JPH02292897A - Manufacture of multilayer printed board and measuring jig plate - Google Patents

Abstract

PURPOSE:To enable a multilayer printed board to be free of interlaminar bubbles and interlaminar deviation by a method wherein pressure measuring elements are disposed on the face of jig plate in contact with a laminated body to measure the distribution of pressure of the molten insulating adhesive agent so as to determine an bonding condition. CONSTITUTION:A printed wiring board 1A whose pressure distribution is to be measured and an insulating adhesive agent 1B are alternately laminated to form a laminated body 1, and the laminated body 1 is pinched between a measuring jig plate 4 composed of an upper jig plate 2 and a lower jig plate 3. Pressure measuring elements 5 used for measuring the pressure of the molten insulating adhesive agent 1B are disposed in lattice on the lower jig plate 3. When the measuring jig plate 4 is inserted into a hot press 6 and hot-pressed, the adhesive agent 1B is fused to start flowing out to a peripheral part. At this point, the output signals of the pressure measuring elements 5 are taken out, and the signals amplified by an amplifier 7 are recorded in a recorder 8 to record the change of the adhesive agent in pressure distribution. Basing on the measured result, a proper bonding condition can be easily determined.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention involves inserting a multilayer body made by alternately stacking printed wiring boards and an insulating adhesive between hot plates, The present invention relates to a method of molding the multilayer body by pressurizing the multilayer body through a hot plate, for example, a method of molding a multilayer printed board for a large computer/equipment.

[Conventional technology]

The multilayer printed board for a large-sized computer according to the present invention has a thickness of about 0.2 nm, which is very thin, and a size of 300
It is large, measuring 300mm x 500 x 500+++n+, and has 20 to 40 layers.

FIG. 9 shows a cross-sectional view of one printed wiring board, and the printed wiring board IA is constructed by bonding conductors to both sides of an insulating resin board, and the thickness of each is equal to that of the insulating resin board. The resin plate is about 0.1mm thick, and the conductor copper foil is about 0.05mm thick.
mm (on one side) and is very thin, so it is easily deformed by the influence of pressure and heat.

FIG. 10 shows the printed wiring board IA and the insulating adhesive I.
It is a perspective view which shows an example of the laminated body which overlapped and laminated|stacked B alternately. Conventional methods, in which a large number of extremely thin printed wiring boards are stacked and subjected to heat and pressure, have the following problems.

When heat is applied to the laminate under pressure, the insulating adhesive that makes up the laminate melts due to the heat.

According to the authors' research, the pressure distribution of the molten resin at this time is high in the center of the plane and low in the periphery, as shown in FIG.

Each printed wiring board that makes up the laminate has the following resistance to heat:
Since it is a very unstable material compared to metal and is also very thin, deformation occurs within the plane of the substrate due to heating and pressure during bonding and the effects of the pressure distribution. The degree of wiring on each printed wiring board differs depending on the role of the wiring board (for example, a wiring board that supplies power to each printed wiring board, a wiring board that only performs signal processing, etc.), so the degree of wiring for each printed wiring board differs depending on the role of the wiring board (for example, a wiring board that supplies power to each printed wiring board, a wiring board that only performs signal processing, etc.). , coefficient of linear expansion, temperature dependence of rigidity of the base material) are also different. Of course, the degree of deformation in response to pressure also differs. For this reason, since the amount of deformation between each printed wiring board is different, an interlayer deviation occurs between each printed wiring board.

On the other hand, since the wiring density of printed boards for large computers is generally very high, the board has a large number of uneven conductor surfaces. For this reason, many gaps (spaces) occur in the laminate. If gas remains in this gap, when the laminate is heated and pressurized, the gas in this space may be engulfed by the molten insulating adhesive and may not be able to flow out of the laminate. Therefore, after the molten insulating adhesive hardens, voids (bubbles) may remain.

