JPH11135953A - Multilayer printed wiring board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the warp due to shrinkage of a prepreg by providing a prepreg impeded from shrinking during heat pressure molding. SOLUTION: Two printed boards 1 are adhered such that a prepreg 2 is set between the boards 1, they are positioned and laminated, without deviation thereof, using laminating outputting reference pins 3, fixed to a laminate die 4, molded with hot plates 5 by the heat pressure molding to form a multilayer printed wiring board. Such printed wiring board impedes the prepreg 2 from shrinking to reduce resulting warp. This facilitates inserting/drawing connectors, etc., to/from the wiring board and lessens the trouble at automated process steps for mounting components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer printed wiring board and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventional multi-layer printed wiring boards usually have the same shape or cross section as the pin at a position corresponding to a positioning reference pin for lamination in a laminating mold for hot-press molding in order to perform positioning. There has been known one formed of a plurality of printed circuit boards, prepregs, and the like having reference holes of a similar shape.

[0003] The prepreg is obtained by impregnating a substrate made of glass cloth or the like with a thermosetting resin and drying it, and is used as a bonding sheet. A printed circuit board is obtained by laminating a plurality of prepregs and forming a predetermined circuit pattern on one or both sides of a substrate obtained by hot-press molding, or a plurality of these sheets formed by hot-press molding through a prepreg and integrated. It is.

[0004] Then, they are set in a lamination mold for hot pressing and hot pressing is performed. Pressurization is
It was performed at a constant pressure from the beginning, or switched to a higher pressure from a time determined from a change in viscosity or the like.

[0005] For the positioning reference pins for lamination, "Latest high-density printed wiring board technology" (Mimamatsu Data System) p751 to p752, and for the pressurization method, "Printed Circuit Handbook" (Kindai Kagakusha) p23-13 to It is detailed in p23-16.

[0006]

However, since the resin of the prepreg used as the bonding sheet is uncured, a larger shrinkage occurs during heating than the printed circuit board made of the thermosetting resin. .

However, in such a conventional multilayer printed wiring board, since the reference hole uses a prepreg having the same shape as the positioning reference pin for lamination in the lamination mold for hot pressing, the shrinkage is hindered and the printing is prevented. When bonded to a substrate, there is a problem that stress is generated in the multilayer printed wiring board and warpage occurs.

Further, in such a conventional pressing method, when heated, the prepreg is pressurized at a high pressure before the prepreg is sufficiently contracted, thereby inhibiting the contraction. There is also a problem that stress is generated in the printed wiring board and warpage occurs.

The present invention has been made in view of the above-mentioned facts, and has as its object to provide a multilayer printed wiring board capable of reducing warpage caused by shrinkage of a prepreg, and a method of manufacturing the same. Is to do.

[0010]

According to a first aspect of the present invention, there is provided a multilayer printed wiring board having a structure including a printed circuit board (1) having a circuit pattern formed on one side, both sides or inside thereof and a prepreg (2). In the multilayer printed wiring board obtained by performing the above-mentioned positioning and performing the hot pressing, the prepreg (2) having a shape in which the inhibition of the shrinkage during the hot pressing is reduced.

According to a second aspect of the present invention, there is provided a multilayer printed wiring board comprising a plurality of printed circuit boards (1) in a lamination mold (4) having lamination positioning reference pins (3) for performing the hot-press molding. ) And prepreg (2), etc., when the outer edge is in contact with a plurality of positioning reference pins (3) for lamination,
It has a prepreg (2) that can perform positioning.

According to a third aspect of the present invention, there is provided a multilayer printed wiring board including a plurality of printed circuit boards (1) in a lamination mold (4) having lamination positioning reference pins (3) for performing the hot-press molding. ) And a prepreg (2), etc., have a concave positioning portion or a reference hole for lamination such that the positioning reference pin (3) is in contact with the center side of the prepreg (2).
It is characterized by having a prepreg (2) by which positioning can be performed.

