JP3823940B2 - Method for manufacturing circuit-formed substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a circuit forming substrate and a circuit forming substrate, or a circuit forming substrate material.
[0002]
[Prior art]
As electronic devices have become smaller and higher in density in recent years, the adoption of double-sided and multi-layer boards for circuit-forming boards on which electronic components are mounted has increased from the conventional single-sided board, and more circuits can be integrated on the board. Development of a density circuit forming substrate has been carried out, and various methods for connecting layers have been proposed. For example, a circuit that performs interlayer connection using a connecting means such as fine hole processing by laser and conductive paste A formation substrate has also been proposed (Japanese Patent Laid-Open No. 6-268345).
[0003]
Further, as a request from the user using the substrate, it is necessary to make the thickness accuracy of the finished substrate more precise on the premise that the substrate is used for a high-frequency circuit or a high-speed operation circuit.
[0004]
As a process for manufacturing a circuit-formed board, holes are made in the board material, paste filling, etc. is performed as necessary, single layer or multiple layers are laminated, and then compression or integrated molding is performed using a hot press A method of curing the resin used for the substrate material is often used.
[0005]
In this case, the thickness of the circuit-formed substrate is almost determined by the thickness variation of the substrate material itself and the uniformity of compression during hot pressing.
[0006]
[Problems to be solved by the invention]
However, a normal substrate material is a B-stage made by impregnating a thermosetting resin into a reinforcing material made of glass or organic fiber, and the thermosetting resin flows out when compressed by hot pressing. Therefore, the peripheral portion of the substrate material tends to be thin and the central portion tends to be relatively thick.
[0007]
When a woven fabric having regular fibers in the XY direction, such as a glass fiber woven fabric used for a normal glass epoxy printed wiring board, is used as a reinforcing material, a thermosetting resin is used in the reinforcing material during hot pressing. Since the flow resistance at the time of flow is relatively small, the above-mentioned tendency is difficult to appear, but when nonwoven fabric is used as a reinforcing material, the flow resistance is large and the phenomenon that the compression of the central part is less than the peripheral part is a phenomenon. It is confirmed.
[0008]
In particular, the amount of compression required for the connection between the layers in the method of filling the holes formed in the substrate material with conductive paste that develops electrical continuity by compression as shown in the prior art and using it for the connection between the layers Must be strictly controlled, and if the compression is insufficient, the connection reliability between layers may not be ensured. The required accuracy is required to be much higher than the specifications required by users in order to ensure the characteristics of the substrate.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable method for producing a circuit-formed substrate and a circuit-formed substrate or a material produced using the method, while ensuring plate thickness accuracy as the quality of the circuit-formed substrate.
[0010]
[Means for Solving the Problems]
In the method for producing a circuit-formed substrate of the present invention, a laminating step of laminating a film on a B-stage substrate material containing a thermosetting resin, a hole-forming step of forming a through or non-through hole in the substrate material , A filling step of filling the through or non-through holes with conductive paste, a step of peeling the film from the substrate material , a pressing step of placing metal foil on both sides of the substrate material and compressing in the thickness direction, and the metal A step of forming a circuit by patterning a foil, and a void forming step of hollowing out a part of the substrate material before the laminating step or after the filling step and before the pressing step , and the gap portion The formed position is a position including the position where the circuit is formed or a position excluding the position where the hole is formed, and before filling the plurality of holes. Conductive paste, in which the thermosetting resin in the substrate material during the pressing step is characterized in that it is uniformly compressed by flowing into the gap portion.
