JP3231537B2 - Method for manufacturing multilayer substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multi-layer substrate formed by connecting a plurality of circuit patterns.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and higher in density, multilayer substrates have been strongly demanded not only in industrial fields but also in consumer fields.

In particular, as the density of a multilayer substrate increases, circuit patterns become finer, and the lamination accuracy between circuit patterns of a plurality of layers affects the performance. Therefore, a lamination method having high productivity simultaneously with lamination accuracy is desired. It is rare.

A method of manufacturing a conventional multilayer substrate, here, a four-layer substrate will be described. First, a method for manufacturing a double-sided circuit board serving as a base of a multilayer board will be described. FIG.
(F) is a process sectional view of a conventional method for manufacturing a double-sided circuit board.

Reference numeral 1 denotes a prepreg sheet having a size of 250 mm square and a thickness of about 150 μm, for example, a base material (hereinafter referred to as an aramid-epoxy sheet) made of a composite material obtained by impregnating a non-woven aromatic polyamide fiber with a thermosetting epoxy resin. Is used.

Reference numeral 32 denotes a plastic sheet having a thickness of about 10 μm and coated with a Si-based release agent on one side. For example, polyethylene terephthalate (hereinafter referred to as a PET sheet) is used. Reference numeral 33 denotes a through hole, which is a 35 μm-thick Cu stuck on both surfaces of the aramid-epoxy sheet 1.
A conductive paste 2 electrically connected to a metal foil 4 such as a metal foil is filled.

First, as shown in FIG. 8 (b), a predetermined portion of the aramid-epoxy sheet 1 (FIG. 8 (a)) having PET sheets 32 adhered to both sides is penetrated by using a laser processing method or the like. A hole 33 is formed.

[0008] Next, as shown in FIG.
Is filled with a conductive paste 2. As a method of filling the conductive paste 2, an aramid having a through hole 33 may be used.
The epoxy sheet 1 is placed on a table of a printing machine (not shown), and the conductive paste 2 is directly printed on the PET sheet 32.

At this time, the PET sheet 32 on the upper surface plays a role of a printing mask and a role of preventing contamination of the surface of the aramid-epoxy sheet 1.

[0010] Next, as shown in FIG.
The PET sheet 32 is peeled off from both sides of the epoxy sheet 1.

[0011] Then, as shown in FIG. 8 (e), a metal foil 4 such as Cu is laminated on both surfaces of the aramid-epoxy sheet 1. By heating and pressing with a hot press in this state,
As shown in FIG. 8 (f), aramid-epoxy sheet 1
Is compressed (t2 = about 100 μm), the aramid-epoxy sheet 1 and the metal foil 4 are adhered, and the metal foils 4 on both sides are electrically conductive by the conductive paste 2 filled in the through holes 33 provided at predetermined positions. Connected.

Then, the metal foil 4 on both sides is selectively etched to form a circuit pattern (not shown), thereby obtaining a double-sided circuit board.

FIGS. 9A to 9D are process cross-sectional views showing a conventional method for manufacturing a multilayer substrate, and show a four-layer substrate as an example.

First, as shown in FIG. 9A, FIG.
To (f), the circuit patterns 11a and 12
b), and aramid-epoxy sheets 1a and 1b in which through holes are filled with conductive paste 2 (the sheets 1a and 1b are manufactured by steps (a) to (d) in FIG. 8). Is prepared.

Then, the metal foil 4, the aramid-epoxy sheet 1b, the double-sided circuit board 10, the prepreg sheet 1a, and the metal foil 4 are stacked on the positioning pins 46 provided on the lamination mold 47 in this order through the positioning holes 3.

Next, as shown in FIG.
By heating and pressing with a hot press with 8 placed on it,
As shown in FIG. 9C, aramid-epoxy sheet 1
The thicknesses of a and 1b are compressed (t2 = about 100 μm), the double-sided circuit board 10 and the metal foil 4 are bonded, and the circuit patterns 11a and 11b are connected to the metal foil 4 and the inner via hole by the conductive paste 2. .

Then, as shown in FIG. 9D, the metal foils 4 on both sides are selectively etched to form the circuit patterns 12a, 1a.
By forming 2b, a four-layer substrate is obtained.

Generally, the heating and pressurizing step by a hot press is a batch type, and the curing time of a prepreg sheet used for a circuit board is as long as 1 to 3 hours. Therefore, in order to increase the productivity, it is important to increase the number of processes of the circuit board in one press and to improve the workability before and after the press.

[0019]

However, the above-mentioned conventional method for manufacturing a multilayer board requires a mold provided with positioning pins. First, a circuit board having a small clearance on the positioning pins of the mold is required. And the positioning and lamination by passing through the positioning holes of the prepreg sheet, the resin component of the prepreg sheet melted at the time of heating and pressing adheres to the positioning pins, making it difficult to remove the circuit board, lowering the work efficiency, and There has been a problem that the positioning pins are deformed and the lamination accuracy is reduced.

