JP3145079B2 - Method and apparatus for manufacturing multilayer printed circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a printed circuit board, a multilayer printed circuit board obtained by laminating the substrates, a method for manufacturing a multilayer printed circuit board, and a manufacturing apparatus.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a multilayer printed circuit board, a prepreg material obtained by impregnating glass fiber with an epoxy resin and semi-curing is laminated on an inner layer core substrate having circuit patterns on both sides, and furthermore, "copper-clad" A method has been adopted in which a material for an outer layer called a “laminate” is overlapped and subjected to collective press molding. However, in recent years, higher density printed circuit boards,
As densification progresses and the number of laminations increases to 20 layers and 40 layers, problems such as pattern alignment accuracy of each layer, substrate thickness, and weight have arisen.

Therefore, a method has been developed in which a laminated circuit material called "copper foil with resin" is adhesively polymerized one by one on an inner core substrate located at the center as a core material, and is called a build-up molding method. Has been put to practical use. In any of the above methods, it is desired to reduce the overall thickness after lamination, so that the thickness of the resin insulating layer between circuit layers is made as thin as possible (about 60 microns) and the uniformity of the thickness is ensured. A great deal of effort has been put into doing this.

(1) Problems of the prior art First, a description will be given of the collective press molding method and the accompanying problems.
Conventionally, there are a pin laminating method and a mass laminating method as a batch press molding method for a multilayer printed circuit board. Here, problems with the pin lamination method will be described. 13 (a) and 13 (b) In this method, a prepreg material 13 is prepared by impregnating glass fiber with an epoxy resin and semi-curing an inner layer plate 11 having a copper foil 12 on which a circuit pattern is printed in advance. ,
Further, a copper foil 15 for an outer layer is overlaid, they are laminated via a stainless steel plate 17, and thermocompression-bonded at a time by a hot press 19 to form a product 10. After that, a through hole is formed, and interlayer connection is made by a connection hole called a plated via hole, and an outer layer circuit is formed by etching.

[0005] In the pin laminating method or the mass laminating method as a batch press molding method, the material and the number of prepreg materials 13 to be used are determined based on the required thickness of the insulating layer and the amount of resin and resin flow. , The weaving of the glass fiber, the residual ratio of the copper foil of the inner layer circuit pattern, and the like. Then, the schedule of the temperature and the pressure in the thermocompression molding is set according to the characteristics of the prepreg material 13 as shown in FIG. At this time, if the pressure rise is too fast with respect to the temperature rise, the resin flow becomes excessive, and the thickness of the insulating layer between the layers becomes thinner or non-uniform than the specified value, and if too slow, voids (air Contamination) occurs. Conventionally, the reduction and unevenness of the thickness of the resin layer had an adverse effect only on the insulation characteristics, but this problem has been solved by providing a margin in the thickness of the resin (insulation) layer.

However, in recent years, with the increase in the processing speed of electronic equipment, it has become strictly required to control the impedance characteristics of circuit patterns, and the thickness of the insulating layer, which is one of the factors that determine the impedance characteristics, has been increasing. Accuracy control of the accuracy has been emphasized. Since the thickness of the insulating layer to be attached is greatly affected by the residual ratio of the copper foil when the inner layer circuit pattern is formed, there is no means for accurately controlling the thickness of the insulating layer in the above-described pin laminating method. This is the same in the mass lamination method. Thus, management of the thickness of the insulating layer is a problem in the batch press molding method.

Next, problems in the method of manufacturing a multilayer printed circuit board by the build-up method will be described. There are several manufacturing methods in the build-up molding method, but here, a typical manufacturing method called an additive method is shown in FIG.
5 and FIG. As for another typical production method, which is called a subtraction method, a schematic explanation is omitted, and illustration is omitted.

First step: see (a) A core board material 20 called a copper-clad laminate, which is the center of a multilayer printed board, is shown. The core substrate material 20 is a laminated plate 21 in which a glass fiber cloth impregnated with an epoxy resin is laminated.
A copper foil 23 for forming a circuit pattern is stretched on both sides of the substrate and cured. The general thickness of the copper-clad laminate (core substrate material) 20 is 0.4 to 0.8 mm.・ Second step: see (b) Inner for circuit connection on the front and back surfaces of core substrate material 20
Drill a hole 25 in the via hole. The size of the hole 25 is usually 0.3 mm in diameter, and the density is 5,000 to 10,000.
/ M ² . Third step: see (c) The entire core substrate material 20 is plated, and the inner cylindrical surface of the circuit connection hole 25 drilled in the second step is plated 230 to form an inner via hole 250. -4th process ... (d) The circuit pattern 24 is formed by etching the surface of the laminated board 20. This is called a core substrate 30.

Fifth step: Refer to (e) The inner via hole 250 of the core substrate 30 and the groove of the circuit pattern 24 are filled with resin (resin 31, resin 3).
3) A resin coating is applied to the entire surface and cured by heating. After curing, the surface is sanded and smoothed. In this case, a liquid thermosetting epoxy resin having a high viscosity is used as the resin. This resin coating is performed in the next step to ensure the planarity of the surface of the insulating (resin) layer and to eliminate the presence of air called voids. If the plane accuracy of the surface of the insulating layer is poor, exposure printing for forming the next circuit pattern cannot be performed correctly. Also, if air remains,
This layer needs to be carefully performed because the layers are peeled off when subjected to a thermal shock or the insulation is deteriorated at a high temperature due to moisture absorption. Therefore, the CMP (Chemical Mechanical) is required.
al Polishing) and the like, and consumes a lot of costs. The filling and smoothing of the holes and the circuit pattern are the first problems of the build-up molding method.

