JP2000307246A - Manufacture of circuit forming substrate and material thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure board thickness precision by providing a gap forming process for hollowing one part or plural parts in a part of a substrate material before a press process for compressing the substrate material in a thickness direction. SOLUTION: Resin films 12 that can be peeled are laminated on both faces of a substrate material 1 using the composite material of thermosetting resin 2 and aramid fiber 3. The resin films 12 and the substrate material 1 are irradiated with laser 4 and a through hole 5 is formed. The through hole 5 is filled with conduction paste 6 by using the means of printing and the like. Circular gap parts 7 are formed in the substrate material 1 by mechanical punching by a die punch, The resin films 12 are peeled and the substrate material 1 is sandwiched by metallic foils 8a and 8b. It is heated and pressurized by using a heat pressing device. Thermosetting resin 2 is melted, molded and is cured. A peripheral part is cut in a desired size, the metallic foils 8a and 8b are patterned and a circuit 9 is formed.

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 circuit board and a material for the circuit board.

[0002]

2. Description of the Related Art With the recent miniaturization and high-density of electronic equipment, circuit-forming boards on which electronic components are mounted have been increasingly adopted from conventional single-sided boards to double-sided, multi-layer boards. Development of a high-density circuit formation substrate that can be integrated into a substrate has been carried out, and various methods of connecting layers have been proposed, for example, using a fine hole processing by a laser and a connecting means such as a conductive paste. A circuit forming substrate for performing interlayer connection has also been proposed (JP-A-6-268345).

[0003] In addition, as a demand of a user who uses a substrate, it is necessary to make the thickness accuracy of a completed 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 of manufacturing a circuit forming substrate, holes are formed in a substrate material, processing such as filling of paste is performed as necessary, a single layer or a plurality of layers are laminated, and then compressed and integrated using a hot press. A method of molding and curing the resin used for the substrate material is often used.

In this case, the thickness of the circuit-forming substrate is almost determined by the thickness variation of the substrate material itself and the uniformity of the compression during hot pressing.

[0006]

However, a normal substrate material is a B-stage made by impregnating a thermosetting resin into a reinforcing material such as glass or organic fiber, and when the material is compressed by a hot press. Since the thermosetting resin flows outward to compress in the thickness direction, the peripheral portion of the substrate material tends to have a small thickness and the central portion tends to have a relatively large thickness.

When a woven fabric having fibers regularly present in the XY directions, such as a glass fiber woven fabric used for a normal glass epoxy printed wiring board, is used as a reinforcing material, the thermosetting resin causes heat to flow through the reinforcing material. The above tendency is unlikely to appear because the flow resistance when flowing during pressing is relatively small, but when a nonwoven fabric is used as a reinforcing material, the compression in the central part is less than in the peripheral part because the flow resistance is large. The phenomenon is confirmed.

[0008] In particular, in a method of filling a hole formed in a substrate material with a conductive paste which exhibits electrical conduction by compression as shown in the prior art and using the paste for connection between layers, it is necessary for connection between layers. It is necessary to strictly control the amount of compression, 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 the user to ensure the characteristics of the substrate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and a material for manufacturing a circuit-forming board, which can ensure the thickness accuracy as the quality of the circuit-forming board and have high reliability.

[0010]

In the method of manufacturing a circuit forming substrate according to the present invention, when a circuit forming substrate is manufactured using a substrate material composed of a single material or a plurality of materials,
The method includes a pressing step of compressing the substrate material in the thickness direction, and a gap forming step of hollowing out one or more portions of the substrate material before the pressing step.

According to the present invention, the compression of the substrate material in the pressing step can be made uniform or efficient, and the thickness accuracy of the circuit forming substrate can be ensured and the reliability of interlayer connection can be improved. It is.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, when manufacturing a circuit forming substrate using a substrate material composed of a single material or a plurality of materials, the substrate material is compressed in the thickness direction. A press forming step, and a method of manufacturing a circuit forming board, characterized by comprising a gap forming step of hollowing out a part of the substrate material before the pressing step. Since the voids serve as cavities into which the substrate material flows during pressing, uniform compression can be achieved during compression by pressing.