Secondly, in order to ensure the accuracy of the positioning pins, for example, a 300 mm square mold having a plate thickness of about 10 mm is used. There are problems that the number of molds is reduced and the weight of the mold is about 15 kg, so that workability is reduced and it is difficult to increase the substrate size.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a multilayer substrate for realizing a multilayer substrate having high lamination accuracy and excellent productivity.

[0022]

In order to achieve the above-mentioned object, a method of manufacturing a multilayer board according to the present invention comprises positioning a circuit board and a prepreg sheet so as to overlap each other, and partially heating an arbitrary portion of the prepreg sheet. After curing and bonding and fixing to a circuit board, a metal foil is attached to both sides of the circuit board, and heated and pressed by a hot press to obtain a multilayer board. Here, the partially cured prepreg
Any part of the sheet is located on the circuit pattern of the circuit board.
This is a position corresponding to the portion from which the metal foil has been removed.

[0023]

[0024]

[0025]

According to the present invention constructed as described above, an arbitrary portion of the positioned prepreg sheet is heated and pressed to be adhered and fixed to a circuit board. Eliminating problems such as peculiar poor detachability of the circuit board and deformation of the positioning pin are eliminated. In addition, the number of processes of the circuit board corresponding to the thickness of the mold increases, the productivity is improved, and the weight can be reduced, so that it is easy to cope with an increase in the board size. In addition, due to partial curing of the prepreg sheet, displacement of the metal foil, circuit board, and prepreg sheet during hot pressing can be prevented, and a high-precision multilayer board can be realized. In particular, if metal foil remains at the bonding site,
Heating conditions fluctuate because the heat capacity changes depending on the remaining amount
However, in the present invention, it is necessary to remove the metal foil at the bonding site.
To ensure stable bonding under certain bonding conditions.
You.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a multilayer substrate according to an embodiment of the present invention will be described below.

(Example 1) The method of manufacturing a double-sided circuit board serving as a base of a multilayer board is the same as that of the conventional example, and the description is omitted here.

FIGS. 1A to 1F are sectional views showing the steps of a method for manufacturing a multilayer substrate according to a first embodiment of the present invention, and show a four-layer substrate as an example.

In FIG. 1, 1a and 1b are 250 mm square,
An aramid-epoxy sheet (prepreg sheet) made of a composite material in which a thermosetting epoxy resin is impregnated into a non-woven aromatic polyamide fiber having a thickness of about 150 μm, and a conductive paste 2 is filled in a through hole processed by a laser or the like. ing.

Numeral 10 designates a double-sided circuit board having a size of 250 mm square and a thickness of about 170 μm.
a and 11b are electrically connected by a conductive paste 2 filled in a through hole provided at a predetermined position. The circuit patterns 11a and 11b of the double-sided circuit board 10 are shown in FIG.
The metal foil 4 has been removed as shown in FIGS.

The conductive paste used at this time was an Ag powder having an average particle size of 2 μm as a conductive filler, and a thermosetting epoxy resin (solvent-free type) as a resin.
As the curing agent, acid anhydride-based curing agents were sufficiently kneaded with three rolls so as to be 85% by weight, 12.5% by weight, and 2.5% by weight, respectively.

The aramid-epoxy sheets 1a and 1b and the double-sided circuit board 10 are provided with two positioning holes 3 of φ3 mm at predetermined positions at a pitch of 180 mm.

Reference numeral 5 denotes a heater chip having a tip of φ5 mm. Reference numeral 7 denotes a positioning pin 6 having a diameter of 2.97 mm.
It is a positioning plate of 200 mm square arranged at a pitch.

The positioning plate 7 is provided with a recess so that the conductive paste 2 filled in the through holes of the aramid-epoxy sheets 1a and 1b does not adhere. Reference numeral 8 denotes an aramid-epoxy sheet 1a, 1b for a double-sided circuit board 1.
This is a dent at the bonding site when bonding by heating to 0.

First, as shown in FIG. 1A, FIG.
Circuit patterns 11a and 11b manufactured by (f)
And the aramid-epoxy sheets 1a and 1b manufactured in FIGS. 5 (a) to 5 (d).

Then, the aramid-epoxy sheet 1b, the double-sided circuit board 10, and the aramid-epoxy sheet 1a are passed through the positioning holes 3 on the positioning pins 6 provided on the positioning plate 7 in this order. At this time, the four sides of the aramid-epoxy sheets 1a and 1b and the double-sided circuit board 10 protrude from the positioning plate 7 by 25 mm.

Next, as shown in FIG. 1B, at predetermined positions of the aramid-epoxy sheets 1a and 1b sandwiching the double-sided circuit board 10 protruding from the positioning plate 7, the upper and lower ends provided with a φ5 mm 300-350 ° C
The heater chip 6 heated to about 500 g applies a pressure of about 500 g to 10
For 2 seconds, the resin components of the aramid-epoxy sheets 1a and 1b are cured and adhered to the double-sided circuit board 10.

In order to maintain the positioning accuracy at the time of lamination, a minimum of two bonding points are required. In this embodiment, four bonding points and four intermediate points are used.

When the heater chip 6 is separated from the aramid-epoxy sheets 1a and 1b, a recess 8 of about 50 μm is formed at the bonding site.