Such air bubbles may cause electrical conductivity in unnecessary areas due to plating after drilling through holes for establishing electrical conduction between the eyebrows, and thus are likely to cause defects in the multilayer printed board.

Conventionally, the following methods have been used to solve the problem of occurrence of interlayer displacement and residual bubbles.

For example, as described in Japanese Unexamined Patent Publication No. 59-87894, a cylinder for controlling the distance between the hot plates and a displacement detector are provided between each hot plate, and the distance between the hot plates detected by the displacement detector is By inputting it into the controller, calculating the parallelism, finding a parallelism correction value, converting this correction amount to pressure, and issuing a command value to the pressure control valve of the cylinder for controlling the parallelism between the hot plates, The parallelism between the hot plates is maintained, and in-plane misalignment between the printed boards of the multilayer printed board, that is, interlayer misalignment, can be suppressed.

In addition, as a method to prevent air bubbles remaining between the eyebrows, the gas between the hot plates is degassed, a vacuum is created, and the pressure is applied.
Examples include JP-A-57-118698.

In addition, a method developed by Japanese Patent Laid-Open No. 2003-11102 does not use a hot plate, but instead places the laminate in a heat-resistant film, vacuums the inside of the film, and then places the film in a high-pressure tank and heats and pressurizes it using high-temperature, high-pressure gas. 62-18247 etc.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into account the following matters, and has a problem in that it cannot completely suppress glabella misalignment and glabellar air bubbles in the multilayer printed board.

■ After applying pressure to the jig plates holding the laminate, when the laminate is heated, the insulating adhesive that makes up the laminate melts. When a fluid substance is pressurized with a parallel plate such as a hot plate, the pressure of the molten insulating adhesive is distributed such that the pressure is high in the center of the plane of the printed wiring board and low in the periphery. have. Furthermore, the shape of this distribution changes over time. However, the pressure distribution of the insulating adhesive during bonding has not been measured, and the influence of the pressure distribution characteristics of the insulating adhesive on voids and misalignment is not reflected in actual bonding conditions.

(2) The pressure distribution changes depending on the shape of the substrate, the shape of the wiring, and the planar state of the hot plate of the adhesive press.

Therefore, in order to obtain the most appropriate pressure distribution, it is necessary to improve the flatness of the hot plate of the contact press, but since the pressure distribution of the insulating adhesive during bonding has not been measured,
Appropriate bonding conditions have not been determined. For this reason, a large number of adhesion experiments are required to determine the conditions.

The present invention solves the problems of the prior art described above, and measures the pressure distribution of the insulating adhesive during bonding using a measuring element with a very simple structure, and then determines the bonding conditions. The object of the present invention is to provide a method for forming a multilayer printed board without interlayer bubbles and interlayer displacement.

[Means to solve the problem]

In order to achieve the above object, pressure measuring elements are arranged in a grid pattern or radially within the surface of a jig plate that is in contact with the laminated body of a jig plate that clamps the laminated body of multilayer printed boards, and the pressure measuring elements are placed in a molten state. The pressure distribution of the molten insulating adhesive can be measured by directly touching the insulating adhesive.

In addition, since the pressure distribution of the molten insulating adhesive is affected by the flow of the resin, it is necessary to surround the insulating adhesive to be measured or use a sealing material to ensure that the molten insulating adhesive is This allows the pressure distribution to be measured while preventing outflow.

In addition, it consists of a frame with a seal that prevents gas from leaking between the upper and lower plates of the molten insulating adhesive, and a fluid such as a dryer is added to the space within this frame to apply the molten M-edge adhesive. This prevents the p-distribution from flowing out and allows the measurement of the p-distribution.

In addition, based on the pressure distribution of the molten insulating adhesive during bonding using the measurement jig plate, we conducted many experiments to determine the appropriate bonding conditions, for example, when the material of the insulating adhesive changes. The decision can be made without having to do the following.

