JPH10135648A - Multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer printed wiring board which can be formed in an even thickness and can be free from a warp and a twist due to heat at the time of assembling. SOLUTION: Each layer of this multilayer printed wiring board is divided into a wiring region 101 and a nonwiring region 102. In the nonwiring region 102, conductor foils (copper foils) 103 for controlling the warp are formed at a certain space from conductors of the wiring region 101 and at least 0.3mm inside the outer shape of the product. The conductor foils have any widths and any lengths and are so arranged that the conductor foil-free sections may be formed zigzag in each of the odd-numbered layers and the even-numbered layers. And, through holes 104 are formed to connect the conductor foils 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of a multilayer printed wiring board, and more particularly to a structure of a multilayer printed wiring board for bookshelf mounting used in an information communication system.

[0002]

2. Description of the Related Art In general, a multilayer printed wiring board of this type has conventionally been designed and manufactured so that the area where the wiring is possible is set to the inside (about 5 mm) of the gap between the guide rail and the conductor foil from the external dimensions.

[0003]

However, in the case of the above-mentioned conventional multilayer printed wiring board, when the size of the printed wiring board is increased, the printed board is largely warped by parts and its own weight in a reflow soldering process at the time of assembly. It will not return to its original state. In the flow soldering step, thermal expansion and contraction in the cooling step occur when only the soldering surface is exposed to a solder temperature of about 240 ° C. for several seconds. Due to the difference in the conductor density distribution and the component mounting distribution of the printed wiring board, the degree of shrinkage after thermal expansion differs due to the temperature distribution, causing warpage and twisting.
There are practically the following problems.

(1) On a double-sided printed wiring board, when mounting is performed on one side after reversing and mounting on the other side, the control position of the automatic mounting machine in the height direction is different. Problems such as a large displacement occur. (2) When the bookshelf is mounted, the printed wiring board comes off the guide rail. In the worst case, a short circuit accident occurs between adjacent printed wiring boards.

(3) At the time of bookshelf mounting, when the printed wiring board is inserted or removed, the printed wiring board collides with a component of an adjacent printed wiring board, and a component such as a missing surface component is damaged. SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer printed wiring board which can eliminate the above problems, make the thickness uniform, and prevent warpage and twisting due to heat during assembly.

[0006]

According to the present invention, there is provided a multi-layer printed wiring board having an arbitrary width, an arbitrary length, an arbitrary length between a wiring region and a product outer shape. The conductor foils having gaps are arranged so that the even-numbered layers and the odd-numbered layers have no zigzag portions without the conductor foils, and the conductor foils are connected by through holes.

Therefore, by arranging the conductor foil around the multilayer printed wiring board, the amount of resin in the portion without the conductor foil increases by the thickness of the conductor foil, and the dimensional change in that portion increases. It is possible to avoid warpage and torsion caused by heat at the time of assembling. (2) A conductive foil having an arbitrary width, length, and gap is provided in a non-wiring area between the wiring area and the outer shape of the product, and a portion without the conductive foil is arranged in a zigzag manner between an even layer and an odd layer. It is something to do.

Therefore, by arranging the conductor foil around the multilayer printed wiring board, the amount of resin in the portion without the conductor foil increases by the thickness of the conductor foil, and the dimensional change in that portion increases. This makes it possible to smoothly control the outflow of the etchant during circuit formation and the outflow of the molten adhesive during multilayer lamination.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic sectional view of a multilayer printed wiring board showing a first embodiment of the present invention, FIG. 2 is a schematic plan view of an odd layer of the multilayer printed wiring board,
FIG. 3 is a schematic plan view of an even layer of the multilayer printed wiring board.

[0010] As shown in these figures, each layer of the multilayer printed wiring board includes a wiring area 101 and a non-wiring area 10.
Divided into two. In this embodiment, the non-wiring area 102
Then, a conductor foil (copper foil) 103 for controlling warpage is connected to the wiring region 10.
Provide a certain gap with one conductor and 0.3
mm or more, a conductor foil 103 having an arbitrary width and an arbitrary length is formed in an odd-numbered layer and an even-numbered layer so that a portion without the conductor foil becomes zigzag. Are formed so as to be connected.

Here, the conductor foil 103 is placed at a distance of 0.1 mm from the outer shape of the product.
The reason why they are arranged at a position where 3 mm or more is secured is to prevent a router bit from hitting the conductive foil 103 during external processing and being broken when a multilayer board is used. Further, the conductor foil 103 having an arbitrary length
The reason for this is to allow bubbles generated when the adhesive (prepreg) is melted during multilayer lamination to escape to the outside of the product together with the outflow of the resin.

Also, the reason why the conductor foil 103 is arranged in a zigzag position in the even-numbered layer and the odd-numbered layer is that the resin amount in the portion without the conductor foil increases by the thickness of the conductor when the same location is used. This is to avoid an increase in the dimensional change of that portion. Furthermore, the reason why the through holes 104 are provided is to suppress expansion and compression between the portions. In addition, the hole is extended halfway or through, and the through-hole plated part is swollen and expanded.
This is to release the contraction and correct the warpage and twist.

