JP2768236B2 - 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 multilayer substrate having metal foils on both sides.

[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 such a multi-layer substrate, a connection method for connecting inner circuit holes between a plurality of circuit patterns and a highly reliable connection structure are required.

Hereinafter, a description will be given of a step of bonding a prepreg sheet and a plastic sheet in a conventional method for manufacturing a multilayer substrate.

FIGS. 2A to 2C are cross-sectional views showing a bonding process between a prepreg sheet and a plastic sheet in a conventional method for manufacturing a multilayer substrate.

First, the components in FIGS. 2A to 2C will be described. 1 is 500mm square, thickness 200 ~
A prepreg sheet 1 having a thickness of 300 μm, for example, a base material (hereinafter referred to as an aramid-epoxy sheet) made of a composite material having pores therein, in which a non-woven aromatic polyamide fiber is impregnated with a thermosetting epoxy resin. .

Reference numeral 2 denotes a roll-shaped plastic sheet having a width of 550 mm and a thickness of 10 μm, which is coated on one side with a Si-based release agent. For example, polyethylene terephthalate (hereinafter referred to as a PET sheet) is used.

Reference numeral 6 denotes a cutter used for cutting the PET sheet 2, and reference numeral 7 denotes a 500 mm square, 1 mm thick metal plate such as stainless steel used for bonding by heating and pressing with a hot press.

First, as shown in FIG. 2A, the PET sheet 2 is cut by a cutter 6 so as to be longer than the length of the aramid-epoxy sheet 1 by 30 to 50 mm. PET
Two sheets 2 are prepared for one aramid-epoxy sheet 1.

Next, as shown in FIG. 2B, the front and back of the aramid-epoxy sheet 1 are placed on a metal plate 7 by a PET sheet 2.
And the metal plate 7 is further overlapped.

Then, as shown in FIG. 2C, the PET sheet 2 is placed on the front and back of the aramid-epoxy sheet 1 by heating and pressing at 100 ° C. and 20 kg / cm ² for 10 minutes.
Are adhered.

Using the aramid-epoxy sheet 1 with the PET sheet 2 adhered to the front and back by the above-described method, a method of manufacturing a two-layer substrate serving as a base for multilayering will be described.

FIGS. 3A to 3F are process sectional views showing a method for manufacturing a two-layer substrate. First, as shown in FIG. 3B, a through hole 13 is formed at a predetermined position of the aramid-epoxy sheet 1 (FIG. 3A) to which the PET sheet 2 is adhered, using a laser processing method or the like.

Next, as shown in FIG.
Is filled with a conductive paste 14. Conductive paste 1
In order to fill the PET sheet 2, the aramid-epoxy sheet 1 having the through holes 13 is placed on a table of a printing machine (not shown).
Is printed from above, and the conductive paste 14 is
Is emphasized.

At this time, the PET sheet 2 on the upper surface plays a role of a print mask and a role of preventing contamination of the surface of the aramid-epoxy sheet 1.

Next, as shown in FIG.
The PET sheet 2 is peeled off from both sides of the epoxy sheet 1.

Next, as shown in FIG.
A metal foil 15 such as a copper foil is attached to both surfaces of the epoxy sheet 1.

By heating and pressurizing in this state, FIG.
As shown in (f), the thickness of the aramid-epoxy sheet 1 is compressed (t1> t2), and the aramid-epoxy sheet 1 and the metal foil 5 are bonded. Then, the metal foil 5 on the front and back is selectively etched to form a circuit pattern, and a two-layer substrate is obtained.

Next, FIGS. 4A to 4E are process cross-sectional views showing a conventional method of manufacturing a multilayer substrate, and show a four-layer substrate as an example.

First, as shown in FIGS. 4A and 4B, the first two-layer substrate 21 on which the first circuit pattern 16 is formed is formed by the steps shown in FIGS. 3A to 3F. The second substrate 22 on which the second circuit pattern 17 is formed is manufactured. At the same time, the intermediate connector 23 shown in FIG.
To (d).

Next, as shown in FIG. 4D, an intermediate connector 23 is stacked on the first two-layer substrate 21, and a second two-layer substrate 22 is stacked thereon.