According to a fourth aspect of the present invention, there is provided a multilayer printed wiring board comprising a plurality of printed circuit boards (1) in a lamination mold (4) having lamination positioning reference pins (3) for performing the hot pressing. ) And a prepreg (2), etc., are laminated in an oval shape that is long in the direction of the vector sum of the contraction directions of the prepreg (2), and the center side of the oval prepreg (2) serves as a positioning reference pin (3) for lamination. It is characterized by having a prepreg (2) having a reference hole for lamination at a position where it is in contact with and capable of performing positioning by using them.

According to a fifth aspect of the present invention, there is provided a multilayer printed wiring board comprising a plurality of printed circuit boards (1) in a lamination mold (4) having lamination positioning reference pins (3) for performing the hot-press molding. ) And a prepreg (2), etc., are characterized by having a prepreg (2) having a lamination reference hole having a large diameter by a predetermined amount so that positioning can be performed by using them.

According to a sixth aspect of the present invention, there is provided a method for manufacturing a multilayer printed wiring board, comprising a printed circuit board (1) having a circuit pattern formed on one side, both sides or inside thereof and a prepreg (2), and positioning them. Then, in the method for manufacturing a multilayer printed wiring board manufactured by performing hot pressing, a low pressure is applied from the start of the contraction of the prepreg (2) to the time when the contraction of the prepreg (2) is maximized during the hot pressing. The method includes a step of pressurizing and, after that time, a step of applying a pressure higher than the above pressure.

According to a seventh aspect of the present invention, there is provided a method for manufacturing a multilayer printed wiring board, comprising a step of reaching a maximum temperature by the time of switching to a high pressure.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings according to embodiments.

FIG. 1 is a schematic cross-sectional view showing a state of a multilayer printed wiring board according to an embodiment of the present invention at the time of hot pressing.
FIG. 2 is a schematic plan view showing the relationship between the shape of the prepreg and the positioning reference pins for lamination according to the first embodiment of the present invention. FIG. 3 is a schematic plan view showing the relationship between the shape of the prepreg and the positioning reference pins for lamination according to the second embodiment of the present invention. FIG. 4 is a schematic plan view showing the relationship between the shape of the prepreg and the positioning reference pins for lamination according to the third embodiment of the present invention. FIG. 5 is a schematic plan view showing details of a reference hole shape for lamination of a prepreg according to a third embodiment of the present invention. FIG. 6 is a schematic plan view showing the relationship between the shape of the prepreg and the positioning reference pins for lamination according to the fourth embodiment of the present invention. FIG. 7 is a graph showing pressure control conditions when performing hot pressing according to the fifth embodiment of the present invention. FIG. 8 is a graph showing a relationship between a pressure control condition and a temperature control condition when performing hot pressing according to the sixth embodiment of the present invention. FIG. 9 is an analysis model diagram used for a warpage comparison simulation of the multilayer printed wiring board according to the embodiment of the present invention.

As described above, FIG. 1 shows a state at the time of hot press molding. In this embodiment, a case where two printed boards (1) are bonded is shown. The prepreg (2) is sandwiched between the printed circuit boards (1), and using the positioning reference pin (3) for lamination, the alignment is performed so that each material does not shift, and the layers are laminated. Fix it. Next, these are hot-pressed with a hot plate (5) to form a multilayer printed wiring board.

First, a first embodiment of the present invention will be described. As shown in FIG. 2, when the printed circuit board (1) and the prepreg (2) are laminated, a prepreg (2) whose outer edge is in contact with eight positioning reference pins (3) for lamination is used. Positioning is performed by contacting the reference pin (3), and hot pressing is performed by a conventional pressing method.
Form a multilayer printed wiring board. The positioning of the printed circuit boards (1) is accurately performed by passing the reference holes for lamination through the positioning reference pins (3), and the prepreg (2) is positioned by contacting the positioning reference pins (3). Thereby, the direction, position, etc. of the prepreg (2) can be substantially determined, and the prepreg (2) contracts without being hindered by the positioning reference pins (3) when the prepreg (2) contracts. Can be suppressed.

As for the pressing conditions, warping can be further suppressed by adopting a manufacturing method as described in a fifth embodiment or a sixth embodiment described later.