According to a second aspect of the present invention, there is provided the method of manufacturing a circuit-formed substrate according to the first aspect, further comprising a step of forming a plurality of voids in a part of the substrate material. Since the voids formed in the void forming step serve as a plurality of cavities into which the substrate material flows during pressing, uniform compression can be efficiently realized at the time of pressing by pressing.

According to a third aspect of the present invention, there is provided the method of manufacturing a circuit-formed substrate according to the first aspect, wherein the voids have a circular shape. Therefore, uniform compression can be efficiently realized at the time of compression by a press.

The invention according to claim 4 of the present invention is characterized in that the pressing step is pressurization accompanied by heating, and is a so-called hot press in which the substrate material is melted, molded, and then thermally cured. 1. The method according to claim 1, wherein the substrate material is melted by heat so that the substrate material flows into the voids efficiently.

According to a fifth aspect of the present invention, there is provided the method of manufacturing a circuit-formed substrate according to the first aspect, wherein the voids are formed by using laser processing.
This has the effect that fine voids can be formed at accurate positions.

According to a sixth aspect of the present invention, there is provided the method for manufacturing a circuit-formed substrate according to the first aspect, wherein the voids are formed by punching using a die punch. In addition, it is possible to easily realize improvement in productivity and in-line conversion.

According to a seventh aspect of the present invention, there is provided the prepreg or B-stage resin sheet, wherein the substrate material comprises a prepreg or B-stage resin sheet and a metal foil disposed on both or one side of the prepreg or B-stage resin sheet. The method according to claim 1, wherein a void is formed in the resin sheet, and no void is provided in the metal foil.
When the prepreg or the B-stage resin sheet is melted in the pressing step, the prepreg or the B-stage resin sheet does not flow out of the substrate material but flows into the void portion, and the effect of the present invention can be exerted without contaminating the mirror plate or the like sandwiching the substrate material. Things.

The invention according to claim 8 of the present invention is a laminate comprising a core circuit forming substrate and a prepreg or B-stage resin sheet disposed on one or both sides of the core circuit forming substrate and the laminate. Made of metal foil disposed on both sides or one side of the prepreg or B
The method according to claim 1, wherein a void is formed in one or more of the stage resin sheets, and the board thickness is increased by adding the circuit formed substrate to the substrate material. This has the effect of obtaining a uniform and high-quality multi-layer circuit forming substrate.

According to a ninth aspect of the present invention, there is provided a hole forming step of forming a penetrating or non-penetrating hole in a substrate material before a pressing step, and filling the penetrating or non-penetrating hole with a conductive paste. 2. A method for manufacturing a circuit-formed substrate according to claim 1, further comprising a filling step, wherein the compression ratio in the thickness direction in the pressing step of the entire substrate is made uniform, and the interlayer between conductive layers is formed. Connection reliability can be ensured.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a circuit-forming substrate according to the ninth aspect, wherein a void is formed at a position other than a through hole or a non-through hole filled with a conductive paste. High-density, uniform-thickness, high-quality double-sided or multi-layer circuit with improved design flexibility and wiring accommodating position of through or non-through conductive holes filled with conductive paste A formed substrate is obtained.

[0022] According to the eleventh aspect of the present invention, a step of laminating a resinous film to a substrate material before a hole forming step of forming a penetrating or non-penetrating hole; The method according to claim 9, further comprising a step of peeling the resinous film from the substrate material after the filling step of filling the holes. The conductive paste can be accurately filled in the holes without bleeding or oozing out of the conductive paste near the holes, and high-conductivity and high-quality double-sided or multi-layer circuit formation with uniform plate thickness A substrate is obtained.

According to a twelfth aspect of the present invention, there is provided the circuit according to the ninth aspect, further comprising a void forming step after the filling step of filling the conductive paste into the through holes or the non-through holes. It is a method of manufacturing a formed substrate,
Forming the gap after the filling step immediately before the pressing step has an effect of minimizing a dimensional change of the substrate material due to a factor of moisture absorption in the gap.