Sixth step: see (f) Insulating layer material 35 called copper foil 352 with resin 351
On the upper and lower surfaces of the core substrate 30 at the same time, and are bonded by heating and pressing. The resin 351 used for the copper foil 352 with the resin 351 is a resin mixed with a thermosetting epoxy resin or a filler having a molecular structure that causes less resin flow during melting. The pressing pressure in the heating / pressing process is strictly controlled. However, since the upper and lower surfaces of the core substrate 30 are simultaneously pressed, even if the pressing pressure on the upper and lower surfaces is the same, the insulation is performed by the ratio of the remaining copper foil and the like. The amount of resin protruding from the layer material 35 was different, and the thicknesses of the upper and lower insulating layers were different, and the planar thickness of the insulating layer was uneven. The reason for using a resin with a small resin flow for the resin layer 351 is to ensure a uniform thickness of the insulating layer by minimizing a decrease in the thickness. However, the resin with a low (poor) resin flow could not completely fill the sharp grooves or holes, causing voids. Also, as in the case of the batch press molding method, the thickness of the insulating layer is greatly affected by the residual ratio of the copper foil during the formation of the circuit pattern, so the thickness of the insulating layer is controlled even when the resin flow is changed. It is impossible. Ensuring a uniform thickness of the insulating layer is the second problem of the build-up molding method.

After the sixth step, a production method (additive method,
The process changes depending on the subtract method. Additive method (a method in which the copper foil adhered in the sixth step is once peeled off and a circuit pattern is formed by plating on the peeled surface) ・ See the seventh step (g) Copper foil pasted together with resin 351 (insulating layer) 352 is removed by etching. The reason for peeling the copper foil 352 is that the heat is dispersed by the copper foil, so that it is not possible to form a hole with a laser, and that the fine irregularities formed on the surface of the copper foil 352 are transferred to the surface of the resin 351 and This is for improving the fixation of the copper plating circuit pattern performed in the step. The third problem of the build-up molding method is an operation, time, and cost for removing the adhered copper foil by etching. -Eighth step: see (h) The inner via hole for interlayer connection is drilled by laser with a laser. -Ninth step: Refer to (i) After the circuit pattern is printed, the circuit 40 is formed by copper plating (the reason being called an additive method).
The inner cylindrical surface of the hole is also plated to form the inner via hole 41. In order to perform this process accurately, planar accuracy of the surface is required. For this reason, filling and sanding in the fifth step are carefully performed. The fifth and subsequent steps are repeated to form a large number of laminated circuits. 16 (i), a first layer circuit 40, a second layer circuit 43, a third layer circuit 45, and a fourth layer circuit 47 are formed.

Subtract method (a method of printing a circuit pattern on a copper foil adhered in the sixth step and removing an excess portion of the copper foil by etching to form a circuit pattern) In this manufacturing method, the heat conduction of the copper foil is reduced. Since the inner via hole for interlayer connection cannot be drilled with a laser because of its high cost, a method of drilling with a laser after removing the copper foil in a portion to be a hole in advance by etching has been adopted. Other than this circuit forming step, the process is similar to the additive method. Conventionally, both the additive method and the subtraction method have been the fifth in the manufacturing method of build-up multilayer printed circuit boards.
Attempts have been made to omit the step of filling the holes and dents of the resin in the process.

Here, a subtraction method in a case where filling of holes and recesses with resin is omitted will be described with reference to FIG. (1) A copper foil 352 provided with a resin 351 on the upper and lower surfaces of the core substrate 30 on which the inner layer circuit pattern is formed is polymerized. (2) Compression is performed by the press hot plate 19. The resin 351 polymerized on the core base material 30 melts and fills the inner layer circuit pattern grooves and via holes. If the upper side melts faster in time, the resin 351 polymerizing on the upper surface of the substrate 30 fills the inner layer circuit pattern groove, and at the same time, the via hole as shown by the arrow as compared with the resin 351 polymerizing on the lower surface. Large amount flows into 250. The thickness S1 of the resin layer 351 on the upper side of the core substrate 30 is determined by the difference in the inflow amount.
And the thickness dimension S2 of the lower resin layer 351 (the dimension S1
> Dimension S2) results. If the upper and lower resins melt at the same time, the air collected in the via hole 250 remains as it is. Further, the resin 351 contracts at the stage of thermosetting, and a dent 353 is generated on the surface of the copper foil 352. Also,
Since a resin having a characteristic of a small resin flow is used to secure the thickness of the insulating layer, air 354 remains in the resin layer.

As described above, when the step of filling the holes and dents on the base material surface with the resin is omitted, the conventional “copper foil with resin” can be obtained.
When the resin layer is thin, even if a resin with a small resin flow is used, the rigidity will decrease when it is melted. Irregularities were formed on the surface, the plane accuracy of the copper foil surface could not be obtained, and printing in the next step was inaccurate. The electrical and mechanical qualities of the product could not be ensured, for example, the air in the resin layer could not be completely eliminated, or the thickness of the insulating (resin) layer on the front and back surfaces differed. In particular, unevenness in the thickness of the insulating layer polymerized on the front and back surfaces of the base material adversely affects the impedance characteristics of the circuit, and has been a serious problem in recent years.

[0015]

The problem to be solved by the present invention is to secure an insulating layer having a uniform thickness on a multilayer printed circuit board, to remove residual air from the insulating layer, and to arrange a circuit for a conductor layer. The purpose is to ensure the plane accuracy of the surface and to facilitate the peeling process of the adhered copper foil.

