JP2001332858A - Multi-layered printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board which take advantage of a build-up method without decreasing electric reliability from a surface mounting land arranged to high density. SOLUTION: In at least part of a surface mounting land 23 of an n-th wiring layer, a subland 25 is formed at a position that the center of the line connecting the center of the surface mounting land and the center of the nearest surface mounting land avoids; a main land 19 is formed at a position corresponding to the surface mounting land below an (n-1)th wiring layer, and a subland is formed at a position corresponding to the subland of the surface mounting land; and the subland 25 of the surface mounting land and the subland 26 of the (n-1)th wiring layer are connected by a via hole 22, and the main land 19 of the (n-1)th wiring layer and the main land 15 of an (n-2)th wiring layer are connected by a via hole 18. Thus, main lands and sublands are connected repeatedly by turns.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board capable of wiring at a high density and having excellent electrical reliability.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and lighter, mounting boards constituting them have been required to have higher density and higher reliability. As a method of reducing the size and increasing the density of a multilayer wiring board, a wiring layer is formed on an insulating substrate on which a wiring layer is formed via an insulating layer, and the wiring layer is further formed on the wiring layer via the insulating layer. A multilayer wiring board is used in which a via hole is formed between wiring layers using a so-called build-up method of forming the wiring board. In this multilayer wiring board, it is easy to form a via hole between the nearest wiring layers, and it is also possible to form a via hole between any wiring layers. There is an advantage that a high-density multilayer wiring board can be obtained as compared with the structure.

FIGS. 9A to 9H show an example of a conventionally known multilayer wiring board by a build-up method.
First, a substrate is prepared in which an insulating resin substrate 101 in which a glass cloth is impregnated with an epoxy resin is bonded with copper foils 102 on both surfaces (FIG. 9A). The copper foil on both sides is etched and patterned (FIG. 9B). Furthermore, on both sides,
An insulating substrate having copper foil 103 adhered to one surface in advance
Heating and pressurizing are performed at a temperature of about 0 ° C. to 200 ° C., and bonding is performed (FIG. 9C).

Next, a portion 104 for forming a via hole is formed.
Is removed by etching (FIG. 9D). At this time, when performing a subsequent hole forming step of the insulating layer by laser processing, a method of removing the copper foil with the same diameter as the hole diameter of the insulating layer is also known, but in this case, the copper foil is masked. Since the laser processing is performed as described above, the insulating layer under the copper foil around the hole may be damaged and peeling may easily occur, so etching is performed larger than the diameter of the hole of the insulating layer to be removed. Is done.

Then, a portion of the insulating layer where a via hole is to be formed is removed by laser processing (FIG. 9E).
Electroless plating and electrolytic plating are performed on both surfaces, and a copper plating layer 105 is formed also in the via hole (FIG. 9F).
The copper layers on both sides, consisting of copper foil and copper plating layers, are etched and patterned using a photoresist (FIG. 9).
(G)). 9 (c) to FIG. 9 if necessary.
By repeating the step (g), a multilayer printed wiring board can be obtained. By the way, as a component mounted on a multilayer printed wiring board, a component typified by a BGA (ball grid array) in which terminals are arranged in a grid and surface mounting is performed on the printed wiring board using solder balls is often used. ing. By arranging the terminals in a grid and performing surface mounting, high-density mounting in which a multi-pin component is mounted in a small area is enabled.

In order to perform such surface mounting, it is necessary to form the surface mounting lands of the components in a grid on the printed wiring board. In order to achieve higher-density mounting, surface mounting lands are required to be formed with a smaller pitch and a larger number of lands. Also, from the viewpoint of mounting, it is desired that the lands for surface mounting be not too small, and therefore, the lands for surface mounting tend to be closer to each other.

[0007]

In a printed wiring board, wiring is performed from a land for mounting components to another land for mounting components. Wiring can be performed only from the same wiring layer as the mounting land. That is, unlike the case having the through through hole, wiring cannot be performed in an arbitrary layer directly from the component mounting land. Moreover,
Since the component mounting lands are arranged in a grid pattern, the area where wiring is possible is small, and the inner surface mounting lands are more restricted by wiring. FIG. 10 shows an example of a ball grid array as an example of an array of lands for surface mounting of components on a printed wiring board. Thus, the lands for surface mounting are arranged on the printed wiring board. Then, as shown in FIG. 10, wiring is performed. However, although wiring can be performed on the outer surface mounting land, it is difficult to perform wiring on the inner surface mounting land. Therefore, it is easy to form a via hole between the nearest wiring layers, and it is also possible to form a via hole between any layers. To take full advantage of a multilayer printed wiring board by a build-up method. Was difficult.