According to a thirteenth aspect of the present invention, a void forming step is provided before the filling step of filling a conductive material into a hole penetrating or not penetrating the substrate material. Which can prevent the conductive paste filled in the penetrating or non-penetrating holes from dropping out of the holes, and can be easily in-lined to improve the productivity. It is.

The invention according to claim 14 of the present invention is characterized in that a void forming step is provided in a hole forming step of forming a penetrating or non-penetrating hole in a substrate material. A method for manufacturing a circuit-formed substrate, which prevents the conductive paste filled in through-holes or non-through-holes from dropping out of the holes, and improves productivity by forming voids simultaneously with the formation of holes. Can be done.

According to a fifteenth aspect of the present invention, there is provided the method of manufacturing a circuit-formed substrate according to the eleventh aspect, further comprising a step of forming a gap after the step of laminating the resinous film on the substrate material. In addition to preventing the conductive paste filled in through or non-penetrating holes from falling out of the holes, productivity can be improved by forming voids simultaneously with the formation of holes, and furthermore, the conductivity can be improved. By filling the conductive paste into the holes without causing bleeding or protrusion of the paste, it is possible to obtain a high-quality double-sided or multilayer circuit-forming substrate having high conduction reliability and a uniform plate thickness.

The invention according to claim 16 of the present invention comprises a step of forming a gap between the step of filling the conductive paste into the holes penetrating or not penetrating and the step of peeling the resinous film from the substrate material. 12. A method for manufacturing a circuit-formed substrate according to claim 11, wherein a gap is formed after the filling step to minimize a dimensional change of the substrate material due to a factor of moisture absorption in the gap. In addition, the presence of the resinous film prevents the conductive paste filled in the penetrating or non-penetrating holes from dropping out of the holes, and prevents the conductive paste from bleeding or protruding. By filling, a high-quality double-sided or multi-layer circuit-formed substrate having a high conduction reliability and a uniform plate thickness can be obtained.

The invention according to claim 17 of the present invention is the method according to claim 7 or 8, wherein the reinforcing material of the prepreg is made of a nonwoven fabric. The configuration of the present invention has an effect that uniformity can be ensured even in a nonwoven fabric that is difficult to obtain, and advantages such as surface smoothness of the nonwoven fabric can be utilized.

The invention according to claim 18 of the present invention is characterized in that the number or volume of the voids formed in the void forming step differs between the central part and the peripheral part of the substrate material as the amount per unit area of the substrate material. The number and volume of the voids can be optimized corresponding to the case where the compressibility in the pressing step differs at the in-plane position of the substrate material, The effects of the invention can be maximized.

The invention according to claim 19 of the present invention is characterized in that the number or volume of the voids formed in the void forming step in the central portion of the substrate material is larger than that in the peripheral portion as an amount per unit area. A method for manufacturing a circuit-formed substrate according to claim 18, wherein in the pressing step, the substrate material component flows out of the substrate material, so that the substrate material component is easily compressed, and the central portion of the substrate material has a flow resistance flowing around. In contrast to the phenomenon that it is difficult to compress because it is large, there is an effect that uniformity of compressibility and plate thickness is realized by providing many voids in the center.

The invention according to claim 20 of the present invention is characterized in that the number or volume of the voids formed in the void forming step in the peripheral portion of the substrate material is larger than that in the central portion as the amount per unit area. 19. A circuit pattern formed on a surface of a core circuit forming substrate when the core circuit forming substrate is used as a part of the substrate material, as an example. When the peripheral part of the substrate material is harder to compress than the central part due to the shape, circuit pattern distribution, etc., many voids in the peripheral part cancel the tendency and uniformity of compressibility and plate thickness Is realized.

[0032] The invention according to claim 21 of the present invention is characterized in that the amount of the substrate material component flowing around the substrate material in the pressing step is substantially equal to the volume of the void formed in the void forming step. The method of manufacturing a circuit-formed substrate described above has an effect that the shape, quantity, and the like of void formation that can maximize the effects of the present invention can be easily determined.

