing method of wiring board, and manufacturing method of multilayer printed board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a cost-effective wiring board allowing for forming a conductive paste through hole with high positional accuracy, and to provide a manufacturing method of a multilayer printed board using the wiring board. <P>SOLUTION: The conductive paste through hole is formed by providing a conductive layer 13 with circuit formation on an insulated substrate 12, laminating a removable film 14 on the conductive layer 13, making a through hole 15 on the removable film 14, the conductive layer 13, and the insulated substrate 12, then filling the through hole 15 with conductive paste 16, and removing the removable film 14. The wiring board 17 thus obtained can be used to manufacture a single-layer or multilayer printed board. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a wiring board and a method of manufacturing a multilayer printed board using the same, and more particularly to a method of forming a conductive paste through hole (paste via) penetrating an insulating base material for interlayer conduction.

  In recent years, as electronic devices have become lighter and thinner, semiconductor chips and components have been downsized, and terminal pitches have been narrowed, the density of wiring and the number of layers have been increasing in single-layer or multilayer printed wiring boards. Features required for the multilayer printed circuit board are thinness and high electrical connection reliability between layers.

  As a method for achieving interlayer conduction in a double-sided wiring board or a multilayer printed board, an interlayer conduction method using plating is known. As specific examples, TH (through hole) plating in which a through hole is made in a substrate with a drill or the like and LVH (laser via hole) in which a hole is made in the surface layer with a laser and plated in the place is known. Yes. However, these plating methods are disadvantageous in terms of cost because the process is complicated and the number of steps is large. Further, since the conductor thickness is increased by plating, the total thickness of the wiring board is increased. In addition, in the circuit, there is a circuit step between the portion where the conductor thickness is increased by plating near the hole and the other portion, which is inconvenient when, for example, a coverlay or a multilayer wiring board is laminated. Furthermore, since it is impossible in principle to arrange a wiring circuit in the TH peripheral portion or LVH peripheral portion, it is disadvantageous for increasing the wiring density.

In recent years, a multilayer printed board using a conductive paste has been proposed as an interlayer connection method instead of plating.
For example, Patent Document 1 describes a wiring board base material in which a masking metal foil is detachably attached to at least one surface of an insulating base material, and a method for manufacturing a multilayer wiring board base material using the same. Has been.
Further, Patent Document 2 has a conductor layer on both surfaces of an insulating base material, and through holes that communicate with each other at the same position with respect to one conductor layer and the insulating base material are provided. A printed wiring board base material in which a peelable masking layer is provided on the surface of the conductor layer, and an opening having a size surrounding the through hole is formed in the masking layer, and a method for manufacturing the same are described.

JP 2004-152882 A JP 2007-234664 A

  In the method for manufacturing a wiring board substrate described in Embodiment 1 of Patent Document 1, a circuit pattern is formed on a single-sided CCL by a chemical etching method, a blind via is formed by laser light irradiation, and a conductive property is formed therein. The paste is filled. Since this manufacturing method requires a copper foil for masking on one side for laser light irradiation, both copper foils cannot be used for circuit formation even if a double-sided CCL is used as a material. Therefore, in order to obtain a double-sided wiring board, it is necessary to align the two single-sided wiring boards so that the circuit side faces outward, and then heat and press to electrically connect the conductive pastes. However, in that case, two laser processing steps are required, which is disadvantageous in terms of cost, and two insulating layers are interposed between the circuits on both sides, so that it is difficult to reduce the thickness of the wiring board.

  In the method for manufacturing a wiring board substrate described in Embodiment 2 of Patent Document 1, a copper foil for masking is heated and pressed on both sides of a glass epoxy prepreg so as to be peelable, and a conformal mask is formed by photolithography. Then, a through hole is formed by laser processing, a conductive paste is filled, a masking copper foil is peeled off, a circuit copper foil is bonded, and a circuit is formed by photolithography. This manufacturing method is disadvantageous in terms of cost because it requires a step of bonding a copper foil (masking copper foil and circuit copper foil) twice on both sides and a photolithography step.

  In the method of manufacturing a printed wiring board substrate described in Embodiment 1 of Patent Document 2, a masking layer is provided on one side of a circuit-formed double-sided CCL, and an opening is formed in the masking layer and the copper foil on one side by the first laser processing. After the formation, an opening having a diameter larger than the opening of the copper foil and a hole in the insulating base are formed in the masking layer by the second laser processing, and the conductive paste is filled. This manufacturing method is disadvantageous in cost because it requires two times of laser processing. Moreover, since the opening diameter of a masking layer and the opening diameter of copper foil and an insulating base material are near, there exists a problem that the energy of the laser processing to copper foil is high, and a masking layer may peel off.