Although the tip shape of the heater chip 5 is circular here, it may be rectangular or elliptical, and is not particularly limited.

Here, the circuit patterns 11a and 11b are obtained by removing the metal foil 4 at the bonding portion of the double-sided circuit board 10. However, when the metal foil 4 remains at the bonding portion of the double-sided circuit board 10, the remaining amount depends on the remaining amount. Since the heat capacity changes, the heating conditions change.

For example, if it remains on the entire surface, a time of 20 seconds or more is required even under the above heating conditions. In other words, the heating condition is set according to the remaining amount of the metal foil 4 at the bonding site. However, by removing all the metal foil 4 at the bonding site, stable bonding can be performed under certain bonding conditions.

Investigation of the relationship between the pressure applied to the heater chip and the adhesive force at this time revealed that, at a pressure of 4 g / cm ² or less, the film was peeled off at the time of transportation after fixing, which was a problem in manufacturing. If the pressure is 5 g / cm ² or more, it can be transported without any problem, and if it is 10 g / cm ² or more, it is more desirable.

Although the temperature varies depending on the resin component of the prepreg sheet to be used, the resin (epoxy resin) generally used for a circuit board has a melting temperature of about 100 ° C., and from the gist of the present invention, the temperature at which curing proceeds. 15
It has been found that there is no problem if the temperature is 0 ° C. or higher. However, desirably from 250 ° C. to 350 ° C. from the viewpoint of the processing time
Is optimal.

Next, as shown in FIG. 1 (c), the double-sided circuit board 10 having the aramid-epoxy sheets 1a and 1b adhered and fixed on both sides is pulled out from the positioning pins 6 of the positioning plate 7, and both sides are metallized. After laminating the foil 4, the whole surface is pressed with a hot press at a pressure of 50 kg / cm ² and a temperature of 200 ° C.
1 hour, the thickness of the aramid-epoxy sheets 1a and 1b is compressed (t2 = about 100 μm) and the two-sided circuit board is pressed by the aramid-epoxy sheets 1a and 1b as shown in FIG. 10 and metal foil 4
Then, the circuit patterns 11a and 11b are connected to the metal foil 4 and the inner via holes by the conductive paste.

Then, as shown in FIG. 1 (f), the metal foil 4 on both sides is selectively etched to form a circuit pattern, thereby obtaining a four-layer substrate.

In order to obtain a multilayer substrate having four or more layers, the same process may be repeated using the multilayer substrate manufactured by the above manufacturing method instead of the double-sided circuit board.

That is, as shown in FIG. 1A, the aramid-epoxy sheet is positioned and overlapped on both sides of the multilayer substrate, and a predetermined position of the aramid-epoxy sheet is partially shifted as shown in FIG. 1B. After heat-curing and bonding, the multilayer board with the aramid-epoxy sheet partially bonded at an arbitrary position is pulled out from the positioning pin of the positioning plate as shown in FIG. 1 (c), and as shown in FIG. 1 (d). The metal foil is bonded to the outermost surface, and heated and pressed by a hot press as shown in FIG. 1 (e) to bond the metal foil and the multilayer board with the aramid-epoxy sheet and to conduct the circuit pattern of the multilayer board and the metal foil. After connecting the inner via holes with a conductive paste, as shown in FIG. 1 (f), a process of processing a metal foil to form a circuit pattern is repeated to obtain a multilayer substrate.

The elimination of the need for a mold in the manufacturing process eliminates the problem of peculiar problems during use of the mold, which is caused by flowing into the molten adhesive positioning hole and is fixed to the positioning pin by adhesion. Now I can work.

The positioning pins in the present embodiment are intended only for positioning. Since the positioning pins are inserted and removed at room temperature, deformation due to removal of the adhesive component of the prepreg sheet caused by melting and fixing is caused. Disappeared, and stable lamination accuracy could be maintained.

Further, by increasing the number of substrates corresponding to the mold thickness (4
It was possible to press (about 4 sheets with a layer substrate), reduce the weight, and easily cope with an increase in substrate size. The lamination accuracy of the completed four-layer substrate of Example 1 is the same as the lamination accuracy (100 μm or less) obtained by using the mold of the conventional example by using the positioning pins for positioning the double-sided circuit board and the prepreg sheet. Was done.

Reference Example 1 FIGS. 3A to 3F are sectional views showing steps of a method for manufacturing a multilayer substrate according to a reference example of the present invention, and show a four-layer substrate as an example.

In FIG. 3, 1a and 1b are 250 mm square,
It is a glass-epoxy sheet (prepreg sheet) made of a composite material in which a thermosetting epoxy resin is impregnated into a glass cloth having a thickness of about 150 μm. Although an unprocessed glass-epoxy sheet is used here, glass-epoxy sheets 1a and 1b in which a conductive paste is filled in through holes processed by a laser or the like may be used.

Reference numeral 10 denotes a double-sided circuit board having a size of 250 mm square and a thickness of about 170 μm, and has a circuit pattern 11 formed on both sides.
a and 11b are electrically connected by a conductive paste 2 filled in a through hole provided at a predetermined position.

