JP2002223069A - Method for manufacturing printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a printed board which can securely protect a conductor layer when a via hole is filled and prevent the printed board from deforming. SOLUTION: When the via hole 5 is filled with a plating conductor 7, a reinforcing plate 10 is put covering the entire surface of copper foil 4 across a thermal peeling sheet 11 and a terminal 13 is brought into contact with the copper foil 4 from the side of an insulating substrate 3. Consequently, the surface on the side of the copper foil 4 can completely be sealed with the reinforcing plate 10, so the copper foil 4 is prevented from being contaminated with plating liquid 22. A one-side coppered laminated plate 2 can be reinforced by superposing the reinforcing plate 10 and prevented from deforming during operation. Further, when the terminal 13 is pressed into contact with the copper foil 4, the tip of the terminal 13 can be prevented from breaking through the copper foil 4. Consequently, it is made easy to handle the printed board 1 in a plating process and the operability can be improved.

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 circuit board.

[0002]

2. Description of the Related Art As a basic technique for manufacturing a multilayer circuit board, a method of filling a via hole formed through an insulating layer of a printed board with a conductive material and electrically connecting circuits on both sides of the printed board is known. Are known. At this time, as a method of filling the via hole with a conductive material, for example, an electroplating method can be used. This is, for example, FIG.
As shown in FIG. 1, the single-sided copper-clad laminate 101 having the via hole 102 formed therein is immersed in a plating solution 103, and a plating metal 105 is deposited in the via hole 102 by using the copper foil 104 as one electrode. 102
Is to be filled.

By the way, when performing the electroplating as described above, it is necessary to prevent the plating solution 103 from adhering to the copper foil 104. For this reason, for example, a PET (polyethylene terephthalate) film 106 is attached to the entire surface of the copper foil 104 to protect it.

[0004]

However, in order to use the copper foil 104 as one electrode in electroplating, a conductor 108 for connection to a power source 107 must be connected to the copper foil 10.
4 must be connected. Therefore, the conductor 108 is bonded to the surface of the copper foil 104 by soldering, and extends outside from the gap between the PET film 106 and the copper foil 104. However, in such a method, there is a possibility that the plating solution 103 may intrude from the gap between the copper foil 104 and the PET film 106 in the extending portion 109 of the conductive wire 108 and adhere to the copper foil 104.

In recent years, with the demand for smaller and lighter electronic devices, printed circuit boards have been made thinner.
The printed circuit board may be deformed during the plating step, and handling is difficult.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a printed circuit board capable of reliably protecting a conductor layer when filling a via hole and preventing deformation during a plating process. It is to provide a manufacturing method.

[0007]

According to a first aspect of the present invention, there is provided a method for manufacturing a printed circuit board.
A plated conductor is formed by electroplating using a conductor layer as one electrode in a via hole reaching the conductor layer through the insulation layer of a printed circuit board having a conductor layer formed on one of the front and back surfaces of the insulation layer. A method of manufacturing a printed board to be filled, wherein another board is overlapped with an adhesive member so as to cover the entire surface of the conductor layer, and a conductive terminal is penetrated from the surface on the insulating layer side to the insulating layer. And contact the conductor layer.

Here, the material of the other substrate is not particularly limited as long as it is an insulating substrate. For example, a glass cloth base epoxy resin substrate or the like usually used as an insulating substrate of a printed circuit board can be preferably used. Alternatively, another printed circuit board may be used as another board, and the printed circuit boards may be overlapped with the conductor layers facing inward.

As the adhesive member, for example, a member having an adhesive layer formed on both surfaces of a substrate can be used. The material of the base material used for the adhesive member is not particularly limited, and for example, a fibrous product such as paper, cloth or nonwoven fabric, a polymer such as plastic or rubber, or a laminate thereof can be used. The shape of the substrate is not particularly limited as long as a printed substrate and another substrate can be overlapped on both surfaces, and for example, a substrate formed in a plate shape, a sheet shape, or a net shape can be used.

