JP2002280694A - Printed wiring board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a defective connection in a pad part, decrease manufacturing cost, and thin a printed wiring board. SOLUTION: An internal layer circuit 3 and a so-called dummy land 4 which does not constitute a circuit with the internal layer circuit 3 are formed on a base 2. A first insulating resin layer 5 not containing glass fibers is laminated on the base 2, and a resin sheet 6 not having a plating catalyst action is formed on the first insulating resin layer 5. Boring is performed with carbon gas laser beams, and a non-through connection hole 10 is formed by a electroless copper plating process. A pad 15 is formed in the non-penetration connection hole 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having pads for electrically connecting electronic components by bonding, and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIGS. 6 and 7 are cross-sectional views for explaining a conventional method of manufacturing a printed wiring board. FIG. 6 (a)
In the figure, 21 is a substrate, on which an inner layer circuit 22 is formed, and on this inner layer circuit 22, a first insulating resin layer 23 containing no glass fiber is formed on the substrate 21 by lamination. Land portions 24 are formed on the first insulating resin layer 23.

As shown in FIG. 1B, a second insulating resin layer 25 is formed on the first insulating resin layer 23, and is formed in a ring shape on the second insulating resin layer 25. Terminal portion 26 is provided. By irradiating the second insulating resin layer 25 with the carbon dioxide laser beam 27 from above the terminal portion 26, a non-through hole 28 reaching the land portion 24 is formed as shown in FIG.

[0004] As shown in FIG. 7 (a), the terminal portion 26 is used as an electrode, and the terminal portion 2 is formed by electrolytic copper plating.
By depositing copper on the surface 6 and promoting the growth in the hole by using an additive, the non-through hole 28 is also filled with copper to form the pad portion 30 and the printed wiring board 31. As shown in FIG. 2B, the wire portion 16 is fixed to the pad portion 30 by a wire bonding process using an ultrasonic thermocompression bonding method, so that the pad portion 30 and the wire lead 16 are electrically connected.

[0005]

In the above-described wire bonding process for the conventional printed wiring board 31, the wire leads 16 are electrically connected to the pad portions 30 while applying ultrasonic waves and pressure on the heated plate. ing.
In this case, only the first insulating resin layer 23 that does not include glass fiber that is weak in strength is provided below the pad portion 30, so that the first insulating resin layer 23 is relatively If the layer is thin, it may be deformed, and the pad portion 30 may be depressed, and the wire lead 16 and the pad portion 3
There is a problem that a connection failure occurs between 0 and 0. Further, in the above-described conventional method for manufacturing a printed wiring board, since it is necessary to provide the terminal portion 26 as an electrode for electrolytic plating, the number of manufacturing steps is increased, so that the manufacturing cost is increased. Further, since the plating film is also formed on the terminal portions 26, the protruding height t of the pad portions 30 protruding from the surface of the second insulating resin layer 25 increases, and the printed wiring board 31
There was also a problem that it was not possible to reduce the thickness.

The present invention has been made in view of the above-mentioned conventional problems, and a first object is to prevent a connection failure in a pad portion. A second object is to reduce manufacturing costs. A third object is to reduce the thickness of the printed wiring board.

[0007]

In order to achieve this object, the invention according to claim 1 is directed to a first embodiment formed on an inner layer circuit.
A printed wiring board comprising: an insulating layer; a second insulating layer laminated on the first insulating layer; and a bonding pad formed on the second insulating layer. The insulating layer is a resin layer containing no glass fiber, and the first insulating layer is provided with an interlayer connection hole that does not constitute a circuit in which metal is filled in the hole, corresponding to the pad portion. Therefore, the metal in the interlayer connection hole functions as a reinforcing base for the pad portion.

The invention according to claim 2 includes a step of forming an inner layer circuit and a land portion which does not constitute a circuit on the base material, a step of forming an insulating resin layer containing no glass fiber on the base material, Forming a non-catalytic layer having no plating catalytic action on the surface of the insulating resin layer, forming a through hole reaching the land in the non-catalytic layer and the insulating resin layer by laser, Filling a conductive member in the through hole by plating. Therefore, when the electroless plating process is performed, plating is deposited on the inner layer circuit in the through hole without plating being deposited on the non-catalytic layer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view for explaining a method for manufacturing a printed wiring board according to the present invention in a pre-process, FIG. 2 is a cross-sectional view for explaining a manufacturing method in a middle process, and FIG. FIG. 3 is a cross-sectional view for explaining the method.