[0016]

DISCLOSURE OF THE INVENTION The multilayer print base of the present invention
The board is made by laminating a printing substrate around the core substrate
It is composed.

[0017] The printing substrate has a complete thickness with a specified layer thickness.
A first insulating layer made of a cured resin and a semi-cured state
A second insulating layer made of resin, wherein the second insulating layer
Grooves and via holes in the conductor layer of another substrate
And an adhesive between the base material and the base material.

Further, by arranging an ultrafine synthetic fiber cloth between the insulating layer and the conductor layer, or by blending fibers such as aramid fibers in the resin material, rigidity against the pressing force is imparted. The completely cured first resin layer has a thickness required from the impedance characteristics and the insulating characteristics of the substrate and is completely cured, so that the first resin layer withstands heating and pressing pressure and secures a thickness. In addition, the semi-cured second insulating layer is heated by selecting a resin with good (large) resin flow,
After melting and filling the via holes and circuit grooves, excess resin flows out of the four sides by the pressurized pressure, and the fully cured resin layer secures the thickness of the insulating layer.

The method for manufacturing a multilayer printed board according to the present invention comprises:
First made of fully cured resin centering on the core substrate
Copper foil with an insulating layer consisting of an insulating layer and a second insulating layer made of a semi-cured resin, with the second insulating layer facing the conductor layer
A laminating step of simultaneously laminating the upper and lower surfaces of the substrate in a state where
A first step of setting the laminated material to a temperature at which the resin of the second insulating layer melts, and a second step of setting a temperature at which the resin of the molten second insulating layer hardens. And a heating and pressurizing step of heating and pressurizing.
Then, in the heating-pressurizing step is disposed on the upper surface of the substrate
It was in the insulating layer circuit groove of the molten resin conductive layer of the second insulating layer which is melted in a first step, filling the via holes
I do. At that time, it is placed on the lower surface of the substrate to be melted with a time difference.
The second insulating layer to be placed must be fused with the upper molten resin.
This exhausts the air remaining in the via hole. So
Then , the molten resin is cured in the second step,
The semiconductor device has a configuration that serves as an adhesive between the first insulating layer and the conductor layer.

[0020] In the manufacture of multilayer printed circuit board, a release fabric formed in the insulating layer, after the release fabric was heated and pressurized to laminate obtained by laminating the outer surface, peeling peeling peeling fabric of the laminate
A structure is provided in which a cloth peeling step is provided and a rough surface (irregularities) for attaching a conductor layer is formed on the surface of the first insulating layer from which the release cloth has been peeled. In this case, by forming the release cloth with an ultrafine fiber cloth, a fine rough surface similar to the rough surface made of the copper foil can be formed, and the adhesion of the plating of the conductor layer becomes good. Further, a configuration is provided in which a time difference is provided between the timing of starting the melting of the resin in the first step of heating / pressing the upper surface of the substrate and the timing of starting the melting of the resin in the first step of heating / pressing the lower surface of the substrate. Thereby, residual air in the hole can be eliminated.

According to the manufacturing apparatus for continuously manufacturing a multilayer printed board of the present invention, there is provided a transporting means for a core substrate, a first insulating layer formed of a completely cured resin disposed in a transporting path of the core substrate, and a semi-cured state. An insulating layer supplying means for supplying an insulating layer comprising a second insulating layer formed of the above resin so that the second insulating layer is laminated to face the core substrate; and a downstream side of the insulating layer supplying means. A first heating and pressurizing means provided at a temperature at which the resin of the second insulating layer is melted, and a temperature at which the molten resin is arranged at a downstream side of the first heating and pressurizing means to be cured. Second heating and pressurizing means. The first heating / pressurizing means and the second heating / pressurizing means are synchronously pressurized and depressurized, and the transport means are the first heating / pressurizing means and the second heating / pressurizing means. It is provided with a configuration that is driven intermittently in accordance with the pressure removal timing of the pressure means. The first heating / pressurizing means melts the resin of the second insulating layer of the insulating layer laminated on the substrate, fills the circuit grooves and via holes of the conductor layer with the molten resin, The pressurizing means cures the molten resin and bonds the first insulating layer to the substrate.

Further, the first heating / pressurizing means includes a heating delaying means, for example, setting a time difference in a heating start timing, arranging a pressurizing plate having a low thermal conductivity, setting a low power supply, and the like. By means, a configuration is provided in which the heating of one side of the substrate transfer path is delayed with respect to the heating of the other side, thereby eliminating the residual air.

[0023]

Embodiments of the present invention will be described with reference to the drawings. Embodiment 1 In this embodiment, a base material for a printed circuit board will be described. ... See FIG. 1. The substrate 9 for the printed circuit board is a glass epoxy prepreg laminated as an insulating material on the upper and lower surfaces of a core substrate (core substrate) made of a double-sided copper-clad laminate, and pasted with copper. This is a laminate that is provided instead of a combination of laminates. The base material 9 is formed by laminating an insulating layer 5 in which a first insulating layer 5A and a second insulating layer 5B are laminated on a copper foil 7.