Further, as described above, the surface mounting lands are required to be formed with a smaller pitch and a larger number, that is, to be arranged at a high density. And it is required that the land for surface mounting is not so small. Therefore, in a printed wiring board in which the surface mounting lands of the components are formed in a substantially lattice shape, it is difficult to perform wiring from the surface mounting lands of the components. Since the width is reduced or the distance between the wirings is reduced, the electrical reliability may be reduced.

The present invention has been made in view of the above problems, and does not reduce the electrical reliability even from the surface mounting lands arranged at high density, and makes use of the advantages of the build-up method. It is another object of the present invention to provide a multilayer printed wiring board having high-density wiring.

[0010]

In order to solve the above-mentioned problems, the present invention according to claim 1 of the present invention provides a method for manufacturing a semiconductor device, comprising the steps of: A second wiring layer is formed, and then a third wiring layer is formed on the second wiring layer via an insulating layer, and an n-th wiring layer that is an outer layer from the first wiring layer is formed by a build-up method,
In the multilayer printed wiring board in which the surface mounting lands of the component are formed in a substantially lattice shape on the n-th wiring layer, at least a part of the surface mounting lands of the n-th wiring layer includes the center of the surface mounting land. And a line connecting the closest center of the surface mounting land is formed with a sub-brand such that the center is avoided, and the surface of the (n-1) th wiring layer and the (n-2) th wiring layer is formed. A main land is formed at a position corresponding to the mounting land, and a subland is formed at a position corresponding to the subland of the surface mounting land. The subland between the subland of the surface mounting land and the subland of the (n-1) th wiring layer is formed. Are connected by via holes, and the main land of the (n-1) th wiring layer is connected to the (n-2) th main layer.
The main land and the subland are alternately connected by the via hole such that the main land of the wiring layer is connected by the via hole, and the (n-m-th) wiring layer below the via hole is repeated. ) It is characterized in that it is connected to the wiring at the main land or sub-brand of the wiring layer. Here, n is a natural number of 3 or more, and m is 2 or more n
It represents a natural number less than.

Since the surface mounting lands are formed in a substantially lattice shape, there may be a plurality of surface mounting lands which are closest to a certain surface mounting land. This means that the sub-brand is formed such that the center of the sub-brand avoids the line connecting the centers of all the surface mounting lands. In such a means, if the sub-brand is too close to the nearest surface mounting land, there is a possibility that the reliability such as the electrical insulation may be reduced. Therefore, it was desired that the position of the sub-brand be considered so as not to cause such a fear. The invention according to claim 2 of the present invention has been made in view of such a problem.

According to a second aspect of the present invention, a first aspect is provided.
In the multilayer printed wiring board described in the above, a line connecting the center of the surface mounting land, the center of the closest surface mounting land, a line connecting the center of the surface mounting land, and the center of the subland is formed. The angle is approximately 45 degrees.

[0013]

Embodiments of the present invention will be described below. FIG. 1 shows a partial cross-sectional view of a multilayer printed wiring board according to one embodiment of the present invention. FIG. 1 shows A-
It is a fragmentary sectional view of A '. First, a material was prepared in which a glass cloth was impregnated with an insulating resin such as an epoxy resin or a bismaleimide-triazine resin, and a copper foil was laminated on both surfaces of a resin substrate. A copper foil having a thickness of, for example, about 3 μm to 35 μm is suitably used, but a thinner one is more expensive, and a thicker one is difficult to perform fine patterning, and the weight becomes heavy. It is preferably about 18 μm. Here, the glass epoxy resin substrate 10
(3EC-)
VLP (trade name; manufactured by Mitsui Kinzoku) was used.

Then, a dry film was laminated on both sides, exposed and developed, and the copper foil was etched to form a first wiring layer composed of the main land 11, sub-brand, wiring 12, and the like. Note that the lands and the wiring are electrically connected and are in a continuous state. Here, the expressions "main land" and "sub-brand" are used, but this does not mean that the main land is larger than the sub-land, and it is sufficient if each of the main lands has a size that has no problem in connecting via holes. Of course, the main land may be smaller than the subland. Furthermore, a resin-coated copper foil (APL-4001 (trade name: manufactured by Sumitomo Bakelite)) in which an epoxy resin of 80 μm is bonded to a copper foil of 12 μm.
13 was prepared, and was heated and pressed at a temperature of 170 to 180 ° C. and bonded to both surfaces. Here, the prepared copper foil may be bonded via an adhesive material such as a prepreg. In addition, as the resin substrate with a copper foil, a resin substrate to which a copper foil is bonded or a copper foil to which a resin is applied can be used. As described above, since the method of bonding the resin-attached copper foil or the copper foil is used, the adhesion of the copper layer is stronger than when the copper layer is formed on the insulating layer by electroless copper plating or the like. Does not peel off.