Next, a second embodiment of the present invention will be described. As shown in FIG. 3, when the printed circuit board (1) and the prepreg (2) are laminated, the prepreg (2) is located at a position corresponding to the lamination positioning reference pin (3). ) Using a prepreg (2) having a concave positioning portion whose center side is in contact with, and performing positioning by contacting the positioning reference pin (3) for lamination, performing hot pressing with a conventional pressing method, and forming a multilayer printed wiring board. To form The positioning of the printed circuit boards (1) is accurately performed by passing the reference holes for lamination through the positioning reference pins (3), and the prepreg (2) is positioned by contacting the positioning reference pins (3). Thus, the direction and position of the prepreg (2) can be substantially determined, and the prepreg (2) shrinks without being hindered by the positioning reference pins (3) when the prepreg (2) shrinks, and warps the multilayer printed wiring board. Can be suppressed.

In the case of this embodiment, warping can be further suppressed by using a manufacturing method such as the fifth embodiment or the sixth embodiment described below as the pressing condition.

Next, a third embodiment of the present invention will be described. As shown in FIGS. 4 and 5, when the printed circuit board (1) and the prepreg (2) are laminated, the prepreg (2) has an oval shape that is long in the direction of the vector sum of the contraction directions. 2) A prepreg (2) having a lamination reference hole whose center side is in contact with the lamination positioning reference pin (3) is used, and positioning is performed by contacting the lamination hole with the lamination positioning reference pin (3). Hot-press molding is performed by a conventional pressing method to form a multilayer printed wiring board. The positioning between the printed circuit boards (1) is accurately performed by passing the reference holes for lamination through the positioning reference pins for lamination, and the prepreg is positioned by bringing the prepreg (2) into contact with the positioning reference pins (3) for lamination. The direction and position of (2) can be almost determined, and when the prepreg (2) shrinks, it is shrunk without being hindered by the positioning reference pins (3) for lamination, and warpage of the multilayer printed wiring board is suppressed. Can be.

The dimension a shown in FIG. 5 represents one half of the maximum shrinkage when the prepreg (2) is heated in the x direction shown in FIG. 4, and the dimension b shown in FIG.
Represents one half of the maximum shrinkage when the prepreg (2) is heated in the y direction shown in FIG.

Also in the case of this embodiment, warping can be further suppressed by using a manufacturing method such as the fifth embodiment or the sixth embodiment described below as the pressing condition.

Next, a fourth embodiment of the present invention will be described. As shown in FIG. 6, when the printed board (1) and the prepreg (2) are laminated, a prepreg (2) having a lamination reference hole having a large diameter by a predetermined amount is used by a lamination positioning reference pin (3). The positioning is performed by bringing the reference hole into contact with the positioning reference pin (3) for lamination, and hot pressing is performed by a conventional pressing method to form a multilayer printed wiring board. The positioning of the printed circuit boards (1) is accurately performed by passing the reference hole for lamination through the positioning reference pin (3) for lamination, and the prepreg (2) is positioned on the reference pin (3) for lamination.
Prepreg (2) by positioning by touching
Can be substantially determined, and when the prepreg (2) shrinks, the shrinkage occurs without being hindered by the positioning reference pins (3) for lamination, and the warpage of the multilayer printed wiring board can be suppressed.

In the case of this embodiment, warping can be further suppressed by using a manufacturing method such as a fifth embodiment or a sixth embodiment described below as a pressing condition.

Next, a fifth embodiment of the present invention will be described. In the case of this embodiment, a time t2 at which the shrinkage of the prepreg (2) of the same kind as that used is the maximum [the size of the prepreg (2) is the minimum] is determined in advance under the same temperature conditions as during molding. It is something to check.

According to the pressure control conditions at the time of performing the hot press forming as shown in FIG. 7, when the prepreg (2) shrinks, the inhibition due to the high pressure load is reduced, so that the shrinkage occurs and the multilayer printed wiring board is shrunk. Warpage can be suppressed.
The time t1 shown in FIG. 7 is the time at which the prepreg (2) starts contracting.