In FIG. 1A, reference numeral 2 denotes a substrate,
On the base material 2, an inner layer circuit 3 and a land portion not connected to the inner layer circuit 3, that is, a so-called dummy land portion 4 are formed. Here, the dummy land portion means an independent land portion on a circuit board which does not constitute a circuit. A first insulating resin layer 5 containing no glass fiber is formed on the substrate 2 on the inner layer circuit 3 and on the dummy land portions 4, and a plating catalytic action is formed on the first insulating resin layer 5. A resin sheet 6 is formed as a non-catalytic layer having no surface. By irradiating the carbon dioxide laser beam 7 from above the resin sheet 6, a non-through hole 8 reaching the land 4 is formed in the resin sheet 6 and the first insulating resin layer 5 as shown in FIG. I do.

As shown in FIG. 1C, when the electroless copper plating is performed, copper is deposited on the land 4 formed of a metal having a catalytic action. The grown copper grows in the non-through hole 8,
The non-through hole 8 is filled with copper to form a non-through connection hole 10 as an interlayer connection hole. At this time, since the resin sheet 6 having no plating catalytic action is provided on the surface of the first insulating resin layer 5, no copper is deposited on the resin sheet 6.

In FIG. 2A, a second insulating resin layer 11 is formed on a resin sheet 6 and the second insulating resin layer 1 is formed.
A resin sheet 12 having no plating catalytic action is formed on 1. Carbon dioxide laser light 13 from above resin sheet 12
As shown in FIG. 2B, the non-penetrating connection holes 10 are formed in the resin sheet 12 and the second insulating resin layer 11 as shown in FIG.
Is formed in the inverted trapezoidal non-through hole 14.

As shown in FIG. 3A, when the electroless copper plating treatment is performed, copper deposits on the non-through connection hole 10 formed of copper having a catalytic action. Copper deposited on 10 grows in non-through holes 14. Accordingly, the non-through hole 14 is filled with copper to form a pad portion 15 having a reverse trapezoidal cross section, and the printed wiring board 1 is formed. At this time, since the resin sheet 12 having no plating catalytic action is provided on the surface of the second insulating resin layer 11, no copper is deposited on the resin sheet 12.

As shown in FIG. 1B, a wire lead 16 is fixed on the pad portion 15 by a wire bonding process using an ultrasonic thermocompression bonding method, so that the pad portion 15 and the wire lead 16 are electrically connected. I do. At this time, the non-penetrating connection hole 10 filled with copper is in contact with the lower end of the pad part 15, and the non-penetrating connection hole 10 is erected on the land part 4. Is added, the non-through connection hole 13 functions as a reinforcing base,
It is possible to prevent the pad section 15 from being depressed or deformed. Therefore, poor electrical connection between the pad portion 15 and the wire lead 16 can be prevented.

In order to form the pad portion 15, the second
A resin sheet 12 having no plating catalyst action is formed on the surface of the insulating resin layer 11 of FIG.
By depositing copper on the non-penetrating connection hole 10, it is not necessary to form the terminal 26 for the electrode required for the electrolytic plating process as in the related art. Therefore, since a part of the manufacturing process can be omitted, not only the manufacturing time can be shortened, but also the manufacturing cost can be reduced.

Since the cross-section of the pad portion 15 is formed in an inverted trapezoidal shape, the area of the surface to which the wire lead 16 is bonded is increased, and the displacement of the wire lead 16 with respect to the pad portion 15 can be prevented. 1
Insufficient electrical connection between the wire leads 5 and the wire leads 16 can be prevented. Further, since no copper is deposited on the resin sheets 6 and 12, the height of the non-through connection hole 10 and the height of the pad portion 15 do not increase, so that the printed wiring board 1 can be made thinner.

FIGS. 4 and 5 show a second embodiment of the present invention. FIG. 4 is a cross-sectional view for explaining a manufacturing method in a pre-process, and FIG. 5 is a sectional view for explaining a manufacturing method in a post-process. It is sectional drawing. The second embodiment is different from the above-described first embodiment in that a prepreg 17 is used as a non-catalyst layer, and a second insulating resin layer 18 is laminated via the prepreg 17 by a lamination press method. In that the first insulating resin layer 5 is laminated.