The adhesive used for the adhesive layer of the adhesive member is not particularly limited, and examples thereof include a rubber adhesive, an acrylic adhesive, a styrene / conjugated diene block copolymer adhesive, and a silicone adhesive. Can be used. The adhesive may be blended with an appropriate additive such as a crosslinking agent, a tackifier, a plasticizer, a filler, an antioxidant, and the like, if necessary.

According to a second aspect of the present invention, there is provided the method of manufacturing a printed circuit board according to the first aspect, wherein the step of forming a via hole in the insulating layer includes the step of forming the via hole in the insulating layer in the same manner as the formation of the via hole. It is characterized in that a terminal through hole for penetrating the terminal is formed.

Here, the method of forming the via hole and the terminal through-hole is not particularly limited, and for example, a laser, a drill or the like can be used.

According to a third aspect of the present invention, there is provided the method for manufacturing a printed circuit board according to the first or second aspect, wherein the adhesive member is heated to a temperature higher than the temperature at the time of electroplating to improve the adhesiveness. Characterized by losing.

Here, in order to lose the adhesiveness by heating to a temperature higher than the temperature at the time of electroplating, for example, the bonding member is mixed with a foaming agent which foams at a temperature higher than the temperature at the time of electroplating. Agents can be used.
In such a case, examples of the foaming agent include decomposition type inorganic foaming agents such as ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, and azides; and trichloromonofluoromethane and dichloromonofluoromethane. Fluorinated alkanes, azo compounds such as azobisisobutyronitrile, azodicarbonamide, barium azodicarboxylate, paratoluenesulfonyl hydrazide and diphenylsulfon-3,3′-disulfonyl hydrazide;
Hydrazine compounds such as 4,4'-oxybis (benzenesulfonylhydrazide) and allylbis (sulfonylhydrazide); semicarbazide compounds such as ρ-toluylenesulfonyl semicarbazide and 4,4'-oxybis (benzenesulfonyl semicarbazide); Triazole compounds such as morpholyl-1,2,3,4-thiatriazole, N-nitroso such as N, N'-dinitrosopentamethylenetetramine and N, N'-dimethyl-N, N'-dinitrosoterephthalamide An organic foaming agent such as a compound can be used.

[0015]

According to the first aspect of the present invention, when filling a via hole with a plated conductor, another substrate is overlapped via an adhesive member so as to cover the entire surface of the conductor layer. Then, a conductive terminal is passed through the insulating layer from the surface on the side of the insulating layer to make contact with the conductor layer. Thus, since the terminal is brought into contact with the conductor layer from the insulating layer side, the surface on the conductor layer side can be completely sealed with another substrate. This can prevent the conductive layer from being contaminated by the plating solution.

Further, the printed board can be reinforced by overlapping another board. Therefore, it is possible to prevent the printed circuit board from being deformed during the plating process, and to prevent the tip of the terminal from breaking through the conductor layer.
Thereby, the handling of the printed circuit board during the plating process can be facilitated, and the workability can be improved.

According to the second aspect of the present invention, in the step of forming a via hole in the insulating layer, the terminal through-hole is formed by the same method as the formation of the via hole. With this configuration, the formation of the via hole and the formation of the terminal through-hole can be performed at the same time, so that the process can be simplified. In addition, by forming the terminal through-hole in advance, the terminal can be easily penetrated through the insulating layer, and the contact between the terminal and the conductor layer can be secured.

According to the third aspect of the present invention, the adhesive member loses adhesiveness when heated to a temperature higher than the temperature at the time of electroplating. Thereby, at the time of electroplating, the adhesiveness of the adhesive member is maintained. On the other hand, when it is desired to peel the printed board from another board, the adhesive is lost by heating to a higher temperature than during the electroplating, and the peeling can be easily performed.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Next, a first embodiment of the present invention will be described in detail with reference to FIGS.

