JP2002141669A - Base material for inter-substrate connection and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base material for inter-substrate connection which joins circuit boards together by a simple structure and gives electric continuity between the circuit boards. SOLUTION: This base material 3 for inter-substrate connection which is interposed between the 1st and 2nd circuit boards 1 and 2 to electrically connect the both to each other is provided with a conductive path formed by burying a conductive material 40 in a base material 8 for adhesion. This conductive path 4 is formed by laminating the conductive material 40 on the base material 8 for adhesion, forming a punch hole by punching specific parts of the conductive material 40 and base material 8 for adhesion with a die cutting punch, and receiving a punching of the conductive material and a punching of the base material for adhesion by an imbedding punch, then lifting the embedding punch, and embedding the punching of the conductive material in the punched hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for connecting between substrates for interposing between circuit boards and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in manufacturing a multilayer printed wiring board, there is a method in which first and second circuit boards having a conductive circuit are prepared, and a prepreg is interposed between the circuit boards and laminated and pressed. In conducting electric conduction between the first and second circuit boards, a through-hole penetrating through the first and second circuit boards and the prepreg therebetween is drilled, and metal plating is performed therein. In order to effectively use the prepreg for bonding between the first and second circuit boards, the inventor has not only provided the prepreg with a function as an adhesive for bonding between the circuit boards, but also provided an electrical connection between the two circuit boards. I thought of giving roles to perform.

[0003]

SUMMARY OF THE INVENTION The present invention aims to provide a substrate for connection between boards which can join circuit boards by a simple structure and can conduct electricity between circuit boards, and a method of manufacturing the same. is there.

[0004]

According to a first aspect of the present invention, there is provided a base material for inter-substrate connection between a first circuit board and a second circuit board for performing adhesion and electrical conduction between the first and second circuit boards. The substrate for connection between substrates is a substrate for connection between substrates, wherein a conductive path formed by embedding a conductive material in a substrate for adhesion is provided.

[0005] The substrate for connection between the substrates of the present invention is a conductive material for electrical conduction between the first and second circuit boards, which is used for bonding between the first and second circuit boards. A road is formed. Therefore, by laminating the first and second circuit boards above and below the bonding substrate, the substrate-to-substrate connecting substrate can perform both bonding and conduction between the circuit boards. Therefore, according to the present invention, both adhesion and electrical conduction between the first and second circuit boards can be performed with a simple structure.

It is preferable that at least the upper and lower ends of the conductive material are made of a low melting point conductive material. As a result, the bonding base material is strongly bonded to the conductor circuits of the first and second circuit boards, and the conductivity of the conductive path is increased. The low-melting-point conductive material is a conductive material whose melting point is lower than the temperature at which the base material for connecting the substrates is interposed between the first and second circuit boards and these are heated and pressed. Solder, conductive adhesive, etc. The conductive adhesive is obtained by adding metal particles to a resin.

A low melting point conductive material may be provided only at the upper and lower ends of the conductive material, and a high melting point conductive material having a higher melting point than the low melting point conductive material may be provided at other portions (for example, at the center). Examples of the high melting point conductive material include copper, aluminum, and nickel. Also, all of the conductive materials
The low melting point conductive material may be used.

It is preferable to use a prepreg in which an insulating resin is impregnated in a glass cloth as the bonding substrate. Thereby, the first and second circuit boards can be firmly bonded.

As the insulating resin, epoxy resin, phenol resin, bismaleimidetreazine resin,
Thermosetting resins such as polyphenylene resin, polyphenylene ether resin, and polyimide resin, or a mixture thereof can be used. The bonding substrate may include a reinforcing material such as a glass cloth or an inorganic filler.

The above-mentioned glass cloth is made by weaving fiber bundles of glass fibers in two directions, an X direction and a Y direction orthogonal to the X direction. The adhesive base material may have a property of contracting upon curing depending on the type of resin.
In this case, it is preferable to control the size of the bonding base material in order to prevent the conductive paths from being displaced.

Specifically, the difference between the volume of the fibers arranged in the X direction and the volume of the fibers arranged in the Y direction is preferably 5% by volume or less. If it exceeds 5% by volume,
This is because the shrinkage rate of the bonding base material differs between the X direction and the Y direction, and the conductive paths may be displaced. Further, it is preferable to use the same fiber diameter in the X direction and the Y direction. Further, it is preferable that the fiber diameter is small. As a result, the bonding area with the insulating resin can be made the same,
The bonding area can be increased.

As another method of controlling the size, there is a method of adding 30 to 80% by weight of an inorganic filler to an adhesive substrate. If the amount is less than 30% by weight, the bonding substrate XY
There is a possibility that the shrinkage in the directions may be significantly different. 80% by weight
If the ratio exceeds the above range, the adhesive strength of the adhesive substrate may decrease.

The first circuit board and the second circuit board have, for example, a conductor circuit, and a part of the conductor circuit is joined to upper and lower ends of the conductive path. The first and second circuit boards are electrically connected through the conductive path. It is preferable that a connection pad is provided at a portion of the conductive circuit that is connected to the conductive path. Thereby, the conductivity between the conductive path and the conductive circuit can be improved. The connection pad covers part or all of the upper and lower ends of the conductive path, but preferably covers the entirety. This gives
Electrical connection between the conductive path and the connection pad is ensured. The conductor circuit includes a land, a via hole, a wiring pattern, and the like.