Then, as shown in FIG. 4E, the first two-layer substrate 21 and the second two-layer substrate 22 are bonded by an intermediate connector 23 by applying heat and pressure, and the first circuit pattern 1 is formed.
6 and the second circuit pattern 17 are connected to the inner via hole by the conductive paste 14 to obtain a multilayer substrate.

As described above, in the manufacture of the multilayer substrate, the P-bonded to the front and back of the aramid-epoxy sheet 1 is used.
The ET sheet 2 forms a through hole 13 by laser processing or the like,
It is used as a mask when printing the conductive paste 14, and is peeled off after printing.

Therefore, the aramid-epoxy sheet 1
A PET sheet 2 is uniformly adhered to the surface, and it is necessary that this PET sheet does not peel off during laser processing or printing.

Since the aramid-epoxy sheet 1 is used for bonding between the metal foil 15 and the two-layer substrates 21 and 22 by the subsequent heating and pressing, the flowability of the resin component during the heating and pressing reduces the adhesive force. Depends.

The resin component of the aramid-epoxy sheet 1 is in the B-stage state, and the curing progresses depending on the temperature and time, and the flowability decreases.

For example, an aramid-epoxy sheet having a flowability of 15% is reduced to 10% at 100 ° C. for 10 minutes.

When the flowability of the resin component is reduced, a portion having a weak adhesive force or a hollow portion due to a shortage of resin is generated in a later manufacturing process of the multilayer substrate, which causes a great problem in quality. It is important to shorten the heat history at the time of bonding the PET sheet 2 to secure the flowability of the resin component of the aramid-epoxy sheet 1.

[0029]

However, in the above-mentioned conventional structure, since the entire surface of the prepreg sheet is heated and pressed simultaneously, air pockets between the plastic sheet and the prepreg sheet cannot be removed, and wrinkles and adhesion of the plastic sheet to the prepreg sheet cannot be achieved. Liability is likely to occur. If the adhesion is insufficient and a gap is generated between the plastic sheet and the prepreg sheet, the conductive paste enters the gap when filling the conductive paste after opening the through-hole, and the diameter of the through-hole becomes apparently large, resulting in a finer structure. And short-circuits with adjacent patterns and adjacent through-holes.

Further, the heat history at the time of bonding is long, and the flowability of the resin component of the plastic sheet is reduced, resulting in a shortage of resin in the production process of the multilayer substrate, which has been a major problem in quality.

In addition, the conventional manufacturing method has a problem in terms of productivity because the cutting of the plastic sheet, the superposition with the prepreg sheet, and the heating and pressurization by the hot press are discontinuous.

The present invention solves the above-mentioned conventional problems, and provides a method of manufacturing a multilayer substrate for realizing a high-performance, high-quality multilayer substrate by stably bonding a prepreg and a plastic sheet in a short time. It is intended to do so.

[0033]

In order to achieve the above object, a method of manufacturing a multilayer substrate according to the present invention comprises applying a release agent to one side of the prepreg sheet in a bonding step between the plastic sheet and the prepreg sheet. It is arranged in such a manner that it is held between the release agent application surfaces of the plastic sheets, and is passed through a rotating roll capable of applying a predetermined temperature and pressure to soften the resin component of the prepreg sheet and pressurize and adhere. .

[0034]

According to the present invention constructed as described above, the prepreg sheet and the plastic sheet are bonded while the air pool is pushed out by sequentially heating and pressing uniformly by the rotating rolls. At the same time, the adhesion is stable, and the short circuit between the adjacent pattern and the adjacent through hole, which is generated when the conductive paste after drilling the through hole enters the through hole and enters the gap between the prepreg sheet and the plastic sheet, can be prevented.

Further, since the bonding with the rotating rolls is sequentially completed in a few seconds by line contact, there is no decrease in the flowability of the resin component of the prepreg sheet after bonding, and it is possible to eliminate shortage of resin in the production process of the multilayer substrate. it can. In addition, it is possible to continuously adhere with a rotating roll, so that productivity can be improved.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a description will be given of a bonding step between a prepreg sheet and a plastic sheet in one embodiment of a method for manufacturing a multilayer substrate according to the present invention.