Here, as the copper foil with resin, APL
-B (trade name: manufactured by Sumitomo Bakelite), MCF-600
0 (trade name: manufactured by Hitachi Chemical Co., Ltd.) or the like, and the thickness of the resin is 40 μm to 100 μm, and the thickness of the copper foil is 3 μm to 35 μm.
Is preferably used, but thick ones are difficult to finely pattern and heavy, so that 3 μm
A thickness of 12 μm to 18 μm is more preferable, but a thickness of 12 μm to 18 μm is more preferable because a thin one is expensive and it is difficult to handle only with copper foil. And soft etching of copper foil of thickness 12μm on both sides,
Both sides were made into a 5 μm thick copper foil. Here, by preliminarily thinning the copper foil, it is possible to easily obtain a resin substrate having a thin copper foil on both sides at a low thickness and at a low cost. Thereafter, a dry film was bonded to both surfaces, exposed and developed, and the exposed copper foil was etched to thereby etch the copper foil in the via-hole forming portion and remove it with a diameter of 300 μm.

Next, a laser (carbon dioxide laser, UV
Laser, YAG laser, etc.), a hole is formed by using the first wiring layer as a stopper layer, and the insulating layer in the via hole forming portion is formed into a circular shape having a diameter of 100 μm. Removed so that it is concentric with
A hole was formed. In this case, when forming the first wiring layer,
Leave the copper foil at the end of the board and use it as an alignment mark, remove the copper foil on the via hole formation part at the same time as removing the copper foil on the alignment mark so that the epoxy resin can be transmitted and observed, It is preferable to perform laser processing while performing alignment using the alignment marks for accurate drilling.

Then, in order to remove resin residues in the holes and through holes formed by the laser processing, a cleaning treatment by a permanganate treatment was performed. As a cleaning method, other methods such as plasma processing and abrasive grain spraying are preferable. By performing this process, the copper foil surface corresponding to the side wall surface and the bottom of the hole is cleaned, and the electrical connection by copper plating is reliably performed. In particular, the copper layer surface at the bottom of the hole formed by the laser processing is cleaned, and the electrical connection reliability is improved.

Next, electroless copper plating was performed on the insulating layer to a thickness of 0.2 μm, and electrolytic plating was further performed to a thickness of 10 μm to form a copper plating layer. Here, sputtering may be performed instead of electroless copper plating, and then electrolytic plating may be performed. In such a process, via holes 14 were formed in the portions where the laser holes were formed. Further, the via holes 14 were filled with epoxy resin (BHP-900 (trade name: manufactured by Yamaei)) by screen printing. In addition,
Instead of filling with epoxy resin, filling with plating or conductive paste may be used. As plating,
Although copper electrolytic plating is preferred, other metal plating or electroless plating may be used. Copper paste as conductive paste,
Silver paste and carbon paste can be used. By performing this filling, an insulating layer is not formed on the via hole while air bubbles remain in the via hole,
Bubbles do not rupture at the time of mounting or the like, and disconnection or the like does not occur.

Next, a copper layer having a thickness of 10 μm was formed on both sides using a buff.
m, and at the same time, both ends of the epoxy resin filled in the via holes by screen printing,
Smoothed. Further, the copper layers on both sides were patterned to form a second wiring layer including the main land 15, the sub-brand, the wiring 16, and the like. Hereinafter, the above-mentioned step of bonding the copper foil with resin was repeated to form a third wiring layer and a fourth wiring layer serving as an outer layer. Land 4 for surface mounting on the fourth wiring layer
3. Subland 25 and wiring 24 were formed. Here, it is preferable to fill the via holes with an epoxy resin or the like even after the formation of the fourth wiring layer. It is possible to prevent the solder used for mounting from flowing during mounting to make it difficult to control the amount of solder, and to prevent the solder from blocking the via holes and causing air bubbles inside to burst. Furthermore, solder resist layers (not shown) on both sides
Was formed, and nickel plating and gold plating (not shown) were applied to the surface mounting lands 23 to complete a multilayer printed wiring board.