The starting material of the printed circuit board 1 of this embodiment is a single-sided copper-clad laminate 2. The single-sided copper-clad laminate 2 is formed on one surface (the lower surface side in FIG. 1) of an insulating substrate 3 (corresponding to the insulating layer of the present invention) formed of, for example, a plate-like glass cloth epoxy resin. This is a known structure to which a copper foil 4 (corresponding to the conductor layer of the present invention) is attached (FIG. 1A).

On the surface of the single-sided copper-clad laminate 2 on which the copper foil 4 is formed, a reinforcing plate 10 (corresponding to another substrate of the present invention) is attached to a heat-peelable sheet 11 (corresponding to an adhesive member of the present invention). Are overlapped (FIG. 1B). Reinforcement plate 10
Is made of, for example, a glass cloth epoxy resin in the form of a plate having a thickness of 1000 μm, and is slightly larger than the single-sided copper-clad laminate 2 so that the entire surface of the copper foil 4 can be completely covered. It is possible. In addition, the heat release sheet 11
Has a structure in which, for example, an adhesive layer containing a foaming agent is formed on both surfaces of a polyester film.

In the single-sided copper-clad laminate 2, the surface of the insulating substrate 3 opposite to the copper foil 4 (the upper surface in FIG. 1)
For example, protective film 1 made of polyethylene terephthalate
2 is pasted (FIG. 1C). And the insulating substrate 3
Is irradiated to a predetermined position to form a via hole 5 that penetrates in the thickness direction of the insulating substrate 3 and reaches the copper foil 4. At this time, a terminal through hole 6 for penetrating a terminal 13 to be described later is simultaneously formed near the end of the single-sided copper-clad laminate 2 (FIG. 1D). Laser processing can be performed by, for example, a pulse oscillation type carbon dioxide laser processing apparatus. In this case, the pulse energy is 2.0 mJ or more.
It is desirable to form under conditions of 10.0 mJ, pulse width of 1 μs to 100 μs, pulse interval of 0.5 ms or more, and shot number of 3 to 50. Further, it is preferable that the inner diameter of the terminal through hole 6 be substantially the same as or slightly smaller than the diameter of the terminal 13. This is to prevent the plating solution 22 from entering the hole from the gap between the terminal 13 and the opening edge 6A of the terminal through hole 6.

Thereafter, the protective film 12 is removed, and a desmear process is performed to remove the resin remaining inside the formed via hole 5. The desmear treatment can be performed by, for example, potassium permanganate treatment, oxygen plasma treatment, corona discharge treatment, or the like.

Next, a terminal 13 made of a conductive metal is passed through the terminal through hole 6 so that
3A is brought into contact with the copper foil 4 (FIG. 1E). The terminal 13 is formed in a substantially bar shape with a circular cross section, and one end (the lower end in FIG. 1) is tapered below a position corresponding to the opening edge 6A of the terminal through hole 6. In the terminal 13, a portion exposed from the insulating substrate 3 (above a position corresponding to the opening edge 6A in FIG. 1).
Is covered with an insulating film 14 in order to prevent the plating solution 22 from adhering and to facilitate current management.

Next, a plated conductor 7 is formed by an electroplating method using the copper foil 4 as one electrode. FIG. 3 schematically shows the electroplating apparatus 20. The single-sided copper-clad laminate 2 to which the reinforcing plate 10 is attached is sandwiched between metal clips 24 attached to both ends of a work table 23 of the electroplating apparatus 20. At this time, the one end 24A of the clip 24 presses the end 13B (the left end in FIG. 3) of the terminal 13 on the opposite side to the side inserted into the terminal through hole 6 to securely connect the terminal 13 to the copper foil 4. , And electrical continuity is established between the copper foil 4, the terminal 13, and the clip 24. A conducting wire 26 for connecting to a DC power supply 25 extends from the clip 24.
Further, the reinforcing plate 10 is fixed to the worktable 23 with screws 28.