Although the double-sided circuit board 10 in which the layers are connected with the conductive paste 2 is used here, the double-sided circuit board 10 (not shown) is formed by drilling holes between the layers and connecting with a metal deposited by electroplating. May be used.

The conductive paste 2 used at this time used a Cu powder having an average particle size of 2 μm as a conductive filler, a thermosetting epoxy resin (solvent-free type) as a resin, and an acid anhydride type as a curing agent. 85 curing agents each
3 wt%, 12.5 wt%, 2.5 wt%
It is kneaded sufficiently with this roll.

Reference numeral 4 denotes a 300 mm square, 35 μm thick metal foil of Cu or the like, and 5 denotes a heater chip having a tip of φ5 mm.

First, as shown in FIG. 3A, the metal foil 4, the glass-epoxy sheet 1b, the double-sided circuit board 10, the glass-epoxy sheet 1a, and the metal foil 4 are positioned on the work stage 51 in the order of outer shape. And stack. At this time,
The four sides of the epoxy sheets 1a and 1b and the double-sided circuit board 10 are protruded from the work stage 51 by 25 mm.

Next, as shown in FIG. 3B, the predetermined positions of the glass-epoxy sheets 1a and 1b holding the double-sided circuit board 10 protruding from the work stage 51 are moved to the metal foil 4 arranged on the outermost surface. Through the tip provided on the top and bottom
5mm heater chip 6 heated to 300-350 ° C
Then, a pressure of about 500 g is applied for 20 seconds to cure the resin components of the glass-epoxy sheets 1a and 1b and adhere to the double-sided circuit board 10.

In this case, at least two bonding points are required to maintain the positioning accuracy at the time of lamination, but in the present embodiment, eight bonding points were used, four corners and four intermediate points.

When the heater chip 6 was separated from the glass-epoxy sheets 1a and 1b, a slight deformation (not shown) occurred in the metal foil 4 at the bonding portion. By bonding the metal foils 4 at the same time, it is possible to reduce the setting time at the time of pressing and prevent dust from adhering to the glass-epoxy sheets 1a and 1b.

In particular, the glass-epoxy sheets 1a, 1b
Is charged with static electricity, so that dust easily adheres and is difficult to remove. Adhesion of the metal foil 4 prevents dust from entering the inside of the glass-epoxy sheets 1a and 1b and makes it easy to remove dust even if it adheres to the metal foil 4.

Next, a glass-epoxy sheet 1 was provided on both sides.
a, the double-sided circuit board 10 on which the
Take out from stage 51 and press with hot press at 50kg
/ Cm ^TwoHeat and press the whole surface at 200 ° C for 1 hour.
As a result, as shown in FIG.
The thickness of the sheets 1a and 1b is compressed (t2 = about 140 μm)
And both sides with glass-epoxy sheets 1a and 1b
The circuit board 10 and the metal foil 4 are bonded.

Next, as shown in FIG. 3D, a through hole 60 is formed at a designated position on the double-sided circuit board 10 by using a drill having a diameter of about 0.4 mm. Then, as shown in FIG. Then, the surface of the substrate is activated, and a metal such as Cu is deposited 64 on the entire surface of the substrate by electroplating.

At this time, the thickness of the deposited metal 64 is 20 μm.
If m or more, the reliability of the through-hole connection can be obtained.

Next, as shown in FIG. 3 (f), the deposited metal and the metal foil 4 on the outermost surface of the multilayered substrate are simultaneously selectively etched to form the circuit patterns 12a and 12b and to form the multilayered substrate. By forming plated through holes 61 for electrically connecting the outermost layer, the outermost layer and the inner layer, a four-layer substrate is obtained.

In order to obtain a multilayer substrate having four or more layers, the same process may be repeated using the multilayer substrate manufactured by the above manufacturing method instead of the double-sided circuit board.

That is, as shown in FIG. 3A, the glass-epoxy sheet and the metal foil are positioned and overlapped on both surfaces of the multilayer board on the work stage, and as shown in FIG. After a predetermined position is partially heated and cured to bond, as shown in FIG. 3C, the entire surface of the substrate is heated and pressed by a hot press, and the metal foil and the multilayer substrate are bonded by a glass-epoxy sheet. As shown in FIG. 3D, through holes are drilled at designated positions on the multilayer substrate, and FIG.
After depositing a metal such as Cu on the entire surface of the multilayer substrate as shown in FIG. 3E, the deposited metal and the metal foil on the outermost surface are simultaneously processed as shown in FIG. multilayer substrate by repeating the step of forming the that Re obtain et <br/>.

Embodiment 2 FIGS. 4A to 4C are cross-sectional views showing a method of manufacturing a multilayer substrate according to a second embodiment of the present invention, and show a four-layer substrate as an example.

In FIG. 4, 1a and 1b are 250 mm square,
An aramid-epoxy sheet (prepreg sheet) made of a composite material in which a thermosetting epoxy resin is impregnated into a non-woven aromatic polyamide fiber having a thickness of about 150 μm, and a conductive paste 2 is filled in a through hole processed by a laser or the like. are doing.