FIG. 2 is an enlarged view of a surface mounting land portion of the multilayer printed wiring board of this embodiment, and has a diameter of 0.3.
A subland 25 having a diameter of 0.2 mm is formed on a land 23 for surface mounting having a thickness of 0.2 mm. In this embodiment, no sub-brand is formed on the outermost surface mounting land,
The wiring 24 is directly connected to the outer layer. The pitch of the land for surface mounting (distance between centers) was 0.5 mm. In this embodiment, the surface mounting lands and the wiring of the lands are configured as shown in FIGS. FIG. 3 is a perspective view of a portion connected from the fourth wiring layer serving as the outer layer to the second wiring layer via the via, the main land, and the sub-brand. FIG. 4 is an enlarged view of one of the land portions for surface mounting of the fourth wiring layer. A subland 25 is formed on the surface mounting land 23 by being electrically connected thereto. Via holes 22 are formed. A gap is formed around the surface mounting land 23, and a solder resist is formed outside the gap. That is, the solder resist is formed outside the solder resist region 28 shown by the broken line. The gap is not necessarily required, and may be formed so as to cover the circumferential portion of the surface mounting land. However, by forming the sub-brand 25 so as to substantially cover the sub-brand 25, the solder does not flow in the sub-brand direction at the time of component mounting, and there is no mounting defect due to an unstable amount of solder. In the drawing, for the sake of explanation, the space between the surface mounting land 23 and the subband 25 is separated by a solid line, but is actually formed by an integrated copper layer.

As is apparent from FIG. 2, the formation position of the sub-land in the fourth wiring layer is defined by a line connecting the center of one surface mounting land and the center of the closest surface mounting land. The center of the subland is formed so as to avoid the line when it is pulled. By forming in such a position, an electric short circuit hardly occurs between the sub-brand and the nearest surface mounting land. In particular, as in this embodiment, it is preferable to form the sub-brand at a position where the angle between the line, the center of the surface mounting land, and the line connecting the center of the sub-brand becomes 45 degrees. . In the first to third wiring layers as well, lands and sub-brands are formed at positions that overlap the surface mounting lands and sub-brands of the fourth wiring layer when viewed from above. FIG. 3 is a perspective view of a portion connected to the wiring in the second wiring layer from the fourth wiring layer via the land of the third wiring layer as described above. First, a sub-land 25 is formed by being electrically connected to the surface mounting land 23 of the fourth wiring layer, and a via hole 22 is formed between the sub-land 25 of the fourth wiring layer and the sub-land 26 of the third wiring layer. Connected by The sub-land 26 of the third wiring layer is electrically connected to the main land 19 of the third wiring layer, and the main land 19 of the third wiring layer and the main land 15 of the second wiring layer are connected by the via hole 18. ing. The wiring 16 is connected from the main land 15.

When the main land is connected to the wiring in the second wiring layer as in this part, the sub-brand of the second wiring layer connected to the wiring does not necessarily have to be formed. Absent. In this way, by alternately connecting the main land and the subland by the via hole, it is possible to efficiently connect the surface mounting land to the wiring in the inner layer in a small space. In this embodiment, the glass epoxy resin substrate 10 having the first wiring layer formed on both surfaces is used, and the second to fourth wiring layers are formed on both surfaces. However, the first wiring layer is formed on one surface. It is good also as a form which forms the wiring layer after the 2nd wiring layer only on one surface side using the glass epoxy resin substrate made.
The glass epoxy resin substrate 10 may be multilayered and have via holes. In addition, although four wiring layers are provided on one side, it goes without saying that a configuration having four or more wiring layers may be employed.

Note that another embodiment will be disclosed below. The structure of the surface mounting lands and the sub-brand portion of the outer wiring layer (corresponding to the n-th wiring layer) may be the structure shown in FIG. 5 or FIG. The structure shown in FIG. 5 is different from the structure shown in FIG. 4 in that a reinforcing portion 29 is provided so as to reinforce the connection between the land for surface mounting and the subland. And is preferable.
The structure shown in FIG. 6 is different from the structure shown in FIG. 4 in that the surface mounting land and the sub-land are separated from each other, and the connecting portion 30 connects between them. Note that both the reinforcing portion 29 and the connecting portion 30 may be left when etching the copper layer. In the drawing, for the sake of explanation, the space between the surface mounting land 23 and the sub-brand 25 is separated by a solid line, but it is actually formed of an integrated copper layer.
This is the same as in FIG. FIG. 7 shows another embodiment, in which sub-brands 25 are formed on all the surface mounting lands 23 and connected to the inner layer. FIG. 8 shows still another embodiment, in which surface mounting lands 23 are formed in a planar shape, sub-brands 25 are formed, and connected to the inner layer.