[0033] The invention according to claim 22 of the present invention is that the sheet-like reinforcing material is cut out at one or more places to form voids and then impregnated with a thermosetting resin to form a B-stage. A circuit-forming substrate material characterized in that a reinforcing material is impregnated with a thermosetting resin to form a B-stage, and then a portion thereof is cut out at one or more locations to form a void. The effect of easily making the plate thickness uniform or securing the compressibility and the interlayer connection reliability can be realized without making a significant change in the manufacturing process.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a process sectional view showing 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 aramid fibers 3 as shown in FIG.
The thermosetting resin 2 is not completely cured, but is in a so-called B-stage state including uncured components, and the substrate material 1 is usually called a prepreg. As the substrate material described in this embodiment, a material obtained by impregnating an aramid fiber nonwoven fabric with a thermosetting epoxy resin diluted with a solvent and then performing a B-stage through a slight heating and drying step can be used.

In order to fill the hole with the conductive paste accurately without causing the conductive paste to bleed or protrude in the vicinity of the penetrating or non-penetrating hole, the resin film 12 is peeled off from both sides of the substrate material 1. Laminate to

Next, as shown in FIG. 1B, a laser 4 is irradiated onto the resinous film 12 and the substrate material 1 to form a through hole 5.

Next, as shown in FIG. 1C, the conductive paste 6 is filled in the through holes 5 by means such as printing.

Next, as shown in FIG. 1D, a circular void 7 is formed in the substrate material 1. Various methods such as mechanical punching with a mold punch that can be easily in-lined and processing with an energy beam such as a laser can be used for forming the gap 7. Here, the voids 7 are small gaps when the aramid fibers 3 are impregnated with the thermosetting resin 2 or B-staged, that is, when the substrate material 1 is supplied in the prepreg state. (Not shown), it is formed after the prepreg state.

Next, as shown in FIG. 1 (e), after the resinous film 12 is peeled off, the substrate material 1 is sandwiched between the metal foils 8a and 8b, and heated by using a hot press (not shown). Press. The thermosetting resin 2 is melted and molded by heating and pressing, and then thermoset. At this time, as indicated by the arrow in FIG. 1F, the thermosetting resin 2 protrudes into the peripheral portion of the substrate material 1 and flows into the gap portion 7 so that the substrate material 1 is compressed in the thickness direction. . If there is no gap 7, the peripheral part is naturally thin and the central part is formed into a thick shape. This is because the flow resistance for the thermosetting resin 1 near the center to flow in the peripheral direction is much larger than when the thermosetting resin 2 near the periphery flows out of the substrate material 1. Although the above-mentioned void portion is related to this compression action, the factor caused by the flow into the peripheral portion or the void portion 7 is a larger and more dominant factor in terms of volume. In the figure, the void 7 is completely filled with the thermosetting resin 2, but it is not necessary to completely fill the void 7 when it is a part that is not used as a final product. After the molding, the metal foil 8a and the metal foil 8b are electrically connected by the conductive paste 6 into a shape as shown in FIG. The resistance value of the connection by the conductive paste 6 and its reliability are closely related to the amount of compression at the time of the heating and pressurization described above. In order to obtain a uniform connection resistance within the substrate, a uniform connection resistance as in the present embodiment is used. It goes without saying that a production method capable of obtaining a good compression is preferable. Next, the peripheral portion is cut into a desired size, and the metal foil 8 is patterned into a desired shape to form a circuit 9, thereby obtaining a double-sided circuit forming substrate as shown in FIG.

The operation of the present embodiment is prominent when a nonwoven fabric is used as a reinforcing material as described above. This is because in a glass fiber woven fabric used for a general glass epoxy substrate, since the fibers are regularly present in the XY directions, the resistance of the resin flowing inside the woven fabric at the time of heating and pressing is low, so that thickness variation does not easily occur. However, in the case of a nonwoven fabric, the resistance of the resin to flow inside the nonwoven fabric is considerably high, and thickness variation easily occurs.

In this embodiment, the double-sided circuit forming substrate has been described. However, it is needless to say that a multilayer circuit forming substrate can be obtained by repeating the steps a plurality of times.

Further, the present invention can be applied to the manufacture of a circuit forming substrate using a film-shaped B-stage material without a reinforcing material.