[0011]
According to the present invention, the compression of the substrate material in the pressing process can be made uniform or efficient, the plate thickness accuracy of the circuit-formed substrate can be ensured, and the reliability of the interlayer connection can be increased.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The invention described in claim 1 includes a laminating step of laminating a film on a B-stage substrate material containing a thermosetting resin, a hole forming step of forming a through or non-through hole in the substrate material, and a conductive paste Filling the through or non-penetrating holes, peeling the film from the substrate material , pressing the metal foil on both sides of the substrate material and compressing in the thickness direction, and patterning the metal foil And forming a circuit; and a void forming step of hollowing out a part of the substrate material before the laminating step or after the filling step and before the pressing step , and the void portion is formed. The position is a position including a position where the circuit is formed or a position excluding a position where the hole is formed, and the conductive paste filled in the plurality of holes is Wherein are those thermosetting resins in the substrate material during the pressing step is a method of manufacturing circuit board, characterized in that it is uniformly compressed by flowing into the space portion, formed at the gap formation process Since the voids become cavities into which the substrate material flows during pressing, compression can be achieved uniformly during compression by pressing, and the voids are covered with a film in the filling process because the voids are formed before the laminating process. penetration of conductive paste into the cage gap portion have a effect such as can be prevented, or has the effect of such conductive paste into the gap does not enter to form an air gap after the filling process.
[0014]
In addition, according to the invention described in claim 1 or claim 2, it is possible to easily achieve effects such as uniform plate thickness or compressibility, and ensuring interlayer connection reliability. Furthermore, as a matter of course, by forming a gap portion at a position excluding the through hole, the design freedom of the formation position of the conduction hole and the wiring capacity can be improved, and high-quality, uniform plate thickness and high-quality double-sided or multilayer The circuit forming substrate is obtained.
[0015]
In addition, when the press process of the present invention is a so-called heat press that involves heating, melting and molding the substrate material and then thermosetting, the substrate material is melted by heat, so that the action of the substrate material flowing into the voids is efficient. Is to be done.
[0016]
Further, when a circuit forming substrate having a metal foil on at least one side is manufactured using the method for manufacturing a circuit forming substrate according to claim 3 of the present invention, the prepreg or the B stage resin sheet is melted in the pressing step. Without flowing out to the outside of the substrate material, it flows into the gap, and uniform compression can be realized efficiently, and the interlayer connection reliability by the conductive paste can be enhanced.
Furthermore, a multilayer circuit-formed substrate can be obtained using the method for producing a circuit-formed substrate according to claim 4 of the present invention.
[0017]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
[0018]
(Embodiment 1)
FIG. 1 is a process cross-sectional view illustrating a method for manufacturing a circuit forming substrate according to a first embodiment of the present invention. The substrate material 1 is a composite material of a thermosetting resin 2 and an aramid fiber 3 as shown in FIG. The thermosetting resin 2 is not completely cured, but is in a so-called B stage state including an uncured portion, and the substrate material 1 is usually called a prepreg. As the substrate material shown in this embodiment, an aramid fiber nonwoven fabric impregnated with a thermosetting epoxy resin diluted with a solvent and B-staged through a slight heating and drying process can be used.
[0019]
In addition, the resin film 12 that can be peeled off is laminated on both surfaces of the substrate material 1 in order to accurately fill the hole with the conductive paste without causing the conductive paste to bleed or protrude in the vicinity of the through or non-through hole. .
[0020]
Next, as shown in FIG. 1 (b), a laser 4 is irradiated onto the resin film 12 and the substrate material 1 to form a through hole 5.
[0021]
Next, as shown in FIG. 1C, the through-hole 5 is filled with the conductive paste 6 by using printing means or the like.
[0022]
Next, as shown in FIG. 1 (d), a circular gap 7 is formed in the substrate material 1. Various methods such as mechanical punching with a die punch that can be easily inlined and processing with an energy beam such as a laser can be used for forming the gap 7. The void portion 7 here is a small gap, that is, a void portion when the aramid fiber 3 is impregnated with the thermosetting resin 2 or made into a B-stage when the substrate material 1 is supplied in a prepreg state (see FIG. (Not shown) means that formed after the prepreg state.
[0023]
Next, as shown in FIG. 1E, after the resin film 12 is peeled off, the substrate material 1 is sandwiched between the metal foil 8a and the metal foil 8b, and heated and pressurized using a hot press apparatus (not shown). The thermosetting resin 2 is melted and molded by heating and pressing, and then thermoset. At that time, as indicated by an arrow in FIG. 1 (f), the thermosetting resin 2 protrudes into the peripheral portion of the substrate material 1 and also flows into the gap portion 7, whereby the substrate material 1 is compressed in the thickness direction. .