The worktable 23 to which the single-sided copper-clad laminate 2 is fixed and the plating electrode 27 are immersed in a container 21 filled with a plating solution 22, and the copper foil 4 and the plating electrode 27 are And a DC voltage is applied. Then
A plating metal is deposited on the copper foil 4 exposed at the bottom of the via hole 5 to form a plating conductor 7 (FIG. 2F).

Next, a conductive bump 8 made of a material having a low melting point such as solder is formed by bump plating so as to overlap the plated conductor 7 in the via hole 5. The conductive bumps 8 are filled so as to slightly protrude from the upper surface of the insulating substrate 3 (FIG. 2G).

Thereafter, the heat release sheet 11 is subjected to a heat treatment to foam the foaming agent contained in the adhesive layer, thereby separating the single-sided copper-clad laminate 2 and the reinforcing plate 10 (FIG. 2).
H).

Finally, the printed circuit board 1 is completed by etching the copper foil 4 to form a predetermined conductor circuit 9.

As described above, according to the present embodiment, when filling the via hole 5 with the plated conductor 7, the reinforcing plate 10 is overlapped with the heat release sheet 11 so as to cover the entire surface of the copper foil 4. Then, the terminal 13 is brought into contact with the copper foil 4 from the insulating substrate 3 side. Thereby, the surface on the copper foil 4 side can be completely sealed by the reinforcing plate 10, so that the copper foil 4
Can be prevented from being contaminated by the plating solution 22. Moreover, the single-sided copper-clad laminate 2 can be reinforced by stacking the reinforcing plates 10, and the single-sided copper-clad laminate 2 can be prevented from being deformed during operation. Further, when the terminal 13 is pressed and brought into contact with the copper foil 4, the tip of the terminal 13 can be prevented from breaking through the copper foil 4. This makes it easier to handle the printed circuit board 1 during the plating process,
Workability can be improved.

Further, by simultaneously forming the terminal through holes 6 when forming the via holes 5, the process can be simplified. In addition, by forming the terminal through holes 6 in advance, the terminals 13 can be easily penetrated through the insulating substrate 3 and the contact between the terminals 13 and the copper foil 4 can be secured.

Further, the adhesive layer of the heat release sheet 11
It contains a foaming agent that foams when heated to a higher temperature than during electroplating. Thereby, while the adhesiveness is maintained during the electroplating, when the single-sided copper-clad laminate 2 and the reinforcing plate 10 are separated, the separation is easily performed by heating to a higher temperature than during the electroplating. be able to.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the single-sided copper-clad laminate 2 having the via holes 5 formed therein and the other single-sided copper-clad laminate 32
(Corresponding to another substrate of the present invention) and copper foil 4,
The heat release sheets 11 are sandwiched with the 34 side facing inward. Thereby, the two single-sided copper-clad laminates 2 and 32 reinforce each other, and can prevent deformation. At this time, in order to completely seal the copper foils 4 and 34 with each other, it is preferable that the two single-sided copper-clad laminates 2 and 32 have the same size.

Then, the terminals 13 are passed through the insulating substrates 3 and 33 of the single-sided copper-clad laminates 2 and 32 to form copper foils 4 and 34.
Contact. In the present embodiment, the terminal through-hole is not formed in advance, but the terminal 13 can be easily penetrated through the insulating substrate 3 by sharpening the tip of the terminal 13. In addition, since the insulating substrate 3 is in close contact with the terminals 13, there is no possibility that the plating solution will enter the holes.

The single-sided copper-clad laminates 2 and 32 are immersed in a vessel 21 filled with a plating solution 22 as in the first embodiment, and plated conductors 7 and 37 are formed by electroplating. Next, the plated conductors 7, 3 in the via holes 5, 35
7, conductive bumps 8 and 38 are formed by bump plating.

Thereafter, the heat release sheet 11 is subjected to a heat treatment so that the foaming agent contained in the adhesive layer is foamed.
The single-sided copper-clad laminates 2 and 32 are peeled off. Finally, the printed circuit board is completed by etching the copper foils 4 and 34 to form predetermined conductor circuits.