The conductive paste used at this time was a Cu powder having an average particle size of 2 μm as a conductive filler, and a thermosetting epoxy resin (solvent-free type) as a resin.
An acid anhydride-based curing agent was sufficiently kneaded with three rolls so as to be 87.5% by weight, 10% by weight and 2.5% by weight, respectively.

20a, 20b and 20c are 250 mm
A double-sided circuit board having a corner and a thickness of about 170 μm, and circuit patterns 21a and 21b, 22a and 22b formed on both sides,
23a and 23b are electrically connected by a conductive paste 2 filling a through hole provided at a predetermined position.

The aramid-epoxy sheets 1a and 1b and the double-sided circuit boards 20a, 20b and 20c are provided with two φ3 mm positioning holes 3 at a pitch of 180 μm. 5 is a heater chip having a tip of φ5 mm.

First, as shown in FIG. 4A, the work stage 51 is suction-pressed in the order of the double-sided circuit board 20c, the aramid-epoxy sheet 1b, the double-sided circuit board 20b, the aramid-epoxy sheet 1a, and the double-sided circuit board 20a. Plate 7
The circuit patterns 21a and 21b, 22a and 2
Using 2b, 23a and 23b, positioning and overlapping are performed by image recognition or the like.

At this time, the aramid-epoxy sheet 1a,
1b and the four sides 4 of the double-sided circuit boards 20a, 20b, and 20c protrude from the work stage 51 by 25 mm.

Next, as shown in FIG. 4B, the double-sided circuit boards 20a, 20b, 20c and the aramid-epoxy sheets 1a, 1b are applied to the double-sided circuit board 20a by about 20 g / cm by the suction pressure plate 70. Aramid-epoxy sheet 1 protruding from work stage 51 under pressure in step ²
The bonding portions of the double-sided circuit boards 20a and 20c holding the
Approximately 50 with heater chip 6 heated to 300-350 ° C
A pressure of 0 g is applied for 20 seconds to cure the resin components of the aramid-epoxy sheets 1a and 1b,
a, 20b, 20c. As in the case of Example 1, the bonding was performed at four corners and four intermediate points, that is, eight places in total.

By applying pressure with the adsorption pressure plate 70,
Aramid-epoxy sheets 1a, 1b and double-sided circuit board 2
It is possible to improve the close contact with Oa, 20b, and 20c to stabilize the positioning, and to prevent the displacement caused by the melting of the epoxy resin at the time of bonding.

The heater chip 5 is connected to the double-sided circuit board 20a,
When separated from 20c, the bonded portions of double-sided circuit boards 20a and 20c are slightly deformed.

Next, aramid-epoxy sea 1a, 1b
Double-sided circuit boards 20a, 20b, 20 bonded and fixed by
c was taken out from the work stage 51, and the entire surface was heated and pressed at 50 Kg / cm ^{2 at} a temperature of 200 ° C. for 1 hour with a hot press, thereby obtaining the aramid-epoxy sheets 1a and 1b as shown in FIG. Is compressed (t2
= About 100 μm) and aramid-epoxy sheet 1
a and 1b adhere the double-sided circuit boards 20a, 20b and 20c to the metal foil 4, and form a circuit pattern 2 on the double-sided circuit board 20a.
1b and the circuit pattern 22a of the double-sided circuit board 20b, the circuit pattern 22b of the double-sided circuit board 20b and the double-sided circuit board 2
For the circuit pattern 23a of 0c, a six-layer substrate connected to the inner via hole by the conductive paste 2 is obtained.

Here, a six-layer board has been described as an example, but in the case of a board having six or more layers, a double-sided circuit board and a prepreg sheet corresponding to the number of layers are prepared, and the prepreg sheet is formed so that the circuit board becomes the outermost layer. Are positioned and overlapped (FIG. 4 (a)),
After the circuit board and the prepreg sheet are partially bonded at an arbitrary position (FIG. 4B), the entire surface is heated and pressed by a hot press to bond the metal foil and the double-sided circuit board with the prepreg sheet, and the circuit of the multilayer board. The pattern and the metal foil are connected to each other with an inner via hole using a conductive paste, and the metal foil is processed to form a circuit pattern as shown in FIG. In the second embodiment, the same effect as in the first embodiment is obtained.

(Embodiment 3) FIGS. 5A to 5F are process sectional views showing a method of manufacturing a multilayer substrate according to a third embodiment of the present invention, and show a six-layer substrate as an example.

In FIG. 5, 1a, 1b and 1c are 250 m
It is an aramid-epoxy sheet (prepreg sheet) made of a composite material in which a thermosetting epoxy resin is impregnated into a non-woven aromatic polyamide fiber of m square and a thickness of about 150 μm. And a conductive paste 2 made of a thermosetting epoxy resin.

20a and 20b are 250 mm square and about 1 thickness.
70 μm first and second double-sided circuit boards, and circuit patterns 21a and 21b and 22a and 22b formed on both sides are electrically connected by conductive paste 2 filled in through holes provided at predetermined positions. .

Further, an aramid-epoxy sheet 1a,
Φ3 mm for 1b, 1c and double-sided circuit boards 20a, 20b
Of the prepreg sheets 1a, 1b, 1 in the double-sided circuit boards 20a, 20b.
Openings 65a and 65b, through which the heater chip 5 having a tip of 5 mm can pass, are provided at the bonding portion of the layer designated by c using a laser, a drill, a punch, or the like.