As described above, according to the first embodiment, in the multilayer printed wiring board, the conductor foil having an arbitrary width and an arbitrary length outside the wiring area of the product and inside 0.3 mm from the outer shape of the product. 103 is an even-numbered layer, an odd-numbered layer, and a portion having no conductive foil is provided in a zigzag manner.
In the case where warping or torsion occurs due to the heat of assembly, a through hole 104 having a large warp or torsion is formed to a half of the plate thickness, or
By penetrating the entire substrate, the strain caused by the difference in thermal expansion of the base material is released, so that the warpage and the twist can be corrected, and the warpage and the twist of the large-sized substrate can be largely controlled.

[0014] Further, thickness variations between layers using an adhesive base material (prepreg) due to different wiring densities of the respective signal layers are suppressed so as to be small, so that a multilayer printed wiring board requiring characteristic impedance control is required. Can also be used. Next, a second embodiment of the present invention will be described. FIG. 4 is a schematic plan view of an odd-numbered layer of a multilayer printed wiring board showing a second embodiment of the present invention, and FIG. 5 is a schematic plan view of an even-numbered layer of the multilayer printed wiring board. The cross-sectional view is the same as that of FIG.

As shown in these figures, in each layer of the multilayer printed wiring board, a wiring area 201 and a non-wiring area 202
Is divided into In this embodiment, the non-wiring area 202
The conductor foil 203 for controlling the outflow of the etchant and controlling the outflow of the molten adhesive at the time of multilayer lamination is provided with an arbitrary gap from the conductor in the wiring area 201, and in an area where the outer diameter is secured by 0.3 mm or more from the outer shape of the product. The conductor foil having an arbitrary width, length, and gap was configured so that the inner portion of the conductor foil became zigzag for each of the odd-numbered and even-numbered layers.

Here, the conductor foil is 0.3 mm from the outer shape of the product.
Placed in the position secured above is a multilayer board,
This is to prevent the router bit from hitting the conductor foil during the outer shape processing and causing breakage due to misalignment between layers.
Furthermore, the conductor foil having an arbitrary length and gap is
When the pattern is formed with an etching solution, the outflow speed of the etching solution is made equal between the central portion and the end portion of the printed wiring board. In addition, air bubbles generated when the adhesive (prepreg) at the time of multilayer lamination is melted are allowed to escape to the outside of the product together with the outflow of the resin, and the finished board thickness at the center and the end of the printed wiring board is made uniform. That's why.

Further, the reason why the conductor foil is formed into a zigzag between the even-numbered layer and the odd-numbered layer is that, when performed at the same location, the resin amount in the portion without copper foil becomes thicker by the thickness of the copper foil. This is for avoiding an increase in the dimensional change of that portion. As described above, according to the second embodiment, in the multilayer printed wiring board, the conductor foil having an arbitrary width, length, and gap is formed in an even number of layers outside the wiring region of the product and inside 0.3 mm from the outer shape of the product. By providing the odd-numbered layers so that the portions without the copper foil form a zigzag pattern, the conductor width at the center portion and at the end portion during pattern formation becomes uniform. Further, the interlayer thickness after lamination becomes uniform at the center and the end.

Therefore, variation in characteristic impedance can be extremely reduced. Also, in the assembly process of mounting components on the printed wiring board, warpage due to component weight, own weight, and heat of soldering of the printed wiring board can be suppressed.

In the above embodiment, a multilayer printed wiring board for bookshelf mounting has been described. However, the present invention can be applied to all multilayer printed wiring boards using a lamination press in which a circuit is formed by etching. For example, the present invention can be applied to all types of multilayer printed wiring boards using a subtractive method. Further, the present invention is not limited to the above-described embodiments, and various modifications are possible based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0020]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first aspect of the present invention, by arranging the conductor foil around the multilayer printed wiring board, the amount of resin in the portion without the conductor foil is increased by the thickness of the conductor foil, and the amount of resin in that portion is increased. It is possible to avoid an increase in the dimensional change, and it is possible to correct warpage and torsion due to heat during assembly by zagging the plating of the through-hole portion.

(2) According to the second aspect of the invention, by disposing the conductive foil around the multilayer printed wiring board,
The amount of resin in the portion without the conductor foil is increased by the thickness of the conductor foil, making it possible to avoid an increase in dimensional change in that portion. Outflow control of the molten adhesive can be performed smoothly.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a multilayer printed wiring board according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view of an odd-numbered layer of the multilayer printed wiring board according to the first embodiment of the present invention.

FIG. 3 is a schematic plan view of an even-numbered layer of the multilayer printed wiring board according to the first embodiment of the present invention.

FIG. 4 is a schematic plan view of an odd-numbered layer of a multilayer printed wiring board according to a second embodiment of the present invention.

FIG. 5 is a schematic plan view of an even-numbered layer of a multilayer printed wiring board according to a second embodiment of the present invention.

[Explanation of symbols]

 101, 201 Wiring area 102, 202 Non-wiring area 103, 203 Conductor foil (copper foil) 104 Through hole

Claims (2)

[Claims] 1. An arbitrary width between a wiring area and a product outer shape.
Arrange the conductor foil with any length and any gap so that even-layer, odd-layer with no conductor foil is zigzag,
A multilayer printed wiring board, wherein the conductor foils are connected by through holes. 2. A conductive foil having an arbitrary width, length, and gap is provided in a non-wiring area between a wiring area and a product outer shape, and a portion without a conductive foil is zigzag between even and odd layers. A multilayer printed wiring board characterized by being arranged on a printed circuit board.