  In the method for manufacturing a printed wiring board substrate described in Embodiment 2 of Patent Document 2, an opening is simultaneously formed in a copper foil on one side when a circuit is formed on both sides CCL, a masking layer is provided, and then laser processing is performed. An opening having a diameter larger than the opening of the copper foil and a hole in the insulating base are formed in the masking layer, and the conductive paste is filled. This manufacturing method has a problem that the laser processing position may be shifted from the position of the copper foil opening because the masking layer covers the opening of the copper foil during laser processing.

  The present invention has been made in view of the above circumstances, and is capable of forming a conductive paste through hole with high positional accuracy, and is advantageous in terms of cost, and a manufacturing method of a multilayer printed circuit board using the same. It is an object to provide a method.

In order to solve the above problems, the present invention comprises a step of providing a conductor layer on one or both sides of an insulating substrate, a step of forming a circuit on the conductor layer, and a film peelable from the conductor layer. After opening a through hole in the peelable film and the conductor layer and the insulating base material, the through hole is filled with a conductive paste, and the peelable film is further peeled off to form a conductive paste. And a method of manufacturing a wiring board, comprising: a step of forming a through hole.
It is preferable that the wiring board is a double-sided wiring board, and the conductive paste through hole conducts a circuit formed on both sides of the insulating base material between layers.
After the circuit and the conductive paste through hole are formed, a cover lay is further laminated on the circuit, heated and pressurized, and simultaneously with the curing of the cover lay, the conductive paste and the It is preferable to have a step of obtaining conduction with the circuit.
As the peelable film, it is preferable to use any of a slightly adhesive film, a UV curable adhesive film, a re-peelable heat-foamed film, or a cooling peelable adhesive film.

Further, the present invention is a method for manufacturing a multilayer printed board configured by laminating a plurality of wiring boards, wherein at least one of the wiring boards is manufactured by the method for manufacturing a wiring board according to the present invention. A method for manufacturing a multilayer printed circuit board is provided.
The present invention is also a method for manufacturing a multilayer printed circuit board configured by laminating a double-sided wiring board with a plurality of other wiring boards, after the double-sided wiring board is manufactured by the wiring board manufacturing method of the present invention. And providing a method for manufacturing a multilayer printed circuit board comprising a step of collectively laminating the obtained double-sided wiring board and the plurality of other wiring boards.

According to the present invention, the formation of the through-hole is only one step, and also when manufacturing a double-sided wiring board, both-sided conductors can be used in the circuit, which is advantageous in terms of cost.
In addition, since the peelable film and conductor used for masking (both sides when manufacturing a double-sided wiring board) and the insulating base can be punched at the same position with the same diameter, the conductive paste through-hole It can be formed with high positional accuracy.

(A)-(g) is sectional process drawing which illustrates typically one Embodiment of the manufacturing method of the double-sided wiring board of this invention. (A)-(g) is sectional process drawing which illustrates typically an example of the manufacturing method of the single-sided wiring board which can be used for the multilayer printed circuit board of this invention. It is sectional drawing which shows typically an example of the manufacturing method of the multilayer printed circuit board of this invention. It is sectional drawing which shows typically an example of the multilayer printed circuit board manufactured by FIG.

The present invention will be described below based on preferred embodiments with reference to the drawings.
1A to 1G show an embodiment of a method for manufacturing a double-sided wiring board according to the present invention. In FIG. 1, 10 is a double-sided CCL, 11 is a conductor layer, 12 is an insulating substrate, 13 is a circuit, 14 is a peelable film, 15 is a through-hole, 16 is a conductive paste through hole made of a conductive paste, Reference numeral 17 denotes a double-sided wiring board obtained by this manufacturing method.

First, as shown in FIG. 1A, a double-sided CCL (CCL: Copper-Clad Laminate, copper-clad laminate) 10 having a copper foil as a conductor layer 11 on each side of an insulating substrate 12 is prepared. Here, an example in which the conductor layer 11 which is a circuit forming material is made of a copper foil is shown. However, in the present invention, the conductor layer 11 is a metal other than copper (for example, nickel) or a form other than the foil (for example, uniform). It may be a thick plating layer). Further, an adhesive (not shown) for bonding the insulating base 12 and the conductor layer 11 may be provided between the insulating base 12 and the conductor layer 11.
As the insulating base 12, various insulators can be used in addition to resin films such as polyimide, polyester, liquid crystal polymer, etc., but a material such as a resin that can easily form a through hole 15 to be described later is desirable.