The openings 65a and 65b are for sequentially bonding the prepreg sheets 1a, 1b and 1c and the double-sided circuit boards 20a and 20b for each number of layers that can be bonded under a constant heating condition. May be cut out as shown in FIG.

Reference numeral 57 denotes a 200 mm square positioning plate on which φ2.97 mm positioning pins 6 are arranged at a 180 mm pitch.

First, as shown in FIG. 5A, aramid-epoxy sheet 1c, double-sided circuit board 20b, aramid-epoxy sheet 1b, double-sided circuit board 20a, aramid-epoxy sheet are applied to positioning pins 6 provided on positioning plate 7. It overlaps through the positioning hole 3 in order of 1a. At this time, the four sides 4 of the aramid-epoxy sheets 1a, 1b, 1c and the double-sided circuit boards 20a, 20b are
From each other by 25 mm.

Next, as shown in FIG. 5B, the aramid-epoxy sheet 1 protruding from the positioning plate 7.
c and the opening 65b provided in the double-sided circuit board 20b,
After passing through the heater chip 6 heated to 0 to 350 ° C., a pressure of about 500 g is applied to the aramid-epoxy sheets 1a and 1b sandwiching the double-sided circuit board 20a for about 10 seconds to remove the resin components of the aramid-epoxy sheets 1a and 1b. It is cured and bonded to the double-sided circuit board 20a.

Next, as shown in FIG. 5C, the aramid-epoxy sheet 1 protruding from the positioning plate 7.
a into the opening 65a provided in the double-sided circuit board 20a.
After passing through the heater chip 6 heated to 0 to 350 ° C., a pressure of about 500 g is applied to the aramid-epoxy sheets 1b and 1c holding the double-sided circuit board 20b for about 10 seconds to remove the resin components of the aramid-epoxy sheets 1b and 1c. It is cured and adhered to the double-sided circuit board 20b.

Here, aramid-epoxy sheet 1
Although a, 1b, 1c and the double-sided circuit boards 20a, 20b are sequentially bonded for each layer, they may be collectively bonded as shown in the first and second embodiments.

As shown in FIG. 5 (b) and FIG. 5 (c), bonding points were made at four corners and four intermediate points, respectively, as in Example 1, for a total of eight points.

Next, the intermediate aramid-epoxy sheet 1
a, double-sided circuit board 20 bonded and fixed with 1b, 1c
After the a and 20b are removed from the positioning pins 6 of the positioning plate 7, as shown in FIG. 5 (d), a metal foil 4 is attached to the outermost surface, and the entire surface of the substrate is pressed with a pressure of 5 by a hot press.
By heating and pressing at 0 Kg / cm ^{2 at} a temperature of 200 ° C. for 1 hour, the thickness of the aramid-epoxy sheets 1a, 1b, 1c is compressed as shown in FIG. 5 (e) (t2 =
Aramid-epoxy sheet 1 together with about 100 μm)
a, 1b, and 1c bond the double-sided circuit boards 20a, 20b and the metal foil 4, and also between the circuit pattern 21b of the double-sided circuit board 20b and the circuit pattern 22a of the double-sided circuit board 20b and between the circuit pattern 21a of the circuit board 20a and the circuit board 20b. The inner via hole connection is made by the conductive paste 2 between the circuit pattern 22b and the metal foil 4.

Next, as shown in FIG. 5 (f), the metal foils 4 on both sides are selectively etched to form the circuit patterns 23a,
By forming 23b, a six-layer substrate can be obtained collectively.

Here, a six-layer board has been described as an example, but in the case of a board having six or more layers, a double-sided circuit board and a prepreg sheet corresponding to the number of layers are prepared, and the prepreg sheet is positioned so as to be the outermost layer. The double-sided circuit board and the prepreg sheet are sequentially adhered (FIGS. 5 (b) and 5 (c)) for each of the number of layers that can be laminated (FIG. 5 (a)) and can be adhered under a constant heating condition (FIGS. 5 (b) and 5 (c)), and a metal foil is bonded to the outermost surface (FIG. 5D), the entire surface of the substrate is heated and pressed by a hot press as shown in FIG.
The circuit pattern is formed by bonding the metal foil and the multilayer board with an epoxy sheet, connecting the circuit pattern of the multilayer board and the metal foil with inner via holes using a conductive paste, and processing the metal foil as shown in FIG. 5 (f). By doing so, a multilayer substrate can be obtained at once.

(Reference Example) FIGS. 7A to 7D are process cross-sectional views showing a method for manufacturing a multilayer substrate according to a reference example of the present invention , and show a six-layer substrate as an example.

In FIG. 7, 1a, 1b and 1c are 250 m
An aramid-epoxy sheet (prepreg sheet) made of a composite material in which a thermosetting epoxy resin is impregnated into a glass woven fabric with an m-square and a thickness of about 150 μm. The conductive paste 2 made of a mold epoxy resin is filled.