Similarly, a sixth embodiment of the present invention will be described. In the case of this embodiment, the hot plate (5) is preheated to the maximum temperature [control temperature] T1 in advance. When the lamination mold (4) for hot pressing is set, variations in the way heat is transmitted to each part are reduced, and as a result, variations in shrinkage are minimized. According to the temperature control conditions for performing the hot-press forming as shown in FIG. 8, at the time of pressurization at the time t2 when the prepreg (2) contracts at a maximum, the partially unshrinked portion of the prepreg (2) decreases. Therefore, the inhibition of the prepreg (2) from shrinking is further reduced than in the case of the fifth embodiment, and the warpage of the multilayer printed wiring board can be suppressed. The time t1 shown in FIG. 8 is the time at which the prepreg (2) starts contracting.

With respect to the multilayer printed wiring board of the above embodiment, a simulation for comparing the degree of warpage was performed. As described above, this analysis model is
Is shown in

As the dimensional change of the printed circuit board (1) and the prepreg (2) used in the simulation, values obtained by actual TMA measurement under molding temperature conditions are used.

However, as the printed circuit board (1), a circuit board on which a circuit pattern is not formed in both actual measurement and simulation is used. Other physical property values and the like necessary for the simulation use the general values of the main materials constituting them. The material is prepreg (2)
In the case of (1), the substrate is made of glass cloth and a thermosetting resin is made of epoxy resin. The printed circuit board (1) is also made of glass cloth and epoxy resin. The size of the printed board (1) or the prepreg (2) is, for example, 255 mm square for both the printed board (1) and the prepreg (2), and the thickness of the printed board (1) is 0.4 mm on the upper side. , Lower 0.3 mm, and the thickness of the prepreg (2) is 0.1 mm.

In the present embodiment, it is assumed that the printed circuit board (1) is adhered after the prepreg (2) is maximally contracted.
The maximum value of the dimensional change after the maximum time of prepreg (2) shrinkage measured under the same temperature conditions as during molding (mainly, the amount of dimensional change when the temperature of the apparatus is lowered after the completion of hot pressing) is used for analysis. . For the printed circuit board (1) as well, the maximum value of the dimensional change after the maximum prepreg (2) contraction time is used.

As a comparison of this embodiment, the prepreg (2) and the printed circuit board (1) from the beginning to the end of the heat-pressure process
Is used.

The other conditions are the same in the embodiment and the comparison. The maximum amount of warpage of each of such analysis results is 0.84 mm in the case of the embodiment.
And 3.90 mm for comparison. Here, the maximum amount of warpage is the difference between the maximum amount of change in the stacking direction in the positive direction and the maximum amount of change in the negative direction.

From the above, it can be said that the multilayer printed wiring board of the present invention and the method of manufacturing the same are effective in reducing the warpage caused by the inhibition of the contraction of the prepreg (2).

[0039]

The multilayer printed wiring board according to the first aspect of the present invention is effective in reducing warpage caused by the inhibition of prepreg shrinkage.

Further, the warpage generated in the multilayer printed wiring board can be reduced without changing the physical properties of the materials used conventionally and without changing the shape of the device.

Further, since the warpage is reduced, a connector or the like can be easily inserted into or removed from the multilayer printed wiring board, and the effect of significantly reducing troubles in the process of automatically mounting components can be obtained. .

In the multilayer printed wiring board according to the second aspect of the present invention, in addition to the effect of the first aspect, the prepreg can have a simple shape because there is no reference hole for lamination usually provided in the prepreg.

The multilayer printed wiring board according to claim 3 of the present invention has the effect of claim 1, and can be positioned with a small number of positioning reference pins for lamination. It will not be done.

In the multilayer printed wiring board according to the fourth aspect of the present invention, in addition to the effects of the first aspect, positioning can be performed with a small number of positioning reference pins for lamination, and the prepreg is passed through the positioning reference pins for lamination. After that, the entire position does not change due to causes other than shrinkage.

In the multilayer printed wiring board according to claim 5 of the present invention, in addition to the effect of claim 1, positioning can be performed with a small number of positioning reference pins for lamination, and processing of the lamination reference holes is easy. is there.