(Circuit formation process)
Next, as shown in FIG. 1B, circuits 13 are formed on both sides of the insulating base 12 so that necessary portions of the conductor layer 11 become wiring by photolithography or the like. When forming the circuit 13, as a pattern other than the wiring of the circuit 13, for example, an alignment mark used when forming the through hole 15 may be formed from the conductor layer 11. The method for forming the circuit 13 is not limited to the illustrated subtractive method, and an additive method may be employed.

(Conductive paste through hole formation process)
Next, as shown in FIG. 1C, a peelable film 14 is laminated on the circuit 13.
Examples of the peelable film 14 include a slightly adhesive film, a UV curable adhesive film, a re-peelable heat-foamed film, and a cooling peelable adhesive film. The peelable films 14 laminated on the circuits 13 on both sides may be the same or different.

The slightly adhesive film is required to have an adhesive force that can be easily peeled off after the filling of the conductive paste 16 without being peeled off. For example, Soma Tac WA (trade name, manufactured by Somaru) can be mentioned.
The UV curable adhesive film loses its adhesive force when irradiated with UV (ultraviolet rays) and can be easily peeled off. For example, Soma Tac UV (trade name, manufactured by Somaru) can be mentioned.
The re-peelable heat-foamed film has strong adhesion before foaming, and after heating to a predetermined foaming temperature, the foamed layer foams and loses adhesive force, and can be easily peeled off. . For example, Soma Tack TE (trade name, manufactured by Somaru) can be mentioned.
The cooling peelable pressure-sensitive adhesive film has strong adhesion when heated, and when cooled (or returned to room temperature), the adhesive strength disappears and can be easily peeled off. For example, Somatack CR (trade name, manufactured by Somaru) can be mentioned.

Next, as shown in FIG. 1 (d), through-holes 15 are made in the peelable film 14 and the circuit 13 on both sides and the insulating base 12. By forming the through-holes 15 in one step, it is possible to drill holes with the same diameter at the same positions of the peelable film 14 and the circuit 13 and the insulating base 12, so that the peelable film 14 and the circuit 13 can be opened. In addition, it is possible to prevent the positional deviation of the holes of the insulating base 12 and improve the positional accuracy of the conductive paste 16 filling.
An NC (numerical control) driller, a through hole puncher, or the like can be used to form the through hole 15. An apparatus that performs correction according to the dimension (outer shape) of the base material after the circuit 13 is formed for alignment of the through-hole (through-hole) 15 or that is automatically corrected by image recognition by providing an alignment mark. May be used.
After the through hole 15 is formed, smear (dirt) remaining in the through hole 15 is removed (desmear) as necessary. The desmear method is not particularly limited, and examples thereof include plasma desmear treatment. In addition, acid cleaning using hydrochloric acid or sulfuric acid, water cleaning using pure water, or the like can be performed.

Next, as shown in FIG. 1 (e), the through-hole 15 is filled with a conductive paste 16. Examples of the filling method include a screen printing method, a dispensing method, and an ink jet method.
When filling the conductive paste 16, the peelable film 14 functions as a mask when filling the conductive paste 16. That is, the peelable film 14 covers the circuit 13 and the insulating base material 12 at a portion other than the through hole 15, thereby preventing the conductive paste 16 from adhering to the base material surface other than the through hole 15. Can do.

Next, as shown in FIG. 1 (f), the peelable film 14 is peeled from the base material after the circuit 13 is formed, so that the conductive paste 16 is filled in the through holes 15 of the insulating base material 12. Conductive paste through holes are formed, and the double-sided wiring board 17 of this embodiment is obtained.
When the peelable film 14 is peeled, a protrusion (portion protruding from the circuit 13) of the conductive paste 16 is formed according to the thickness of the peelable film 14.
The protrusions are crushed by the pressing force applied to the double-sided wiring board 17 when laminated with a coverlay (see FIG. 1G) or another wiring board (see FIGS. 3 and 4). It adheres to a wide area and can make conduction more reliable.
If the peelable film 14 is too thick, the protrusions of the conductive paste 16 become thick, which may hinder the thinning and surface smoothness of the wiring board. For this reason, it is preferable to use a moderately thin film (for example, about several μm to one hundred μm) as the peelable film 14.