Reference numerals 20a and 20b denote double-sided circuit boards of 250 mm square and a thickness of about 170 μm. Circuit patterns 21a and 21b and 22a and 22b formed on both sides are conductive paste filled in through holes provided at predetermined positions. 2 are electrically connected.

Reference numeral 4 denotes a 300 mm square, 35 μm thick metal foil of Cu or the like, and 5 denotes a heater chip having a tip of φ5 mm.

First, as shown in FIG. 7A, a metal foil 4, an aramid-epoxy sheet 1c, a double-sided circuit board 20b, an aramid-epoxy sheet 1b, a double-sided circuit board 20b, an aramid-epoxy sheet 1a, The metal foil 4 is adsorbed in the order of the metal foil 4 by the adsorption and pressure plate 70.
Is the outer shape, aramid-epoxy sheets 1a, 1b, 1c
And the double-sided circuit boards 20a, 20b
Using the positioning pattern 66 provided in b, positioning is performed by image recognition or the like, and the layers are overlapped.

At this time, the aramid-epoxy sheet 1a,
The four sides 4 of 1b, 1c and the double-sided circuit boards 20a, 20b protrude from the positioning plate 7 by 25 mm.

Next, as shown in FIG.
, A double-sided circuit board 20a with a suction pressure plate 70,
20a and the aramid-epoxy sheets 1a, 1b, and 1c protruding from the work stage 51 in a state where they are pressed at about 20 g / cm ^2.
c and the double-sided circuit boards 20a and 20b are applied from the outermost metal foil 4 to the aramid-epoxy sheets 1a and 1b by applying a pressure of about 500 g for 20 seconds with the heater chip 6 heated to 300 to 350 ° C. The resin component 1c is cured and bonded to the double-sided circuit boards 20a and 20b and the metal foil 4.

As in the case of Example 1, the bonding was performed at four corners and four intermediate points, that is, eight places in total.

By applying pressure with the suction pressure plate 70,
The adhesion between the aramid-epoxy sheets 1a, 1b, 1c and the double-sided circuit boards 20a, 20b is improved to stabilize the positioning, and it is possible to prevent the displacement caused by the melting of the epoxy resin at the time of bonding.

At this time, the suction pressurizing plate 70 for pressurizing
When the conductive paste 2 is filled in the through holes in the outermost aramid-epoxy sheets 1a and 1c, the work stage 51 and the work stage 51
In some cases, the conductive paste 2 may adhere to and come off of the conductive paste 2. Therefore, a structure that avoids the conductive paste 2 filling portion, for example, a concave portion may be provided on a plate surface within a certain range of the conductive paste 2 filling portion.

A flat plate may be used when the conductive paste 2 is not filled or when the conductive paste 2 is filled but the metal foil 4 is on the outermost surface.

When the double-sided circuit boards 20a, 20b are the outermost surfaces, the circuit patterns 21a, 21b, 22a,
A protective material such as an elastic body may be added so as not to damage the 22b. Here, since the metal foil 4 is the outermost surface, the suction pressure plate 70 and the work stage 51 are flat.

Next, the pressure is set to 50 kg / cm by a hot press.
^2. By heating and pressing at 200 ° C for 1 hour,
As shown in FIG. 7C, aramid-epoxy sheet 1
The thicknesses of a, 1b, and 1c are compressed (t2 = about 100 μm).
m) with aramid-epoxy sheets 1a, 1b, 1
c adheres the double-sided circuit boards 20a, 20b and the metal foil 4, and also between the circuit pattern 21b of the double-sided circuit board 20b and the circuit pattern 22a of the double-sided circuit board 20b, between the circuit pattern 21a of the circuit board 20a and the metal foil 4, Substrate 2
An inner via hole connection is made between the circuit pattern 22b of Ob and the metal foil 4 by the conductive paste 2.

Next, as shown in FIG. 7D, the metal foils 4 on both sides are selectively etched to form the circuit patterns 23a,
By forming 23b, a six-layer substrate can be obtained collectively.

Here, a six-layer board has been described as an example, but in the case of a board having six or more layers, a double-sided circuit board and a prepreg sheet corresponding to the number of layers are prepared so that the prepreg sheet is in contact with the outermost metal foil. Position and overlap (FIG. 7 (a)),
The double-sided circuit board and the prepreg sheet are adhered from above the metal foils on both sides (FIG. 7 (b)), and as shown in FIG. After bonding with the double-sided circuit board group and connecting between the circuit patterns of the double-sided circuit board and between the double-sided circuit board and the metal foil with an inner via hole using a conductive paste, FIG.
By processing the metal foil to form a circuit pattern as shown in (d), a multilayer substrate can be obtained collectively .

As described above, according to the present invention, the prepreg sheet is heat-cured before hot pressing and adheres to the double-sided circuit board, and a mold is not required. It is possible to eliminate certain poor removability and deformation of the positioning pin. In addition, it is possible to increase the number of substrates corresponding to the thickness of the mold and to perform pressing, reduce the weight, and easily cope with an increase in the size of the substrate.

Further, by partially curing the prepreg sheet, the displacement of the metal foil, the circuit board and the prepreg sheet during hot pressing can be prevented, and a high-precision multilayer board can be realized.