The first insulating layer 5A constituting the insulating layer 5 is made of a thermosetting resin, for example, an epoxy resin, and is completely cured by heating. The resin layer that has been completely cured has a thickness required according to the impedance characteristics and insulation characteristics of the substrate, and then a copper foil 7 is adhered thereto. Since the first insulating layer 5A is completely cured, the first insulating layer 5A can withstand a pressing pressure and secure a thickness even when heated. Thickness h ₂ of the first insulating layer 5A has a thickness dimension which is required as an insulating layer is required from the impedance characteristics and insulating properties of the substrate. For example, in this embodiment, h ₂ = 1
It is set to 00 μm. This thickness dimension is completely cured with high accuracy.

The second insulating layer 5B is made of a thermosetting resin, for example, the same epoxy resin as the insulating layer 5A, and is in a semi-cured (B stage) state opposite to the surface on which the copper foil 7 is provided on the first insulating layer 5A. Is laminated (coated). The thickness h ₃ of the second insulating layer 5B is set to about 15 [mu] m. Second insulating layer 5B
Is a resin having a melting point of 125 ° C., a property of curing at 180 ° C., and a resin having a molecular structure that flows well when melted. In a state where the resin having such characteristics is semi-cured to the B stage,
The thickness h ₂ are laminated in the order of 15 microns. Second
The amount of resin of the insulating layer 5B is sufficient to fill the via holes and grooves of the core base material to be laminated. For example, the amount of resin for filling a hole (via hole) is, for example, 0.8 m in thickness of the core substrate.
m, a hole with a diameter of 0.3 mm is 10,000 per m ²
In the case where there are a plurality, the required resin amount is 0.56 cc, and the reduction in the thickness of the second insulating layer 5B is 0.56 μm. The amount of resin required to fill the groove 3b depends on the thickness of the panel plating and the residual ratio of the copper foil at the time of forming the circuit pattern. On the average, the amount of resin required is about 8 cc. It becomes about 8 μm in terms of length. Therefore, the second insulating layer 5B having a layer thickness of 15 μm is
It has a sufficient amount of resin to fill the holes and grooves. The thickness h ₁ of the copper foil 7 to be overlaid on the insulating layer 5 is 18 μm. The substrate 9 is overlaid on the core substrate, and heated and pressed by a hot plate to form a multilayer substrate.

As described above, the base material 9 of the present invention comprises the insulating layer 5
The second insulating layer 5B is melted at a temperature of 125 ° C. to be in a liquid state, and flows into and fills via holes of a core substrate to be laminated;
Fill the circuit grooves in the core substrate. Further, the excess molten resin is pushed out and discharged. Next, set the temperature of the hot plate to 18
The temperature is raised to 0 ° C. to cure the resin in the circuit grooves and via holes filled with the second insulating layer melted. Thus, the substrate 9 on which the circuit is laminated via the insulating layer 5
Is formed.

As described above, when the base material 9 is laminated to form a multilayer printed circuit board, the resin filling the holes and filling the grooves is the second insulating layer 5B, which affects the first insulating layer 5A. Nothing. As a result, the first insulating layer 5A in a completely cured state having a high thickness accuracy as the insulating layer remains to form the insulating layer 5, so that the planar accuracy of the copper foil surface can be ensured. In addition, this base material 9 can fill the holes at the time of heating and pressurizing, secure a uniform thickness of the insulating layer, and secure the planar accuracy of the circuit surface.

Next, another embodiment of the substrate will be described. FIG.
Shows an example in which the first insulating layers 50A in the insulating layer 50 are formed in a strip shape at equal intervals. The first insulating layer 50A is made of a completely cured epoxy resin and has a layer thickness of 60 to 80 μm, and a plurality of first insulating layers are arranged in a ridge shape having a constant width. First insulating layer 5
For 0A, a material in which fibers such as aramid fibers are mixed may be used as a reinforcing material. The second insulating layer 50B is made of a semi-cured (B stage) epoxy resin.
And a layer having a thickness of 15 μm is formed. A copper foil 7 having a thickness of 12 to 18 μm is stuck on the first insulating layer 50A. In the insulating layer 50 thus configured, the second insulating layer 50B and the semi-cured resin that fills the gap are melted by heating. At this time, the flow of the molten resin is in the direction of the gap 51.

FIG. 3 shows an example in which the first insulating layer 55A of the insulating layer 55 is formed in a sawtooth shape. First insulating layer 55A
Is formed in a sawtooth shape with a layer thickness of 40 to 60 μm using a completely cured epoxy resin. Also in this case, a material in which fibers such as aramid fibers are mixed may be used as a reinforcing material. The second insulating layer 55B fills the gap between the first insulating layers 55A made of semi-cured (B stage) epoxy resin and forms a layer having a thickness of 15 μm. The copper foil 7 has a thickness of 12 to 18 μm. This insulating layer 55 is also a semi-cured resin in the gap between the first insulating layers 55A,
And the second insulating layer 55B is melted by heating (at a temperature of 125 ° C.) to fill the grooves and via holes, and then heated (at a temperature of 1 ° C.).
(80 ° C.) to form an insulating layer 55 having a specified thickness.

Embodiment 2 In this embodiment, a method of manufacturing a printed circuit board (build-up molding method) using the printed circuit board base material of the present invention will be described. ... See FIGS. 4 and 5 A First Step (see FIG. 5A) A laminated board material (copper-clad laminate) 8 which is the center of a multilayer printed board is shown. The laminated substrate material 8 is provided on both sides of a laminated plate 81 in which a glass fiber cloth impregnated with an epoxy resin is laminated.
A copper foil 82 for forming a circuit pattern is stretched and cured. The general thickness of the copper-clad laminate (laminated substrate material) 8 is 0.4 to
0.8 mm. B: Second step: see (b) A hole 83 of an inner via hole for circuit connection on the front and back surfaces of the laminated substrate material 8 is formed. Drilling is performed with a drill. Hole size is 0.3mm in diameter, density is 5,000
10,000 / m ² . C Third step: see (c) Plating 85 is applied to the entire laminated substrate material 8. The inner cylindrical surface of the circuit connection hole 83 drilled in the second step is also plated to form a via hole 84. D Fourth Step: Refer to (d) The surface of the laminated substrate material 8 is etched to form a circuit pattern 8
5a and 85b are formed to form a core substrate 88.