[Effect]

The above measurement jig plate can measure the pressure distribution of the molten insulating adhesive during bonding, so it can be used, for example, when the substrate size changes, the material of the insulating adhesive changes, and press precision Adhesion conditions in the case where the precision of the plate is deteriorated can be determined based on the measurement of the pressure distribution. Therefore, the bonding conditions can be determined without conducting a large number of bonding experiments.

Furthermore, since the molten insulating adhesive directly contacts the pressure measurement element and measures it, the pressure distribution can be measured using a very inexpensive measurement jig plate.

Additionally, it is possible to stop the outflow of the molten insulating adhesive by placing an enclosure or a sealant around the insulating adhesive, so the pressure distribution can be measured when the outflow of the molten insulating adhesive is stopped. can.

In addition, the frame is equipped with a seal that prevents gas from leaking between the upper and lower plates, and the pressure distribution when a fluid such as dry air is added to the space within the frame to slow down the outflow of the molten insulating adhesive. can be taught.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3.

FIG. 1 shows an outline of a measurement jig plate according to the present invention, and 1 shows a laminate in which a printed wiring board IA whose pressure distribution is to be measured and a high-strength adhesive are alternately laminated. The molten insulating adhesive pressure distribution measuring jig plate 4 (hereinafter referred to as '#J) according to the present invention is composed of an upper jig plate 2 and a lower jig plate 3.
(referred to as fixed jig plate 4). On the lower jig plate 3,
Pressure measuring elements 5 for measuring the pressure of the melted insulating adhesive are arranged in a grid pattern.

FIG. 2 shows the measuring method of the present invention, in which the measurement jig plate 4 configured as shown in FIG. and laminate 1
The insulating adhesive IB constituting the material begins to melt and flow out to the outer periphery. At this time, the output signal of the measured pressure of the pressure measuring element 5 is extracted by a signal code, and is input to the amplifier 7 to be amplified. This amplified signal is recorded on a recorder 7 or a computer (not shown) to record changes over time in the pressure distribution of the molten insulating adhesive during hot press bonding. FIG. 3 shows the layer structure of the laminate 1, in which printed wiring boards IA and insulating adhesive IB are alternately stacked, and the bottom layer in contact with the pressure measuring element 5 shown in FIG. In order to directly transmit the pressure of the insulating adhesive IB during melting to the measurement element 5, the insulating adhesive IB is exposed and installed.

According to this embodiment, it is possible to measure the pressure distribution of the molten insulating adhesive during adhesion of objects similar to the actual layer structure, and to record changes in the pressure distribution over time. Also,
The pressure measurement element 5 of this measurement jig plate has a horizontal structure similar to that of a conventional pressure measurement element for measuring the pressure of a liquid.
This measurement jig plate can be manufactured at a very low cost.

Furthermore, using the measuring means, appropriate bonding conditions can be easily determined based on the measurement results. Below, the fourth
An example of setting appropriate bonding conditions will be described with reference to FIGS. 5, 6, 7, and 8.

FIG. 4 shows a record of changes over time in the pressure distribution of the melted insulating adhesive during bonding using the measuring jig plate 4 described in FIG. 1. Note that the size of the substrate and the insulating adhesive is 250 x 250 mm.

The position of the measurement point is 40 mm from the center point of the board toward the opposite side.
The results are extracted from four points in the front direction at am intervals.

As shown in FIG. 4, the pressure of the molten insulating adhesive changes with the passage of time after the start of adhesion.

The results of this measurement revealed the following.

■ Immediately after applying adhesive pressure, the pressure distribution is high in the center and low in the periphery.

■ As time elapses after applying adhesive pressure, the pressure at each measurement point decreases and becomes almost zero except for the pressure at the center point.

In this way, at the beginning of adhesion, the area of high pressure is large, centered around the center of the substrate, but as time passes, the area decreases and the area of low pressure increases. According to the authors' previous research, it has been found that interlayer voids tend to occur more often in areas where the pressure is low during bonding.The above measurement results indicate that the pressure in the peripheral area of the substrate is low from the start of bonding to the end. Therefore, it was found that voids were frequently generated.