Also, for a circuit-forming substrate not using a conductive paste, the effect of making the substrate thickness uniform according to the present invention is effective for securing high-frequency characteristics of the substrate or in particular for applications requiring thickness accuracy. Become.

Further, the size of the metal foil 8 causes a problem that when the thermosetting resin 2 flows out to the peripheral portion and reaches the outside of the metal foil 8, it adheres to an intermediate plate or the like used in the hot pressing step. Although it is slightly larger than the size of the substrate material 1, there is a demand to reduce the margin as much as possible because the loss does not become a product substrate, and the effect of the present invention is to reduce the amount of flow to the peripheral portion. Alternatively, since the metal foil 8 can be made uniform, the size of the metal foil 8 can be made closer to the substrate material 1 to reduce the loss and reduce the cost of the metal foil 8.

In the present embodiment, the step of forming the gap 7 is performed after the filling of the conductive paste to prevent the conductive paste from dropping in the hole so as to minimize the influence of moisture absorption on the gap 7. It was performed before peeling the resinous film,
In order to increase productivity, it is also possible to form a gap with a laser when processing a through hole.

(Embodiment 2) FIG. 2 is a process sectional view showing a method of manufacturing a circuit forming substrate according to a second embodiment of the present invention.

As shown in FIG. 2A, a prepreg 1 in which a through hole is formed, a conductive paste 6 is filled, and a void 7 is formed is prepared as a part of the substrate material. Next, as shown in FIG. 2B, the metal foil 8, the prepreg described above and the two-layer core circuit forming substrate 10 are stacked and arranged to obtain a substrate material. At that time, positioning or temporary fixing between the materials is performed as necessary.

Next, the substrate material is compressed by a hot press to form a laminate as shown in FIG. Further FIG.
As shown in (d), the end face is cut at a predetermined position, and the surface metal foil 8 is patterned by a method such as etching to form a circuit 9, thereby obtaining a four-layer circuit forming substrate.

(Embodiment 3) FIG. 3 is a sectional view showing a circuit forming substrate material according to a third embodiment of the present invention. The substrate material 1 is a prepreg which is a composite material of the thermosetting resin 2 and the aramid fiber 3, and has the same properties as the substrate material 1 shown in the first embodiment. However, the gap 7 has already been formed in this state.

Regarding the formation of the voids 7, processing is performed in the state of an aramid fiber nonwoven fabric before impregnation of the thermosetting resin 2.
Alternatively, various methods such as processing after the prepreg state is obtained are possible, and laser or mechanical punching such as punching can be used as a processing tool.

In this embodiment, since the gap 7 is formed when the substrate material 1 is supplied, a high-quality circuit can be provided without adding a process for machining the gap during the manufacture of the circuit forming substrate. This makes it possible to manufacture a formed substrate. However, when a process such as printing of a conductive paste as described in the first embodiment is included in the manufacturing process, there may be a case where a void portion becomes a problem. In that case, the formation of a void portion may be included in the process as in the first embodiment.

[0053]

As described above, the method for manufacturing a circuit-forming substrate and the substrate material according to the present invention use the substrate material when manufacturing a circuit-forming substrate using a substrate material composed of a single material or a plurality of materials. Including a pressing step to compress in the thickness direction,
A manufacturing method having a void forming step of hollowing out a part of the substrate material at one place or a plurality of places before the pressing step, or impregnating a sheet-like reinforcing material with a thermosetting resin to form a B-stage and then a part thereof. By using a substrate material in which voids are formed by hollowing out one or more locations, a circuit-formed substrate can be manufactured without causing variations in the thickness of the substrate material by press working, and as a result, a highly reliable circuit It can provide a formation substrate.

[Brief description of the drawings]

FIG. 1 is a process cross-sectional view of a method of manufacturing a circuit formation substrate according to a first embodiment of the present invention.