As described above, also in the present embodiment, the first
The same operation and effect as the embodiment can be obtained.

It should be noted that the technical scope of the present invention is not limited by the above-described embodiment, and, for example, those described below are also included in the technical scope of the present invention.
In addition, the technical scope of the present invention extends to an equivalent range. (1) In the first embodiment, the tip of the terminal 13 is tapered, but according to the present invention, the shape of the terminal is not limited to this embodiment, and may be, for example, a rod. (2) In the second embodiment, the tip of the terminal 13 is tapered, but according to the present invention, the shape of the terminal is not limited to this embodiment, and may be, for example, a screw shape.

(3) According to each of the above embodiments, the heat release sheet 11 is used as the adhesive. However, according to the present invention, the material of the adhesive is not limited to the above embodiments.
Any material can be used as long as it retains adhesiveness during electroplating and can be peeled off thereafter. (4) According to the first embodiment, the terminal through-hole 6 is formed in the insulating substrate 3 in advance, and the terminal 1 is inserted into the terminal through-hole.
3, but it is not always necessary to form the terminal through-hole according to the present invention. In the second embodiment, the terminal through-hole is not formed, but the terminal through-hole may be formed in advance. (5) According to the first embodiment, the reinforcing plate 10 is slightly larger than the single-sided copper-clad laminate 2, but according to the present invention, the reinforcing plate has the same size as the single-sided copper-clad laminate. In short, any size may be used as long as the copper foil can be completely covered.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a printed circuit board according to a first embodiment-1 (A) A cross-sectional view of a single-sided copper-clad laminate (B) A reinforcing plate is attached to the copper foil side of a single-sided copper-clad laminate Sectional view (C) Sectional view of a single-sided copper-clad laminate with a protective film attached to an insulating substrate. (D) Sectional view of via-holes and terminal through-holes formed in a single-sided copper-clad laminate. Cross section through terminal

FIG. 2 is a cross-sectional view showing a printed circuit board manufacturing process according to the first embodiment; FIG. 2 (F) is a cross-sectional view in which a plated conductor is formed in a via hole; and (G) is a cross-sectional view in which a conductive bump is formed on the plated conductor. H) Cross-sectional view of peeling of reinforcing plate from single-sided copper-clad laminate (I) Cross-sectional view of printed circuit board of first embodiment

FIG. 3 is a cross-sectional view of the electroplating apparatus according to the first embodiment.

FIG. 4 is a cross-sectional view of another single-sided copper-clad laminate adhered to the single-sided copper-clad laminate of the second embodiment.

FIG. 5 is a sectional view showing a conventional electroplating method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Printed board 3, 33 ... Insulated board (insulating layer) 4, 34 ... Copper foil (conductor layer) 5, 35 ... Via hole 6 ... Terminal through hole 7, 37 ... Plated conductor 10 ... Reinforcement board (other board) 11: Thermal release sheet (adhesive member) 13: Terminal 32: Other single-sided copper-clad laminate (other substrate)

Claims (3)

[Claims] 1. An electric device using a conductor layer as one electrode in a via hole reaching the conductor layer through the insulation layer of a printed circuit board having a conductor layer formed on one of the front and back surfaces of the insulation layer. A method of manufacturing a printed circuit board in which a plated conductor is filled by plating, wherein another substrate is overlapped with an adhesive member so as to cover the entire surface of the conductor layer, and a conductive film is formed from the surface on the insulating layer side to the insulating layer. A method for manufacturing a printed circuit board, comprising: contacting the conductive layer by penetrating a conductive terminal. 2. The method according to claim 1, wherein, in the step of forming a via hole in the insulating layer, a terminal through hole for penetrating the terminal is formed in the insulating layer in the same manner as the formation of the via hole. 3. The method for manufacturing a printed circuit board according to claim 1. 3. The method for manufacturing a printed circuit board according to claim 1, wherein the adhesive member loses adhesiveness when heated to a temperature higher than a temperature at the time of electroplating.