[0024]

According to the first aspect of the present invention,
At least a part of the surface mounting land of the n-th wiring layer includes
A subband is formed so that a line connecting the center of the surface mounting land and the center of the closest surface mounting land is avoided, and the (n-1) th wiring layer and the (n-
2) A main land is formed at a position of the wiring layer corresponding to the land for surface mounting, and a subland is formed at a position corresponding to the subland of the land for surface mounting. 1) A via hole connects the sub-landes of the wiring layer, and a via hole connects the main land of the (n-1) th wiring layer and the main land of the (n-2) th wiring layer. The land and the subland are connected alternately by the via hole, and are connected to the wiring by the main land or the subland of the (nm) wiring layer which is the lower wiring layer of the via hole. (Where n is a natural number of 3 or more and m is a natural number of 2 or more and less than n), so that electrical reliability can be improved even from surface mounting lands arranged at high density. Can lower Ku it is possible to perform wiring,
In addition, it is possible to take advantage of the build-up method that it is easy to form a via hole between the nearest wiring layer or an arbitrary wiring layer, and therefore, a multilayer print having high electrical reliability and high density wiring is provided. A wiring board can be obtained.

According to the invention of claim 2 of the present invention, a line connecting the center of the land for surface mounting and the center of the land for surface mounting closest to the land, the center of the land for surface mounting, and 2. The multilayer printed wiring board according to claim 1, wherein an angle formed by a line connecting the center of the substrate and the center is substantially 45 degrees. Therefore, a multilayer printed wiring board having excellent electrical reliability in addition to the effects obtained by the first aspect of the present invention can be obtained.

[0026]

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a multilayer printed wiring board according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a land portion for surface mounting of the multilayer printed wiring board according to the embodiment of FIG. 1;

FIG. 3 is a perspective view of a wiring portion of the multilayer printed wiring board according to the embodiment of FIG. 1;

FIG. 4 is an explanatory view of a land portion for surface mounting of the multilayer printed wiring board of the embodiment of FIG. 1;

FIG. 5 is an explanatory view of a land portion for surface mounting according to another embodiment of the present invention.

FIG. 6 is an explanatory view of a land portion for surface mounting according to still another embodiment of the present invention.

FIG. 7 is an explanatory view of a land portion for surface mounting according to another embodiment of the present invention.

FIG. 8 is an explanatory view of a land portion for surface mounting of a multilayer printed wiring board according to still another embodiment of the present invention.

FIG. 9 is an explanatory diagram of a multilayer printed wiring board by a build-up method.

FIG. 10 is an explanatory diagram of an example of an arrangement of surface mounting lands of a printed wiring board according to the related art.

[Explanation of symbols]

Reference Signs List 10 glass epoxy resin substrate 11, 15, 19 main land 12, 16, 20, 24 wiring 13, 17, 21 copper foil with resin 14, 18, 22 via hole 23 land for surface mounting 25, 26, 27 subland 28 solder Resist region 29 Reinforcing part 30 Connecting part 101 Insulating resin substrate 102, 103 Copper foil 104 Part forming via hole 105 Copper plating layer 106 Surface mounting land 107 Wiring

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Keiichi Matsushita 1-5-1, Taito, Taito-ku, Tokyo Inside Toppan Printing Co., Ltd. (72) Inventor Makoto Okabe 1-1-1, Taito, Taito-ku, Tokyo 5-1-1 Toppan F-term (Reference) in Printing Co., Ltd. HH07 HH26

Claims (2)

[Claims] A second wiring layer formed on at least one surface of the insulating substrate on which the first wiring layer is formed via an insulating layer; and a third wiring layer formed on the second wiring layer via an insulating layer. An nth wiring layer, which is an outer layer from the first wiring layer, is formed by a build-up method in which a wiring layer is formed, and lands for surface mounting of components are formed in a substantially lattice shape on the nth wiring layer. In the multilayer printed wiring board, at least a part of the surface mounting land of the n-th wiring layer includes:
A subband is formed so that a line connecting the center of the surface mounting land and the center of the closest surface mounting land is avoided, and the (n-1) th wiring layer and the (n-
2) A main land is formed at a position of the wiring layer corresponding to the land for surface mounting, and a subland is formed at a position corresponding to the subland of the land for surface mounting. 1) The via holes are connected between the sub-brands of the wiring layers, and the main lands of the (n-1) -th wiring layer and the main lands of the (n-2) -th wiring layer are connected via the via holes. The land and the subland are connected alternately by the via hole, and are connected to the wiring by the main land or the subland of the (nm) wiring layer which is the lower wiring layer of the via hole. (Where n is a natural number of 3 or more and m is a natural number of 2 or more and less than n). 2. An angle between a line connecting the center of the surface mounting land and the center of the closest surface mounting land, and a line connecting the center of the surface mounting land and the center of the subland is substantially equal. 2. The multilayer printed wiring board according to claim 1, wherein the angle is 45 degrees.