[0024]
When there is no gap 7, the peripheral part is naturally thin and the central part is molded into a thick shape. This is because the flow resistance for allowing the thermosetting resin 2 in the vicinity of the central portion to flow in the peripheral direction is much larger than when the thermosetting resin 2 in the peripheral portion flows out of the substrate material 1. Although the above-mentioned air hole portion is related to this compression action, the factor due to the flow into the peripheral portion or the gap portion 7 is a larger and dominant element in volume. Although the gap 7 is completely filled with the thermosetting resin 2 in the drawing, it is not necessary to completely fill the gap 7 when the gap 7 is not used as a final product.
[0025]
After molding, the shape becomes as shown in FIG. 1G, and the metal foil 8 a and the metal foil 8 b are electrically connected by the conductive paste 6. The resistance value of the connection by the conductive paste 6 and the reliability thereof are closely related to the compression amount at the time of heating and pressurization, and in order to obtain a uniform connection resistance within the substrate, it is uniform as in this embodiment. Naturally, a production method that can achieve a good compression is preferable. Next, the peripheral part is cut into a desired dimension, and the metal foil 8 is patterned into a desired shape to form a circuit 9 to obtain a double-sided circuit forming substrate as shown in FIG. The position where the circuit 9 is formed may include the position where the gap 7 is formed as shown in FIG.
[0026]
The effect of the present embodiment is noticeable when the nonwoven fabric is used as the reinforcing material as described above. This is because a glass fiber woven fabric used for a general glass epoxy substrate regularly has fibers in the X and Y directions, so the resistance of the resin to flow inside the woven fabric during heating and pressurization is low, and thickness variations are unlikely to occur. However, in the case of a non-woven fabric, the resistance of the resin to flow inside the non-woven fabric is considerably high and thickness variation is likely to occur.
[0027]
In the present embodiment, the double-sided circuit formation substrate has been described, but it goes without saying that a multilayer circuit formation substrate can be obtained by repeating the process a plurality of times.
[0028]
Furthermore, the present invention can be applied to the manufacture of a circuit forming substrate using a film-like B-stage material without a reinforcing material.
[0029]
In addition, for a circuit-formed substrate that does not use a conductive paste, the effect of making the substrate plate thickness uniform according to the present invention is effective for applications that require high-frequency characteristics of the substrate or particularly where plate thickness accuracy is required.
[0030]
Further, the size of the metal foil 8 causes a problem that when the flow of the thermosetting resin 2 to the peripheral portion reaches the outside of the metal foil 8, it causes a problem of adhering to an intermediate plate or the like used in the hot press process. However, there is a demand to reduce the margin as much as possible because it is a loss that does not become a product substrate, and due to the effect of the present invention, the flow out amount to the peripheral part is reduced or made uniform. Therefore, the size of the metal foil 8 can be made closer to the substrate material 1 to reduce loss and reduce the cost of the metal foil 8.
[0031]
Further, in the present embodiment, the step of forming the gap portion 7 is made of resin in order to minimize the influence of moisture absorption on the gap portion 7 after filling with the conductive paste and to prevent the conductive paste in the hole from dropping off. Although it was performed before peeling of the film, it is also possible to form a void with a laser when processing the through hole in order to increase productivity.
[0032]
(Embodiment 2)
FIG. 2 is a process cross-sectional view illustrating a method of manufacturing a circuit forming substrate according to the second embodiment of the present invention.
[0033]
As shown in FIG. 2A, a prepreg 1 having a through hole, filled with a conductive paste 6 and further formed with a void 7 is prepared as a part of the substrate material. Next, as shown in FIG. 2B, the metal foil 8, the above-described prepreg, and the two-layer core circuit forming substrate 10 are stacked and arranged as a substrate material. At that time, alignment between the materials (1, 10) or temporary fixing is performed as necessary so that conductive connection between the layers can be achieved.
[0034]
Next, the substrate material is compressed by hot pressing to form a laminate as shown in FIG. Further, as shown in FIG. 2D, the end face is cut at a predetermined position, and the metal foil 8 on the surface is patterned by a method such as etching to form a circuit 9 to obtain a multilayer circuit forming substrate having a four-layer structure. .