(Coverlay lamination process)
As shown in FIG. 1G, in the double-sided wiring board 17 of this embodiment, the cover lay 1 can be laminated to protect the circuit 13. Examples of the coverlay 1 include a laminate in which an adhesive 3 is provided on one surface of an insulating material 2 made of a resin film such as polyimide.
After laminating the coverlay 1 from both sides of the double-sided wiring board 17, it is heated and pressed by a press machine. At this time, the electrical connection between the circuit 13 by the curing of the coverlay 1 (more specifically, the curing of the adhesive 3) and the curing of the conductive paste 16 is realized at the same time. In this case, the heating process is only once, which is advantageous in terms of cost. Alternatively, a procedure may be employed in which the conductive paste 16 is first heated in an oven or the like to electrically connect the conductive paste 16 and the circuit 13, and then the coverlay 1 is laminated and thermocompression bonded with a press. Is possible.

(Multilayer printed circuit board manufacturing method)
The double-sided wiring board 17 of this embodiment can also be used for manufacturing a multilayer printed circuit board by laminating two or more.
It can also be used to manufacture a multilayer printed board in which a plurality of single-sided wiring boards are stacked on the double-sided wiring board 17. The single-sided wiring board can be manufactured by a process described in, for example, Japanese Patent Application Laid-Open No. 2003-332747.

First, as shown in FIG. 2A, a single-sided CCL 20 having a copper foil 21 on one side of an insulating base material 22 is prepared, and the copper foil 21 of this single-sided CCL is formed into a circuit, as shown in FIG. Thus, the circuit 23 is formed.
Next, as shown in FIG. 2 (c), an interlayer adhesive 24 is laminated on the surface of the insulating base 22 opposite to the copper foil 21, and further, as shown in FIG. 2 (d), the laminated interlayer adhesion is performed. A mask film 25 is laminated on the material 24 as a printing mask.
Next, as shown in FIG. 2E, a hole 26 is formed using a laser or the like. Here, the mask film 25, the interlayer adhesive 24, and the insulating base material 22 are opened by irradiating laser from the mask film 25 surface side. A small hole (not shown) having a diameter smaller than the diameter of the hole 26 may be formed in the circuit 23 so as to release air when filling the paste. Moreover, the desmear process of the hole 26 is performed as needed.
Next, as shown in FIG. 2 (f), the conductive paste 27 is printed from the mask film 25 surface side and filled in the holes 26.
After printing, as shown in FIG. 2G, when the mask film 25 is peeled off, paste protrusions are formed so that the conductive paste 27 filled in the holes 26 protrudes from the surface of the interlayer adhesive 24.
By the above procedure, a single-sided wiring board 28 in which the holes 26 are filled with the conductive paste 27 for interlayer conduction is obtained.

As shown in FIGS. 3 and 4, the multilayer printed circuit board 30 in which a plurality of single-sided wiring boards 28A, 28B, 28C, and 28D are stacked on the double-sided wiring board 17 includes, for example, the double-sided wiring board 17 and the single-sided wiring boards 28A, 28B, It can be manufactured by a method of laminating 28C and 28D at once. The single-sided wiring boards 28A, 28B, 28C, 28D shown in FIG. 3 can be manufactured by the same manufacturing method as the single-sided wiring board 28 shown in FIG.
Each of the single-sided wiring boards 28A, 28B, 28C, and 28D needs to match the position of the conductive paste through hole in a place where interlayer conduction between the wiring boards is required, but in other places, the wiring or conductive paste through The position of the hole can be set arbitrarily.

  As shown in FIG. 3, in the batch stacking, the double-sided wiring board 17 and the single-sided wiring boards 28A, 28B, 28C, and 28D are aligned in a predetermined order, and then heated and pressed by a press. At this time, the electrical connection with the circuits 13 and 23 by the curing of the interlayer adhesive 24 and the curing of the conductive pastes 16 and 27 is realized at the same time. In this case, the heating process is only once, which is advantageous in terms of cost. In addition, after the conductive pastes 16 and 27 are first heated in an oven or the like to electrically connect the conductive pastes 16 and 27 and the circuits 13 and 23, the wiring boards are stacked and thermocompression bonded with a press. It is also possible to adopt.