FIG. 1 is a cross-sectional view of a roll structure of a laminator used for bonding a prepreg sheet and a plastic sheet and a bonding process.

1 is, for example, a 500 mm square formed of a composite material having non-woven aromatic polyamide fibers impregnated with a thermosetting epoxy resin and having pores therein, and having a thickness of 20 mm.
An aramid-epoxy sheet (prepreg sheet) having a thickness of 0 to 300 μm is provided. Reference numeral 2 denotes a roll-shaped PET sheet (plastic sheet) having a width of 500 mm and a thickness of 10 μm coated with a Si-based release agent on one side.

The rolled PET sheet 2 is attached to the PET sheet mounting rolls disposed above and below the laminator.
Are attached in such a manner that the aramid-epoxy sheet 1 is sandwiched on the release agent application surface.

In the advancing direction, the preheating roll 3 and the heating roll 4 are arranged vertically in this order. The preheating roll 3 and the heating roll 4 are rolls having a diameter of 80 mm and a length of 700 mm, each of which is formed by lining a heat-resistant silicone rubber having a thickness of 5 mm and a rubber hardness of 70 on a metal roll having a diameter of 70 mm. ° C and the surface temperature of the heating roll 4 are controlled at 120 ° C, and the preheating roll 3 and the heating roll 4 are pressurized with an air pressure of ² kg / cm ² . The feed speed of the roll is 2 m / min.

In the initial operation of this apparatus, first, only the PET sheets 2 arranged vertically are inserted between the preheating roller 3 and the pressure roller 4 in a state where they are overlapped with each other. At this time, the PET sheets 2 are overlapped so that the release agent application surfaces are in contact with each other.

Next, the aramid-epoxy sheet 1 is sandwiched between the rotating portions of the preheating roll 3 while the leading end of the superposed PET sheet 2 has passed through the heating roll 4.
It is inserted between the sheets 2. The injected aramid-epoxy sheet 1 moves together with the PET sheet 2 and passes through the heating roll 4, but the heating of the roller softens the resin component of the aramid-epoxy sheet 4, and further presses the roller to press the PET sheet 2. And adhesion is performed.

Second and subsequent aramid-epoxy sheets 1
As for the adhesion between the PET sheet and the aramid-epoxy sheet 1, the PE sandwiched between the rotating parts of the preheating roll 3 was used.
If the PET sheets 2 are sequentially inserted between the T sheets 2, they can be continuously bonded to the PET sheet, and the cutting of the PET sheet 2 can be performed as soon as the bonding is completed.

In the bonding step of this embodiment, since heating and pressurization are performed sequentially and uniformly by a rotating roll, the PET sheet 2
And the aramid-epoxy sheet 1 is reliably pressed, and the air between the two is reliably removed, so that no air pockets or wrinkles are generated, and the extremely excellent adhesion is stabilized. Can be realized.

Although the sheet was actually adhered to 100 aramid-epoxy sheets 1, no wrinkles or variations in adhesion of the PET sheets 2 were found in all the sheets.

In addition, the flowability of the resin component of the aramid-epoxy sheet 1, which is a major problem in the method of manufacturing a multilayer substrate, is as follows:
Since the bonding with the rotating roll was completed sequentially in several seconds by line contact, the heat history was short, and it was confirmed that there was no change of 15% before and after bonding.

In addition, productivity was able to continuously bond the 500 mm square aramid-epoxy sheet 1 at 4 sheets / min even at the speed of 2 m / min of the embodiment, and the productivity was dramatically improved.

Next, the PET sheet 2 is prepared by the method described above.
A four-layer board was manufactured using the aramid-epoxy sheet 1 with which was adhered on both sides. The method for manufacturing a two-layer substrate and the method for manufacturing a multilayer substrate, which are the bases for the subsequent multi-layering, are all the same as those in the conventional example, and thus description thereof is omitted here.