That is, as shown in FIG.
A prepreg 17 having no plating catalytic action is formed on the insulating resin layer 5 of FIG. 1, and the carbon dioxide laser beam 7 does not penetrate the prepreg 17 and the first insulating resin layer 5 as shown in FIG. A hole 8 is formed. As shown in FIG. 3C, when the electroless copper plating process is performed, the non-through holes 8 are filled with copper to form the non-through connection holes 10 and the resin sheet 6 is formed.
No copper is deposited on top.

In FIG. 5A, reference numeral 18 denotes a second insulating resin layer, which is a pad portion 1 having an inverted trapezoidal cross section.
9 is provided so as to penetrate the second insulating resin layer 18. This second insulating resin layer 18 is
The printed wiring board 20 is formed by laminating the first insulating resin layer 5 via the prepreg 17 by a lamination press method so that the printed wiring board 10 is in contact with the non-through connection hole 10. As shown in FIG. 2B, the wire portion 16 is fixed on the pad portion 19 by wire bonding using an ultrasonic thermocompression bonding method, so that the pad portion 19 and the wire lead 16 are electrically connected.

In the second embodiment, the second insulating resin layer 1 is formed using a prepreg 17 which is a non-contact layer.
By forming the layer 8 on the first insulating resin layer 5, the manufacturing process can be further simplified, and the manufacturing cost can be reduced.

The resin sheets 6 and 12 serve as non-catalytic layers.
Although the example of the prepreg 17 has been described, a plating resist or the like may be used. In other words, a layered member that does not have a plating catalytic action and is perforated by a laser beam may be used. In addition, although the non-penetrating connection hole 10 is used as the interlayer connection hole, a through connection hole may be used. In short, it is only necessary that the hole be filled with metal.

[0022]

As described above, according to the first aspect of the present invention, it is possible to prevent poor electrical connection in the pad portion.

According to the second aspect of the present invention, not only the manufacturing time can be shortened, but also the manufacturing cost can be reduced. Further, the thickness of the printed wiring board can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a pre-process of a method for manufacturing a printed wiring board according to the present invention.

FIG. 2 is a cross-sectional view for explaining a middle step of the method for manufacturing a printed wiring board according to the present invention.

FIG. 3 is a cross-sectional view for explaining a post-process of the method for manufacturing a printed wiring board according to the present invention.

FIG. 4 is a cross-sectional view for explaining a pre-process of a manufacturing method according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view for explaining a post-process of the manufacturing method according to the second embodiment of the present invention.

FIG. 6 is a cross-sectional view for describing a pre-process of a conventional method for manufacturing a printed wiring board.

FIG. 7 is a cross-sectional view for explaining a post-process of a conventional method for manufacturing a printed wiring board.

[Explanation of symbols]

1, 20: printed wiring board, 2: base material, 3: inner layer circuit,
Reference numeral 4 denotes a land portion, 5 denotes a first insulating resin layer containing no glass fiber, 6, 12 denotes a resin sheet having no plating catalytic action, 7 denotes a carbon dioxide laser beam, 8 denotes a non-through hole, 10 denotes a non-through hole. Connection holes, 12, 18, second insulating resin layer, 15, 1
9: pad portion, 16: wire lead, 17: prepreg.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenshiro Fukusato 1065 Kusoda, Ninomiya-cho, Haga-gun, Tochigi Prefecture Inside the Haga Plant of Hitachi AIC Co., Ltd. F-term (reference) at the Hitachi AIC Co., Ltd. Haga factory HH24 HH32

Claims (2)

[Claims] A first insulating layer formed on the inner layer circuit;
In a printed wiring board having a second insulating layer laminated on the first insulating layer and a bonding pad formed on the second insulating layer, the first insulating layer may be made of glass fiber. Wherein the first insulating layer is provided with an interlayer connection hole which does not constitute a circuit in which a metal is filled in the hole, corresponding to the pad portion. 2. A step of forming an inner layer circuit and a land portion that does not constitute a circuit on a substrate, a step of forming an insulating resin layer containing no glass fiber on the substrate, and plating the surface of the insulating resin layer. A step of forming a non-catalytic layer having no catalytic action, a step of forming a through hole reaching the land portion in the non-catalytic layer and the insulating resin layer by laser, and a conductive hole in the through hole by electroless plating. Filling a member.