E Fifth Step (see (e)) An insulating layer 90 as a base material is bonded to the upper and lower surfaces of the core substrate 88.
Here, the insulating layer 90 to be bonded will be described with reference to FIG.
The insulating layer 90 includes a completely cured first insulating layer 90A,
Melting at step (125 ° C.), second step (180
C), semi-cured (B)
The second insulating layer 90B as a (stage) is laminated (coated). Further, the insulating layer in this embodiment is:
A release cloth 95a made of a microfiber cloth is adhered to the upper surface of the first insulating layer 90A to form a surface layer. The release cloth 95a is a synthetic fiber having a fiber diameter of about 8 μm, for example, an aramid fiber,
Made of polyester fiber. With ultrafine fibers, laser drilling is possible. Also, in this embodiment,
A reinforcing cloth 95b made of a fine aramid fiber cloth is also provided between the first insulating layer 90A and the second insulating layer 90B. By arranging the reinforcing cloth 95b, an insulating layer having high bending rigidity is formed, and planar accuracy is secured. Since the dielectric constant of aramid fiber is very close to the value of epoxy resin,
There is no adverse effect on impedance characteristics.

F Sixth Step: Refer to (f) The upper and lower surfaces of the core substrate 88 are simultaneously heated and pressed. The heating and pressurizing conditions at this time are as follows: temperature 125 ° C., 20 kg /
cm ² (first step). The second insulating layer 90B melts and flows into and fills the via hole 84, and the circuit groove 8B is filled.
Fill in 6. Excess molten resin flows out due to the pressurized pressure. Then, the temperature is set to 180 ° C. and the pressure is set to 20 kg / c.
The resin filling the via holes and grooves is cured by the heating and pressing steps of m ² (second step). In this process,
Extra-fine fiber cloth (release cloth 95) such as aramid resin
A, the reinforcing cloth 95B) exhibits high bending rigidity during lamination and bonding, so that planar accuracy that is as good as the unevenness of the circuit pattern 85 is ensured.

G: Seventh Step (see (g)) The release cloth 95a is released. By mechanically peeling off the release cloth (ultrafine fiber cloth) 95a on the surface after lamination and bonding,
Fine irregularities remain on the resin surface of the first insulating layer 90A to form a rough surface. This rough surface can improve the fixation of the copper plating circuit pattern in the next step. As described above, since the release cloth 95a made of a microfiber cloth can be mechanically peeled off, the operability is improved. H Eighth Step: Refer to (h) A hole 97 is formed in the insulating layer 90 by laser. I Ninth Step: Refer to (i) Surface circuits (conductor layers) 85c and 85d are formed by plating. Thus, a substrate having four layers of circuit patterns (85a, 85b, 85c, 85d) is completed by the build-up molding method.

In the multilayer printed circuit board having the above structure, the semi-cured second insulating layer has good resin flow (many).
Since the resin is applied in a sufficient amount of 15 μm in thickness, the resin is melted by heating and pressing in the first step to fill holes and grooves, and then excess resin is extruded from four sides. Also,
Even if the heating and pressurization in the first and second steps are excessive,
Since the first insulating layer, which is a completely cured resin layer, secures the thickness, if the heating and pressurization are sufficiently high, the thickness accuracy of the insulating layer can be secured even if the control accuracy in the pressing process is low. it can. Also, this substrate is a release cloth made of aramid fiber,
Further, since the reinforcing cloth forms the beam by sandwiching the cured first insulating layer, high bending rigidity can be obtained. Here, as a method for producing ultrafine fibers, there is a method of dividing a radial composite fiber of polyester and nylon, and the like. The fiber diameter of the aramid fiber at the current technical level is about 8 μm, so that it does not reach the rough surface (about 5 μm) of copper foil. However, ultrafine fibers such as polyester and nylon have a fiber diameter of about 1 μm. In terms of roughness, it is sufficiently comparable to the rough surface of copper foil.

As another example of a configuration in which the insulating layer is sandwiched between a release cloth and a reinforcing cloth made of ultrafine aramid fiber, a first insulating layer 91A shown in FIG. The stage is filled with a resin 92B, both surfaces of which are sandwiched between a release cloth 95a and a reinforcing cloth 95b made of ultrafine aramid fiber, and an adhesive layer 92C is formed by applying a B-stage resin. Alternatively, as shown in FIG. 8, the first insulating layer 93A
Is formed in a saw-like shape, the gap is filled with resin B of the B stage, and both surfaces thereof are formed of a release cloth 95 made of ultrafine aramid fiber.
a, a configuration in which the sheet is sandwiched by the reinforcing cloth 95b.

In the heating / pressing step, a difference (about 2 minutes) is given to the temperature raising and pressing time of the first step with respect to the upper and lower insulating layers of the core substrate, so that the semi-cured resin of the upper insulating layer, When the second insulating layer is melted and passes (fills) through the hole, the semi-cured resin of the second insulating layer in the lower insulating layer is softened and fused with the upper resin. The residual air in the via hole can be eliminated.