In the examples, a prepreg sheet (aramid-epoxy sheet) obtained by impregnating a thermosetting resin into a nonwoven fabric mainly composed of an organic material and a woven fabric mainly composed of an inorganic material impregnated with a thermosetting resin are used. A prepreg sheet (glass epoxy sheet) was used, but a thermosetting resin was impregnated in a prepreg sheet in which a cloth mainly composed of an organic material was impregnated with a thermosetting resin or a nonwoven fabric mainly composed of an inorganic material. In addition, although a prepreg sheet was used, the heater was always used as the heating means in the examples, but a pulse heater, an ultrasonic wave,
Similar effects can be obtained by using a laser.

[0113]

As described above, by heating and curing the prepreg sheet before hot pressing and bonding the prepreg sheet to the double-sided circuit board, the need for a mold is eliminated. Eliminates badness, deformation of positioning pins, etc., increases the number of substrates equivalent to the thickness of the mold, reduces weight, and easily handles large substrate sizes. A method for manufacturing a substrate can be provided. In particular, metal foil remains
The heating capacity depends on the remaining amount.
However, in the present invention, the metal foil at the bonding site is removed.
So that it is stable under certain bonding conditions
Can be bonded.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing a method for manufacturing a multilayer substrate according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a circuit pattern of a double-sided circuit board at a prepreg sheet bonding portion in the embodiment.

Sectional views illustrating a method for manufacturing a multilayer substrate definitive in Reference Example of the present invention; FIG.

FIG. 4 is a process sectional view illustrating a method for manufacturing a multilayer substrate according to a second embodiment of the present invention.

FIG. 5 is a process sectional view illustrating a method for manufacturing a multilayer substrate according to a third embodiment of the present invention.

FIG. 6 is a plan view showing the shape of the opening of the bonding portion between the prepreg sheet and the double-sided circuit board in the embodiment.

FIG. 7 is a process sectional view illustrating the method for manufacturing the multilayer substrate in the reference example of the present invention.

FIG. 8 is a process sectional view of a conventional method for manufacturing a double-sided circuit board.

FIG. 9 is a process cross-sectional view illustrating a method for manufacturing a multilayer substrate.

[Explanation of symbols]

1a, 1b Aramid-epoxy sheet (prepreg sheet) 2 Conductive paste 3 Positioning hole 4 Metal foil 5 Heater chip 6 Positioning pin 7 Positioning plate 8 Adhesion site dent 10 Double-sided circuit board 11a, 11b, 12a, 12b Circuit pattern

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Sadao Mitamura 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Toshihiro Nishii 1006 Kadoma, Kazuma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Takahiko Iwaki 1006 Odaka, Kazuma, Kadoma, Osaka Pref. Hideyuki Ishimaru 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture (72) Inside Matsushita Electric Industrial Co., Ltd. JP-A-63-56995 (JP, A) JP-A-2-241091 (JP, A) JP-A-60-178694 (JP, A) -507388 (JP, A)

Claims (3)

(57) [Claims] 1. A step of positioning and sandwiching a prepreg sheet on both sides of a circuit board having a circuit pattern of at least two layers, and partially heating and pressurizing an arbitrary portion of the prepreg sheet sandwiched on both sides to cure. Bonding the metal foil to the circuit board, and further arranging a metal foil on the outermost surface of the two-sided prepreg sheet partially bonded and fixed, and heating and pressing the entire surface to cure the prepreg sheet, thereby bonding the metal foil and the circuit. It includes a step of performing bonding of the substrate, a step of forming a circuit pattern on both sides by processing the metal foil, prior to
Any part of the prepreg sheet to be partially cured
The metal foil on the circuit pattern of the circuit board is removed
A method for manufacturing a multilayer substrate, the method comprising: 2. It has a circuit pattern of at least two layers.
Alternately with multiple circuit boards and multiple prepreg sheets
Positioning and stacking, and the positioned circuit board
Partially heat any part of plate group and prepreg sheet group
Pressing and hardening the prepreg sheet to form the circuit board group
And the step of bonding and fixing the prepreg sheet group and
The prepreg sheet is cured by heating and pressing the surface.
And bonding the circuit board group to the circuit board group.
Any part of the prepreg sheet to be cured
In the area where the metal foil on the circuit pattern of the circuit board has been removed
A method for manufacturing a multilayer substrate, wherein the method is a corresponding position . 3. It has a circuit pattern of at least two layers.
Alternately with multiple circuit boards and multiple prepreg sheets
Positioning and stacking, and the positioned circuit board
Partially heat any part of plate group and prepreg sheet group
Pressing and hardening the prepreg sheet to form the circuit board group
And the step of bonding and fixing the prepreg sheet group and
The prepreg sheet is cured by heating and pressing the surface.
And bonding the circuit board group to the circuit board group.
Circuit board group and prepreg
Circuit boards other than the layer to be bonded after stacking multiple sheets
The prepreg sheet has an opening through which heating means can pass.
A method of manufacturing a multilayer substrate, wherein the adhesive layers are sequentially moved and bonded .