In addition, with the heating temperature of the current bonding conditions, there are many places where the pressure drop occurs, so even near the center of the substrate,
It was found that voids may occur. this is,
This is because the viscosity decreases due to the high temperature, and the rate at which the molten insulating adhesive flows out to the outer periphery increases, resulting in a resin shortage within the laminate.

After elucidating the pressure distribution and the cause of the pressure drop in this way, the following appropriate bonding conditions were set.

■ The current heating temperature is to accelerate the curing of the molten insulating adhesive, but the viscosity of the molten insulating adhesive decreases as the temperature rises, and conversely increases as the temperature decreases. Therefore, we took advantage of this property and lowered the heating temperature for bonding. FIG. 5 shows the measurement results when bonding was performed at a heating temperature 40°C lower than the normal heating temperature. Although the distribution remains high in the center and low in the periphery,
The decrease in pressure over time became smaller.

■ The viscosity of the molten insulating adhesive is such that the viscosity increases over time at a constant heating temperature. Taking advantage of this property, the time to apply adhesive pressure was delayed. As a result (not shown), the same effect as in (2) above was obtained.

In this way, whereas conventionally it took a long time to determine the appropriate bonding conditions through trial and error through numerous experiments, the present invention allows This has the effect of being able to determine appropriate adhesion conditions in a short time through experiments.

Next, the pressure distribution that the pressure of the molten insulating adhesive around the substrate is low cannot be changed by simply changing the bonding conditions described above.
There was no change. Factors that change this pressure distribution include the surface accuracy of the press, the surface accuracy of the jig plate, and the pattern wiring of the board.According to the authors' research, it has been found that the pressure in the periphery can be reduced by the current molten insulating adhesive. It has been found that it is difficult to make the pressure distribution uniform with adhesive methods that allow the agent to flow out. Therefore, we proposed an adhesive method that stops the flow of molten insulating adhesive, which is the cause of pressure distribution.

FIGS. 6 and 7 are examples of measurement jig plates that can stop the outflow of the green-proofing adhesive.

FIG. 6 shows a cross section of the measuring jig plate according to the present invention, in which an outer frame 1 is placed around the laminate 1 sandwiched between the upper jig plate 9 and the lower jig plate 10.
1 and a sealing material 12 is installed inside it. When adhesive pressure is applied to the measurement jig plate, the molten insulating adhesive flows between the upper jig plate 9 and the lower jig plate 10, reaches the sealing material 12, and then flows into the molten insulating adhesive. The flow of agent is stopped. Therefore, the pressure distribution within the substrate surface, which occurs when the molten insulating adhesive flows out, is eliminated and becomes uniform.

Figure 7 shows a pressure measuring jig plate that can stop the flow of melted insulating adhesive using another method, and is designed to prevent gas from leaking between the upper jig plate 13 and the lower jig Fi14. Consisting of an outer frame 16 on which a sealing material l5 is installed,
Fluid pressure, such as dry air, can be applied to the space within this frame through the fluid addition port 17 to stop the outflow of the molten insulating adhesive. By adding dry air during bonding,
Since the pressure of the molten insulating adhesive increases, pressure gradients disappear and the pressure distribution becomes uniform.

FIG. 8 shows the measurement results when using such a measuring jig plate to stop the outflow of the molten insulating adhesive during bonding. This result was measured using the measurement jig plate described in FIG. 6. In addition, the board size is 250 x 250tm,
The measurement points were extracted from four points in the front direction at intervals of 401 m from the center point of the board toward the opposite side.

In this way, a pressure distribution occurs for a few seconds after the start of adhesion, but after that, the pressure becomes uniform and is maintained as it is. Therefore, since the adhesive is bonded under high pressure at the outer periphery, no voids occur, and the pressure distribution is uniform and the molten insulating adhesive does not flow, so there is little interlayer deviation. Furthermore, the seventh
Similar results can be obtained by using the measurement jig plate explained in the figure.