The temperature and pressure schedule in this case is as shown in FIG. Here, FIGS. 4 and 5
The method for manufacturing the substrate 9 will be described with reference to FIG. First, time t
_{In step 1} , the insulating layer provided on the upper surface of the substrate 88 is heated. When the temperature reaches 125 ° C. at time t ₂ , the second insulating layer 90
B begins to melt. Heating the insulating layer to be disposed on the lower surface of the substrate 88 at time t _3. In this case we have a gap between the time t ₁ and time t ₃ and 2 minutes. The second layer 90B of the insulating layer disposed on the lower surface of the substrate 88 also starts to melt at the time t ₄ when the temperature is 125 ° C.. Then, the via hole 84 and the groove 86 provided on the upper surface are filled with the molten resin of the second insulating layer 90B provided on the upper surface of the substrate 8 which is first melted.
Next, at a time lag of 2 minutes time t _4, the second insulating layer 90B is melted in the lower surface, the lower surface of the groove 86 is filled with discharge air. At time t ₅ , a pressure of 20 kg / cm ² is applied to the insulating layer disposed on the upper surface of the substrate 8 to ensure the filling of the via hole 84 and the groove 86 with the molten resin, and at the time t ₆ the lower surface is insulated. 20 kg / c pressure
By applying m ² , the via hole 84 and the groove 86 are filled with the molten resin, and the excess molten resin is pushed outward. ...... heating, and the first step of the pressure, the substrate 8 top, bottom surface of the groove, the molten resin filled the via holes, solidifies at the stage of a temperature of 180 ° C. at time t _7. At this stage, the first insulating layer 90A of the base material and the substrate 88 are bonded.

Here, as a method of giving a difference in the temperature raising time, a difference is given to the heat conduction from the hot plate of the hot press to the upper and lower surfaces of the substrate. For example, a thick stainless steel plate having poor heat conductivity is interposed on the lower surface of the substrate. Alternatively, there is a method of adjusting the power supply to the upper and lower heating boards to give a difference in the heating time.

In this embodiment, instead of the copper foil, the resin is cured in a state where the cloth of the synthetic resin fiber (polyester fiber, aramid fiber, etc.) is attached to the surface of the insulating layer, and the resin is cured. After the bonding, the microfiber cloth on the surface was mechanically peeled off, whereby a fine rough surface was formed on the resin surface, the plating adhesion performance was improved, and a good conductor layer could be formed. Also, by attaching ultra-fine fiber cloth of aramid fiber to the front and back of the cured insulating layer, a beam with a sandwich structure is formed and shows high bending rigidity, so the surface accuracy is as good as the unevenness of the circuit pattern it can. By mechanically peeling off the ultrafine fiber cloth on the surface as a release cloth, surface roughening can be achieved at low cost.

As described above, a material obtained by reinforcing a completely cured resin layer with a polyester fiber or an aramid fiber has a significantly increased flexural rigidity of the cured resin insulating layer. Even when pressed, it withstands bending moments and maintains high plane accuracy. Thus, in order to increase the bending rigidity and torsional rigidity of the substrate, it is effective to arrange the reinforcing cloth on the surface of the cured resin,
Further, by arranging it on the surface, it is possible to achieve a roughened surface on which the plating is attached.

In this embodiment, a method of manufacturing a multilayer printed circuit board by the build-up method has been described. In the batch press method, a semi-cured resin layer is provided on both the front and back surfaces of a completely cured insulating layer. The substrate of the present invention can be applied. In addition, since the collective pressing method does not perform drilling with a laser, reinforcement with glass fiber having a high melting point is possible. Further, when the first insulating layer is formed of a thermosetting resin having a molecular structure with a small resin flow instead of the completely cured resin of the insulating layer, the second insulating layer that is melted in the first step has a sharp dent. The first insulating layer does not participate in the filling of holes, etc., and the thickness accuracy of the insulating layer is much better than that of the conventional substrate, and the Surface accuracy has also been improved.

Embodiment 3 A manufacturing apparatus for continuously forming a multilayer printed board according to the present invention will be described. FIG. 10 is a schematic diagram of the entire apparatus, and FIG.
FIG. 4 is an enlarged explanatory view of a press portion. This apparatus shows a method of intermittently continuously forming a printed circuit board. The core substrate 88 cut to the specified size is sent out to the transport path R. On the upper and lower sides of the transport path of the core substrate 88, a copper foil with resin wound in a roll shape, that is, a base material 570 in which an insulating layer and a copper foil are superimposed.
Is arranged. The insulating layer includes a first insulating layer 5A made of a completely cured resin and a second insulating layer 5B made of a semi-cured resin. The insulating layer 5 having a two-layer structure with the copper foil 7 is drawn out of the roll from above and below the core substrate 88 which advances in the transport direction and polymerized. The insulating layer 5 is arranged to face the core substrate 88.

The core substrate 88 proceeds to the first press 200 while being sandwiched by the insulating layer 5, and is subjected to the first step of heating and pressing. The first press device 200 has an upper press 210 disposed above the transport path, and a lower press 220 disposed opposite the upper press 210 and below the transport path. The upper press 210 has a temperature of 125
° C and a press pressure of 20 kg / cm ² . Lower press 220, a front press portion 220A of setting conditions of a press pressure of 20 kg / cm ^2, temperature of 125 ° C., a rear press section 220B of the setting conditions of a press pressure of 20 kg / cm ²
It has. Front pressing section 220A and rear pressing section 2
20B have the same dimensions (D ₁ = D ₂ ). Upper press unit 210 and the lower press 220 intermittently repeats the pressurizing operation, the conveying device 500 has a configuration in which the distance D ₁ moves during depressurization.