The method for manufacturing a multilayer printed wiring board according to claim 6 of the present invention is effective in reducing the warpage caused by the inhibition of the prepreg shrinkage.

According to the method of manufacturing a multilayer printed wiring board according to claim 7 of the present invention, in addition to the effect of claim 6, a higher effect can be obtained only by changing the timing of temperature control. In addition, variations in partial warpage and torsion are reduced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a state of a multilayer printed wiring board according to an embodiment of the present invention at the time of hot pressing.

FIG. 2 is a schematic plan view showing the relationship between the shape of a prepreg and a positioning reference pin for lamination according to the first embodiment of the present invention.

FIG. 3 is a schematic plan view showing the relationship between the shape of a prepreg and a positioning reference pin for lamination according to a second embodiment of the present invention.

FIG. 4 is a schematic plan view showing the relationship between the shape of a prepreg and a positioning reference pin for lamination according to a third embodiment of the present invention.

FIG. 5 is a schematic plan view illustrating details of a reference hole shape for lamination of a prepreg according to a third embodiment of the present invention.

FIG. 6 is a schematic plan view showing the relationship between the shape of a prepreg and positioning reference pins for lamination according to a fourth embodiment of the present invention.

FIG. 7 is a graph showing pressure control conditions when performing hot pressing according to a fifth embodiment of the present invention.

FIG. 8 is a graph showing a relationship between a pressure control condition and a temperature control condition when performing hot pressing according to a sixth embodiment of the present invention.

FIG. 9 is an analysis model diagram used for a warpage comparison simulation of the multilayer printed wiring board according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 printed circuit board 2 prepreg 3 positioning reference pin for lamination 4 lamination mold

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keishi Shibata 1048 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Works, Ltd.

Claims (7)

[Claims] 1. A multilayer printed wiring board having a printed circuit board and a prepreg having a circuit pattern formed on one side, both sides or inside thereof, and positioning them, and performing hot press forming on the multilayer printed wiring board. A multilayer printed wiring board comprising a prepreg having a shape in which inhibition of shrinkage is reduced. 2. When laminating a plurality of printed circuit boards and prepregs in a lamination mold having lamination positioning reference pins for performing the above-mentioned hot pressing, an outer edge is in contact with a plurality of lamination positioning reference pins. 2. The multilayer printed wiring board according to claim 1, further comprising a prepreg capable of performing positioning. 3. When laminating a plurality of printed circuit boards and prepregs in a lamination mold having lamination positioning reference pins for performing the hot-press forming, the lamination positioning reference pins are in contact with the prepreg center side. 2. The multilayer printed wiring board according to claim 1, further comprising a prepreg having a concave positioning portion or a reference hole for lamination and capable of performing positioning by using the positioning portion. 4. When laminating a plurality of printed circuit boards and prepregs in a lamination mold having positioning reference pins for lamination for performing the hot-press molding, a long length in the direction of the vector sum in the shrinkage direction of the prepreg is used. 2. The prepreg according to claim 1, wherein the prepreg has a circular shape, has a reference hole for lamination at a position where the center side of the oval prepreg is in contact with the positioning reference pin for lamination, and can perform positioning using the reference holes. Multilayer printed wiring board. 5. A method for laminating a plurality of printed boards and prepregs in a lamination mold having positioning reference pins for lamination for performing the above-mentioned hot-press forming, wherein a lamination reference hole having a predetermined diameter and a large diameter is provided. 2. The multilayer printed wiring board according to claim 1, further comprising a prepreg capable of performing positioning using the prepreg. 6. A method for manufacturing a multilayer printed wiring board, comprising a structure including a printed circuit board and a prepreg having a circuit pattern formed on one side, both sides or inside thereof, positioning them, and performing hot-press molding. From the start of shrinking of the prepreg to the time at which shrinkage of the prepreg is maximized during hot-press molding, and after that time, a step of applying a higher pressure than the above-mentioned pressure. Plate manufacturing method. 7. The method according to claim 6, further comprising the step of reaching a maximum temperature by the time of switching to the high pressure.
A method for producing the multilayer printed wiring board according to the above.