The four-layer substrate thus obtained is used as a mask for printing the conductive paste in the through holes.
Since the T sheet 2 is uniformly adhered to the aramid-epoxy sheet 1 without wrinkles due to residual air, the adjacent conductive paste is contained in the through-hole and enters the gap between the aramid-epoxy sheet 1 and the PET sheet 2 to form an adjacent portion. The occurrence of the short circuit phenomenon between the pattern and the adjacent through-hole was completely eliminated.

Further, since the flowability of the resin component of the aramid-epoxy sheet 1 was not reduced, a high quality multilayer substrate was obtained without resin shortage during the production of the multilayer substrate.

As described above, according to the above embodiment, in the step of bonding the plastic sheet to the front and back surfaces of the prepreg sheet, by applying heat and pressure by the rotating roll to bond, the wrinkles due to the residual air can be eliminated, and Adhesion is stable, and a short circuit between an adjacent pattern and an adjacent through hole, which is generated when the conductive paste after the through hole is inserted into the through hole and enters the gap between the prepreg and the plastic sheet, can be prevented.

Further, since the bonding with the rotating roll is completed in a few seconds by line contact, there is no decrease in the flowability of the resin component of the prepreg sheet after bonding, and there is no shortage of resin in the production process of the multilayer substrate, and high quality is achieved. A multilayer substrate can be realized. In addition, continuous bonding becomes possible, and productivity can be improved.

Although a prepreg sheet in which a non-woven fabric is impregnated with a thermosetting resin is used here, similar results can be obtained by using a prepreg sheet in which a woven fabric is impregnated with a thermosetting resin.

Although a prepreg sheet processed into a predetermined shape is used here, a similar result is obtained by using a continuous prepreg sheet.

[0055]

As described above, according to the present invention, a highly reliable multilayer substrate can be manufactured with excellent mass productivity.
Industrially superior effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a bonding step between a pre-breg sheet and a plastic sheet in one embodiment of a method for manufacturing a multilayer board of the present invention.

FIG. 2 is a cross-sectional view showing a bonding step of a conventional pre-breg sheet and a plastic sheet.

FIG. 3 is a process sectional view showing a conventional method for manufacturing a two-layer substrate.

FIG. 4 is a process sectional view showing a method for manufacturing a conventional four-layer substrate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1, 11 Aramid-epoxy sheet (prepreg sheet) 2, 12 PET sheet (prestic sheet) 3 Preheating roll 4 Heating roll 5 PET sheet mounting roll 6 Cutter 7 Metal plate 13 Through hole 14 Conductive paste 15 Metal foil 16 First Circuit pattern 17 second circuit pattern 21 first two-layer substrate 22 second two-layer substrate 23 intermediate connector

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-155793 (JP, A) JP-A-63-59517 (JP, A) JP-A-1-225395 (JP, A) JP-A-4- 37537 (JP, A) JP-A-2-84318 (JP, A) JP-A-6-20035 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05K 3 / 00,3 / 40,3 / 42,3 / 46 B29C 65/00-65/82

Claims (3)

(57) [Claims] 1. A through hole is made in a compressible prepreg sheet having a releasable plastic sheet on the front and back, a conductive paste is filled in the hole, and the plastic is peeled off. A method of manufacturing a multi-layer substrate in which a metal material is heated and pressure-contacted to the front and back sides and a plurality of circuit materials formed by etching the metal material are laminated, and in a bonding step between the plastic sheet and the prepreg sheet, the metal sheet is processed into a predetermined shape. Alternatively, the prepreg sheet having continuous compressibility is arranged so that the front and back sides of the prepreg sheet are sandwiched by the release agent application surface of a plastic sheet having one side coated with a release agent, and the rotation is performed at a predetermined temperature and pressure. A method for producing a multilayer substrate in which a resin component of a prepreg sheet is softened by passing through a roll, and pressure is applied to bond the resin component. 2. The method according to claim 1, wherein the compressible prepreg sheet is a composite material of a nonwoven fabric and a thermosetting resin and is porous. 3. The method according to claim 1, wherein the prepreg sheet having compressibility is a composite material of a woven fabric and a thermosetting resin.