A second press device 300 is disposed downstream of the first press device 200 in the transport direction. The second press device 300 includes an upper press 310 disposed at the upper part of the transfer path, and a lower press 320 disposed at the lower part of the transfer path opposite to the upper press 310 and having a temperature of 180 °.
° C and a press pressure of 20 kg / cm ² . The hot blast stove 40 is located downstream of the second pressing device 300 in the conveying direction.
0 is arranged. The hot blast stove 400 constitutes a high temperature environment. A transfer device 500 is disposed downstream of the hot blast stove 400, and the transfer path is intermittently moved by a specified size. The first press device 200 and the second press device 300 repeat pressurization and depressurization in synchronization with each other, and the transfer device executes the transfer of the distance D ₁ (D ₂ ) in accordance with the release of pressurization.

Next, the lamination by the first press device 200 and the second press device 300 will be described. The first step core substrate 88 first press device is the product Sotai laminated substrate composed of an insulating layer 5 of copper foil 7 on the top and bottom surfaces 20
0, the upper press 210 and the lower press 2
20 is heated and pressurized. At this time, the second insulating layer 5B is melted by heating at a temperature of 125 ° C.
The melted resin liquid flows into the circuit groove 86 and the via hole 84 of the core substrate 88 under a press pressure of 20 kg / cm 2. In the lower part of the core substrate 88, the excess of the molten resin on the upper part intrudes through the via holes 86 in the front pressing part 220 </ b> A. In the rear pressing part 220B, the second insulating layer 5B is melted by heating at a temperature of 125 ° C.
The circuit groove 85 is filled with a press pressure of kg / cm 2, and the via hole 84 is filled. Excess molten resin is discharged from the gap between the adjacent core substrates 88 or the end of the substrate.

Second Step The core substrate 88 in which the circuit grooves and the via holes are filled with the molten resin of the second insulating layer 5B is placed in the second pressing device 30.
Transported to zero. The second pressing device 300 heats and presses the upper and lower portions of the laminated substrate at a temperature of 180 ° C. and a pressing pressure of 20 kg / cm ² to cure the molten resin. Here, for example, the pressurizing time in the first step and the second step is 10 seconds,
By setting the depressurization time to 2 seconds, the resin melts, cures,
And the transfer can be performed smoothly.

Third Step The laminated substrate in which copper foil is laminated on both surfaces of the core substrate 88 with an insulating layer interposed therebetween is conveyed into a hot-blast furnace 400 and has a temperature of 150 ° C. to 18 ° C.
It is placed in an atmosphere of 0 ° C. to stabilize the curing of the resin.

In the above-described apparatus, the substrate made of the insulating layer with the copper foil has been described as the insulating layer in which the fully cured first insulating layer is provided on the entire surface. For example, as shown in FIG.
When using an insulating layer in which the second insulating layer 50A is arranged in a ridge shape, the ridge direction y of the first insulating layer 50A of the completely cured resin is orthogonal to the transport direction x as shown in FIG. With such arrangement, the efficiency of discharging the air and the molten resin is improved. In addition, as means for providing a difference in heating timing between the upper and lower surfaces of the core substrate, in addition to the above, a time difference is provided for heating the lower press with respect to the upper press, and the heat conductivity of the press surface of the lower press is low. There are means for disposing the raw material, lowering the electric power supplied to the lower press, and delaying the reaching of a specified temperature.

As described above, this apparatus can continuously mold a substrate in which a copper foil is formed on both surfaces of a core substrate via insulating layers having a specified thickness. In addition, since the cured resin of the first insulating layer and the molten resin of the second insulating layer fuse with each other by the heating in the first step and the second step, delamination hardly occurs and multilayer lamination becomes easy, and the manufacturing cost is reduced. Is cheaper. This apparatus can also be applied to a substrate on which ultrafine fibers are formed instead of copper foil.

[0050]

As described above, the multilayer printed circuit board according to the present invention in which the base material of the printed circuit board is laminated is different from the fully cured first insulating layer having improved layer thickness dimensional accuracy.
Since the second insulating layer is a semi-cured resin formed of the same component, the molten resin filling the circuit grooves and via holes is integrated with the first insulating layer to ensure electrical and physical characteristics. And the surface accuracy can be increased, and peeling between layers hardly occurs. The insulating layer reinforced by disposing a reinforcing material , for example, a release cloth or a reinforcing cloth on the front and back surfaces of the completely cured first insulating layer forming the resin layer, or by blending fibers such as aramid fibers, is bent. The rigidity is remarkably increased, the toughness against bending moment against the unevenness of the circuit pattern of the conductor layer is maintained, and the planar accuracy can be maintained at a high level.

The method for manufacturing a multilayer printed board according to the present invention comprises:
A substrate having high surface flatness accuracy with high layer thickness accuracy of the insulating layer can be easily formed. In addition, peeling made of microfiber on the surface
By arranging the cloth , the bending and torsional rigidity by pressurization can be increased, and the surface can be easily roughened.

The apparatus for manufacturing a multilayer printed circuit board can easily and continuously manufacture an insulating layer having a uniform thickness and a board having high plane accuracy.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a base material.

FIG. 2 is a sectional view showing another embodiment of the base material.

FIG. 3 is a cross-sectional view showing another embodiment of the base material.

FIG. 4 is an explanatory view of forming a substrate by build-up.