〔Effect of the invention〕

According to the present invention, as explained above, it is possible to measure the pressure distribution of the molten insulating adhesive during bonding, so it is not necessary to determine the appropriate bonding conditions by trial and error through numerous experiments. , can be determined in a small number of experiments, and has the effect of being able to determine the bonding conditions in a short time, reducing the number of experiments by about half.

Moreover, since the molten insulating adhesive is directly fused to the pressure measuring element to detect the pressure, there is an effect that the measuring jig plate can be provided at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a schematic diagram showing an embodiment of the present invention.
FIG. 3 is a schematic diagram showing the measurement method of the present invention, FIG. 3 is a perspective view showing the layer structure of the laminate according to the present invention, and FIG. 4 is a FIG. 5 is a diagram showing changes over time in the pressure distribution of the molten insulating adhesive inside, after setting appropriate bonding conditions according to the present invention.
A diagram showing changes in the pressure distribution of the molten insulating adhesive over time during bonding, and FIG. 6 is a schematic diagram of a pressure measuring jig plate that can stop the outflow of the molten insulating adhesive according to the present invention. , FIG. 7 is a schematic diagram of a pressure measuring jig plate that can stop the flow of melted insulating adhesive by another method, FIG. 8
The figure shows the change over time in the pressure distribution of the molten insulating adhesive during bonding using a pressure measuring jig plate that can stop the outflow of the molten insulating adhesive. FIG. 10 is a partial cross-sectional view of the printed wiring board according to the present invention, and FIG. 11 is a perspective view showing the laminate according to the present invention. FIG. 11 is a graph showing the pressure distribution of the molten insulating adhesive. Explanation of symbols 1...Laminated body, IA...Printed wiring board, 1B...
- Insulating adhesive, 2... Upper jig plate, 3... Lower jig plate, 4... Measuring jig plate, 5... Pressure measurement element, 6...
・Hot press, 7... Magnifier, 8... Record total 59
...Upper jig plate, 10...Lower jig plate, 11...Outer frame, 12...Sealing material, 13...Upper jig plate, 14...
・Lower jig plate, 15...Sealing material, 16...Outer frame, 1
7...Fluid addition port.躬Z Hanawa 44e Gin Kandai Saimo Kinen Gin Threshold 躬 8 Figures

Claims (4)

[Claims] 1. Multilayer printing is achieved by sandwiching a multilayered product made by stacking multiple printed wiring boards and insulating adhesives alternately between jig plates, inserting this between hot plates, and pressurizing and heating the multilayered product. A method for forming boards, which is characterized by measuring the in-plane pressure distribution of the molten insulating adhesive when bonding printed boards and the changes in this over time, then determining the bonding conditions and performing the bonding. A method for manufacturing a multilayer printed board. 2. A measurement jig plate for measuring the in-plane pressure distribution of an insulating adhesive and its changes over time, in which pressure measurement elements are arranged in a grid pattern or radially within the plane of the jig plate, A measuring jig plate characterized in that the pressure measuring element is directly brought into contact with a molten insulating adhesive. 3. In the jig plate for measuring the in-plane pressure distribution of the molten insulating adhesive and its change over time according to claim 2, an enclosure or a sealing material is installed around the insulating adhesive to be measured. A measurement jig plate characterized by having a structure that prevents molten insulating adhesive from flowing out. 4. In the jig plate for measuring the in-plane pressure distribution of the molten insulating adhesive and the change over time according to claim 2, the jig plate is provided with a frame provided with a seal to prevent gas from leaking between the upper plate and the lower plate. A measuring jig plate characterized in that it has a structure capable of adding a fluid such as dry air to the space within the frame and stopping the outflow of molten insulating adhesive.