As mentioned above, although this invention has been demonstrated based on suitable embodiment, this invention is not limited to the above-mentioned example, Various modifications are possible in the range which does not deviate from the summary of this invention.
In the method for manufacturing a wiring board according to the present invention, the circuit can be formed after the conductive paste through hole is formed. In this case, a peelable film is laminated on a substrate with no circuit formed such as CCL, a through hole is made in the peelable film and the conductor and the insulating base material, and the through hole is filled with a conductive paste, After peeling the peelable film, it is possible to adopt a procedure of forming a circuit so that a necessary portion of the conductor layer becomes a wiring by photolithography or the like.

  The method for manufacturing a wiring board of the present invention can also be applied to a single-sided wiring board. In this case, prepare a base material such as single-sided CCL with a conductor layer on one side of the insulating base material, laminate a peelable film to the conductor layer, and penetrate the peelable film and conductor with the insulating base material A through hole is formed, and the through hole is filled with a conductive paste, and a peelable film is peeled off. The circuit can be formed before laminating the peelable film or after filling the conductive paste and peeling the peelable film.

When the method for manufacturing a wiring board according to the present invention is applied to a single-sided wiring board, an adhesive and a second material are provided on the surface of the insulating base opposite to the circuit, similarly to the method for manufacturing a single-sided wiring board shown in FIG. After laminating the peelable film, opening the through hole so that the through hole also penetrates the adhesive and the second peelable film, and filling the through hole with the conductive paste, the second peelable film It is preferable to form a protrusion in which the conductive paste protrudes from the adhesive.
The single-sided wiring board manufactured in this way can also be used as a single-sided wiring board laminated with the double-sided wiring board 17 in the method for manufacturing a multilayer printed board shown in FIG.

  In the method for manufacturing a multilayer printed board of the present invention, the wiring board constituting the multilayer printed board may be a combination of a double-sided wiring board and a single-sided wiring board, all may be a single-sided wiring board, and all may be double-sided wiring. It may be a substrate. When laminating the double-sided wiring boards, an adhesive is laminated between the double-sided wiring boards. This adhesive is preferably laminated in advance on either one of the double-sided wiring boards.

  The present invention can be used for manufacturing various printed wiring boards.

DESCRIPTION OF SYMBOLS 10 ... Double-sided laminated board (CCL), 11 ... Conductor layer (copper foil) before circuit formation, 12 ... Insulating base material, 13 ... Conductor layer (circuit) after circuit formation, 14 ... Peelable film, 15 ... Through Hole (through hole), 16 ... conductive paste (conductive paste through hole), 17 ... wiring board (double-sided wiring board), 28, 28A, 28B, 28C, 28D ... single-sided wiring board, 30 ... multilayer printed board.

Claims (6)

Providing a conductor layer on one or both sides of the insulating substrate;
Forming a circuit in the conductor layer;
Laminating a peelable film with respect to the conductor layer, opening a through hole for the peelable film and the conductor layer and the insulating substrate, and then filling the through hole with a conductive paste, Further, peeling the peelable film to form a conductive paste through hole,
A method of manufacturing a wiring board, comprising:   2. The wiring board according to claim 1, wherein the wiring board is a double-sided wiring board, and the conductive paste through hole conducts a circuit formed on both sides of an insulating base material between layers. Production method.   After the circuit and the conductive paste through hole are formed, a cover lay is further laminated on the circuit, heated and pressurized, and simultaneously with the curing of the cover lay, the conductive paste and the The method for manufacturing a wiring board according to claim 1, further comprising a step of obtaining electrical continuity with a circuit.   The detachable film is any one of a slightly adhesive film, a UV curable adhesive film, a re-peelable heat-foamed film, or a cooling peelable adhesive film. The manufacturing method of the wiring board as described in 2 ..   It is a manufacturing method of the multilayer printed circuit board comprised by laminating | stacking a several wiring board, Comprising: At least one of a wiring board is manufactured with the manufacturing method of the wiring board as described in any one of Claims 1-4. A method of manufacturing a multilayer printed circuit board.   A method for manufacturing a multilayer printed circuit board comprising a double-sided wiring board laminated with a plurality of other wiring boards, wherein the double-sided wiring board is obtained by manufacturing the double-sided wiring board by the wiring board manufacturing method according to claim 2. A method of manufacturing a multilayer printed circuit board, comprising: a step of collectively laminating the double-sided wiring board and the plurality of other wiring boards.

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