FIG. 5 is an explanatory view of forming a substrate by build-up.

FIG. 6 is an explanatory view of forming a substrate using another base material.

FIG. 7 is an explanatory view of forming a substrate using another base material.

FIG. 8 is an explanatory view of forming a substrate using another base material.

FIG. 9 is a graph showing a schedule of temperature and pressure in the heating / pressing device.

FIG. 10 is an overall schematic diagram of a manufacturing apparatus.

FIG. 11 is an enlarged explanatory view of a heating / pressing device.

FIG. 12 is a perspective view of a base material.

FIG. 13 is an explanatory view of a conventional batch molding method.

FIG. 14 is a graph showing a schedule of temperature and pressure in a conventional heating / pressing device.

FIG. 15 is an explanatory view of forming a substrate by conventional build-up.

FIG. 16 is an explanatory view of forming a substrate by conventional build-up.

FIG. 17 is an explanatory view of forming a substrate showing another example of a conventional build-up.

[Explanation of symbols]

 3,88 core substrate 5A, 90A first insulating layer 5B, 90B second insulating layer 7,82 copper foil 84 via hole 85 circuit pattern 86 groove 95a release cloth 95b reinforcing cloth 200 first heating / pressing device 300 second heating / pressing device 400 stove 500 transfer device

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-244563 (JP, A) JP-A-10-13016 (JP, A) JP-A-7-131182 (JP, A) JP-A-7-131 336049 (JP, A) JP 719972 (JP, B2) JP 5-12876 (JP, B2) JP 8-31693 (JP, B2) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H05K 3/10-3/46

Claims (7)

(57) [Claims] 1. A method for manufacturing a multilayer printed circuit board, comprising laminating a conductor layer around a substrate serving as a core via an insulating layer made of a thermosetting resin, wherein a release cloth is provided around the substrate serving as a core. A laminating step of laminating the insulating layer to be laminated on the upper and lower surfaces of the substrate with the release cloth as the outer surface; a heating / pressing step of heating and pressing the laminated material; and a release cloth peeling step of releasing the release cloth of the laminated material. A conductor layer forming step of forming a conductor layer on the laminated material, wherein the insulating layer comprises a first insulating layer formed of a completely cured resin having a release cloth disposed on a surface thereof, and a semi-cured resin. In the laminating step, the second insulating layer is simultaneously laminated on the upper and lower surfaces of the substrate so as to face the conductor layer of the object to be laminated, and the heating / pressing step is performed in the second laminating step. A first step set to a temperature at which the resin of the insulating layer melts;
A second step set to a temperature at which the resin of the melted second insulating layer is cured, wherein in the heating / pressing step, the molten resin of the second insulating layer melted in the first step fills the circuit groove of the conductor layer of the stacked body, a via hole, molten resin is cured in a second step, that Do the adhesive to the conductor layer of the first insulating layer and the stacked body Together with on the board
Melting of resin in the first step of heating and pressurizing the surface
Start timing and the first of heating and pressing on the lower surface of the substrate
Time difference in the resin melting start timing
When the molten resin in the insulating layer
The second insulation of the insulating layer disposed on the lower surface when filling
A method for manufacturing a multilayer printed circuit board , wherein a layer is configured to be softened , a release cloth is mechanically peeled in the release cloth peeling step, and a rough surface for attaching a conductor layer is formed on a surface of the first insulating layer. 2. A thermosetting resin comprising a core substrate as a center.
Manufacture of multilayer printed circuit boards in which conductor layers are laminated via insulating layers
In forming apparatus, the transfer means of the core substrate, and the insulating layer supply means disposed in the core substrate transport path, the first heating and pressing means disposed downstream of the insulating layer supply means
And a second heating and pressurizing unit disposed downstream of the first heating and pressurizing unit.
Means, and the insulating layer supplied from the insulating layer supply means is completely cured.
A first insulating layer made of resin and a semi-cured resin
A second insulating layer to be formed, wherein the second insulating layer is a core substrate.
And the first heating / pressing means melts the resin of the second insulating layer.
And the second heating / pressurizing means is a temperature at which the molten resin is cured.
And the first heating and pressing means and the second heating and pressing means are the same.
In addition to the pressure and pressure reduction drive,
Depressurizing ties of the first heating / pressing means and the second heating / pressing means
Many are configured to be intermittently driven according to the
Equipment for manufacturing printed circuit boards. 3. The method according to claim 1, wherein the first heating / pressurizing means is mounted on the substrate.
Melting the resin of the second insulating layer of the layered insulating layer and melting
Fill the circuit grooves and via holes of the conductor layer with resin,
The second heating / pressurizing means cures the molten resin
3. The method according to claim 2, wherein the first insulating layer and the substrate are bonded together.
Manufacturing equipment for multilayer printed circuit boards. 4. The method according to claim 1, wherein the first heating / pressurizing means is configured to transfer a substrate.
Delay heating one side of a path relative to the other
3. The method according to claim 2, further comprising heating delay means.
Equipment for manufacturing printed multilayer printed circuit boards. 5. The heating delay means according to claim 1, wherein said heating delay means is a heating start timing.
5. The apparatus for manufacturing a multilayer printed circuit board according to claim 4, wherein a time difference is set in the multi-layer printed circuit board. 6. The heating delay means includes a pressurizing member having a low thermal conductivity.
5. The apparatus for manufacturing a multilayer printed circuit board according to claim 4, wherein a board is provided . 7. The heating delay means sets a low power supply.
An apparatus for manufacturing a multilayer printed circuit board according to claim 4, wherein