[0035]
(Embodiment 3)
FIG. 3 is a cross-sectional view showing a circuit-forming substrate material according to the third embodiment of the present invention. The substrate material 1 is a prepreg which is a composite material of a thermosetting resin 2 and an aramid fiber 3, and has the same properties as the substrate material 1 shown in the first embodiment. However, the gap 7 is already formed in this state.
[0036]
Various methods such as processing in the aramid fiber nonwoven fabric state before impregnation with the thermosetting resin 2 or processing after entering the prepreg state are possible for the formation of the void portion 7, and laser or punching is used as a processing tool. Such as mechanical punching can be used.
[0037]
In the present embodiment, since the gap 7 is formed when the substrate material 1 is supplied, a high-quality circuit-forming board can be formed without adding a step for machining the gap during the production of the circuit-formed board. Manufacturing is possible. However, in the case where the manufacturing process includes a process such as printing of the conductive paste as described in the first embodiment, a case where the gap portion becomes a problem is assumed. In that case, the formation of the void portion may be included in the process as in the first embodiment.
[0038]
【The invention's effect】
As described above, the circuit forming substrate manufacturing method and the substrate material according to the present invention compress the substrate material in the thickness direction when the circuit forming substrate is manufactured using a substrate material composed of a single material or a plurality of materials. Including a pressing step, and a manufacturing method including a gap forming step in which a part of the substrate material is hollowed out at one or a plurality of locations before the pressing step, or a sheet-like reinforcing material is impregnated with a thermosetting resin to form a B stage. By using a substrate material that is later hollowed out at one or more locations to form a void, a circuit-formed substrate can be produced without causing variations in the thickness of the substrate material by press working. It is possible to provide a highly reliable circuit forming substrate.
[Brief description of the drawings]
FIG. 1 is a process cross-sectional view of a circuit forming substrate manufacturing method according to a first embodiment of the present invention. FIG. 2 is a process cross-sectional view of a circuit forming substrate manufacturing method according to a second embodiment of the present invention. 3 is a cross-sectional view of a circuit-forming substrate material according to a third embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 Board | substrate material 2 Thermosetting resin 3 Aramid fiber 4 Laser 5 Through-hole 6 Conductive paste 7 Cavity part 8 Metal foil 9 Circuit 10 Core circuit formation board 12 Resin film

Claims (4)

A laminating step of laminating a film on a B-stage substrate material containing a thermosetting resin ;
A hole forming step of forming a through or non-through hole in the substrate material ;
A filling step of filling the through or non-through hole with a conductive paste ;
Peeling the film from the substrate material;
A pressing process in which metal foil is disposed on both sides of the substrate material and compressed in the thickness direction ;
Patterning the metal foil to form a circuit;
A gap forming step for hollowing out a part of the substrate material before the laminating step or after the filling step and before the pressing step ;
The position where the gap is formed is a position including a position where the circuit is formed or a position excluding a position where the hole is formed,
The conductive paste filled in the plurality of holes is uniformly compressed by the thermosetting resin in the substrate material flowing into the gap during the pressing step . Production method. 2. The gap according to claim 1, wherein the void portion into which the thermosetting resin has flowed includes one in which the thermosetting resin is completely filled and one in which the thermosetting resin is not completely filled. A method for manufacturing a circuit-formed substrate. In the pressing step, the thermosetting resin in the substrate material does not flow out of the substrate material, or the amount of the thermosetting resin flowing out to the periphery of the substrate material is substantially uniform with the size of the substrate material. The method for manufacturing a circuit-formed substrate according to claim 1, wherein the substrate material is compressed as described above. Preparing a substrate material having through holes and voids filled with a conductive paste;
Stacking the metal foil, the substrate material, and the core circuit forming substrate;
Compressing it by hot pressing to form a laminate,
Forming a circuit by patterning the metal foil of the laminate,
The position where the gap is formed is a position including a position where the circuit is formed or a position excluding a position where the through hole is formed,
The circuit-forming substrate, wherein the conductive paste filled in the plurality of through holes is uniformly compressed by the thermosetting resin in the substrate material flowing into the gap during the pressing step. Manufacturing method.

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