FIG. 2 is a process cross-sectional view of a method for manufacturing a circuit formation substrate according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a circuit forming substrate material according to a third embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 substrate material 2 thermosetting resin 3 aramid fiber 4 laser 5 through hole 6 conductive paste 7 void 8 metal foil 9 circuit 10 core circuit forming substrate 12 resin film

Claims (22)

[Claims] When manufacturing a circuit forming substrate using a substrate material composed of a single material or a plurality of materials, the method includes a pressing step of compressing the substrate material in a thickness direction. A method for manufacturing a circuit-forming substrate, comprising: a step of forming a gap for partially cutting out a material. 2. The method according to claim 1, further comprising a step of forming a plurality of voids in a part of the substrate material. 3. The method according to claim 1, wherein the gap has a circular shape. 4. The method for producing a circuit-formed substrate according to claim 1, wherein the pressing step is pressurization accompanied by heating, and is a so-called hot press in which the substrate material is melted, molded, and then thermally cured. . 5. The method according to claim 1, wherein the gap is formed by using laser processing. 6. The method according to claim 1, wherein the voids are formed by punching using a die punch. 7. A substrate material comprising a prepreg or B-stage resin sheet and a metal foil disposed on both sides or one surface of the prepreg or B-stage resin sheet, wherein a void is formed in the prepreg or B-stage resin sheet. The method for manufacturing a circuit-formed substrate according to claim 1. 8. A laminate comprising a core circuit-forming substrate, a prepreg or a B-stage resin sheet disposed on one or both sides of the core circuit-forming substrate, and a metal foil disposed on both sides or one side of the laminate. 2. The method according to claim 1, wherein a gap is formed in one or more of the circuit forming substrate, the prepreg, and the B-stage resin sheet. 9. The method according to claim 1, further comprising a hole forming step of forming a penetrating or non-penetrating hole in the substrate material before the pressing step, and a filling step of filling the penetrating or non-penetrating hole with a conductive paste. A method for manufacturing a circuit-formed substrate according to claim 1. 10. The method according to claim 9, wherein voids are formed at positions other than through holes or non-through holes filled with a conductive paste. 11. A method of laminating a resin film on a substrate material before a hole forming step of forming a through or non-through hole and a filling step of filling a conductive paste into the through or non-through hole. The method for manufacturing a circuit-formed substrate according to claim 9, further comprising a step of peeling the resinous film from the substrate material. 12. The method according to claim 9, further comprising a void forming step after the filling step of filling the conductive paste into the through or non-through holes. 13. The method for manufacturing a circuit-formed substrate according to claim 9, further comprising a step of forming a gap before the step of filling a conductive paste into a hole penetrating or not penetrating the substrate material. 14. The method according to claim 9, further comprising the step of forming a gap in the step of forming a through hole or a non-through hole in the substrate material. 15. The method according to claim 11, further comprising a step of forming a gap after the step of laminating the resinous film on the substrate material. 16. The method according to claim 11, further comprising a gap forming step between a filling step of filling the conductive paste into the through holes or the non-penetrating holes and a step of peeling the resinous film from the substrate material. A method for manufacturing a circuit-formed substrate. 17. The method according to claim 7, wherein the reinforcing material of the prepreg is made of a non-woven fabric. 18. The circuit forming method according to claim 2, wherein the number or volume of the voids formed in the void forming step differs between the central portion and the peripheral portion of the substrate material as the amount per unit area of the substrate material. Substrate manufacturing method. 19. The circuit forming substrate according to claim 18, wherein the number or volume of the voids formed in the void forming step in the central portion of the substrate material is larger than the peripheral portion in terms of the amount per unit area. Manufacturing method. 20. The circuit-forming substrate according to claim 18, wherein the number or volume of the voids formed in the void forming step in the peripheral portion of the substrate material is larger than the central portion in terms of the amount per unit area. Manufacturing method. 21. The method according to claim 1, wherein the amount of the substrate material component flowing around the substrate material in the pressing step is substantially equal to the volume of the void formed in the void forming step. 22. One or more portions of the sheet-like reinforcing material are cut out to form voids and then impregnated with a thermosetting resin to form a B-stage, or the sheet-like reinforcing material is impregnated with a thermosetting resin. A circuit-forming substrate material, wherein a part of the circuit-forming substrate material is hollowed out at one or more locations after the B-stage.