It is preferable that an electronic component is mounted on a surface of the first circuit board and / or the second circuit board on a side facing the inter-substrate connection base material. Thereby, high-density mounting of components can be realized.
Examples of the electronic component include a chip capacitor, an electrolytic capacitor, and a chip resistor. Of course, an electronic component may be mounted on the surface of the first circuit board and / or the second circuit board opposite to the side facing the inter-substrate connection base material.

According to a third aspect of the present invention, there is provided a board for connecting between the first and second circuit boards, the board having a conductive path for electrical conduction between the first and second circuit boards. In the method of manufacturing a material, in forming the conductive path, a bonding material and a conductive material are laminated, and a predetermined portion of the conductive material and the bonding material is punched out with a punch to form a punched hole. Forming and receiving the punched piece of the bonding base material and the punched piece of the conductive material with an embedding punch, and then bringing the embedding punch close to the punched hole of the bonding base material to punch the conductive material. A method of manufacturing a base material for connection between substrates, comprising embedding a piece into the punched hole.

In the present manufacturing method, a punched punch and a punched piece are formed in the laminated bonding base material and the conductive material by pressing with a punch for punching, and the punched hole and the punched piece are subsequently formed. A punched piece of a conductive material is embedded in a punched hole of the bonding base material. As a result, a conductive path made of a punched piece of a conductive material is formed on the bonding substrate. By such a punching process, a conductive path can be easily formed.

The conductive material laminated on the bonding substrate is, for example, a conductive sheet having conductivity. Examples of the conductive sheet include a copper foil, a solder foil, a conductive film in which a metal powder is dispersed in a resin, and an anisotropic conductive film that exhibits conductivity when pressed. Further, it is preferable to use solder as the conductive material. This is because they are melted at a relatively low temperature and are easily fused to connection pads.

The ratio (A / B) of the thickness A of the conductive sheet to the thickness B of the bonding substrate is preferably 0.7 to 1.5. As a result, the thickness of the embedded conductive material becomes substantially the same as the length of the punched hole of the bonding substrate, and when the first and second circuit boards are laminated, the upper and lower ends of the conductive material are connected to these circuit boards. To the connection pad. For this reason, it is possible to form a multilayer printed wiring board having high conductive reliability. It is more preferable that the ratio (A / B) of the metal conductor that is easily melted be 0.7 to 1.2. If the ratio exceeds 1.2, the molten metal easily flows in the horizontal direction, and is easily connected to another adjacent electrode, which may cause a short circuit. On the other hand, in the case of a soft conductive material such as a resin film containing a conductive metal, the ratio (A / B) is preferably 1 to 1.5 because the material does not easily flow.

When the first and second circuit boards are laminated and pressure-bonded with the inter-substrate connecting base material interposed therebetween, at least one of the conductor circuits of the first and second circuit boards is placed on the upper and lower ends of the conductive path. It is preferable to heat with the parts in contact. As a result, the conductor circuit comes into close contact with the upper and lower ends of the conductive material at the time of thermocompression bonding. For this reason, the molten adhesive base material does not enter between the conductive material and the conductive circuit. Therefore, the conductive path and the conductor circuit can be reliably connected.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A substrate for connection between substrates and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the board-to-board connection base material 3 of this embodiment is provided between the first and second circuit boards 1 and 2 to perform adhesion and electrical conduction therebetween. The base material 3 for connection between boards is made of a base material 8 for bonding.
A conductive path 4 in which a conductive material 40 is embedded is provided.

A method of manufacturing the substrate 3 for connecting substrates will be described. First, a prepreg formed by impregnating a glass cloth with an epoxy resin is used as the bonding substrate 8. Next, the conductive path 4 is formed in the bonding substrate 8. In forming the conductive path 4, as shown in FIG.
A solder foil 400 for forming the conductive material 40 is laminated on the bonding base 8. The thickness of the bonding substrate 8 is 0.0
6 mm, the thickness of the solder foil 400 is 0.07 mm, and both are almost the same thickness. Next, these are placed on the die 7. The die 7 has a guide hole 70 at a portion corresponding to the conductive path forming portion of the bonding base material 8. The shape of the guide hole 70 is substantially the same as the cross-sectional shape perpendicular to the axial direction of the conductive path. An upper punch 81 for punching and a lower punch 82 for embedding are arranged at positions above and below the guide hole 70 so as to be vertically movable. In the stage before punching, the upper punch 81 is arranged above the die 7 and the lower punch 82 is arranged below the die.

Next, as shown in FIG. 2B, the upper punch 81 is moved downward, and the bonding base material 8 and the copper foil 400 placed on the die 7 are punched out in a circular shape. Then, punch holes 801 and 401 are formed. The bonding base material 8 formed by punching and the punched pieces 80 of the copper foil 400
2, 402 are received by the lower punch 82.

Next, as shown in FIG. 2C, the upper punch 81 is slid upward, and the lower surface thereof is returned to the level of the upper surface of the bonding base material 8. At the same time, the lower punch 82 is slid upward, and the punched piece 402 of the copper foil 400 placed thereon is embedded in the punched hole 801 of the bonding base material 8. Punched piece 4 of copper foil 400
02 of the bonding base material 8 disposed under the base material 02
2 remove. Thereby, the copper foil 4
The conductive path 4 is formed by embedding the conductive material 40 composed of the punched pieces 402 of 00. As described above, the substrate 3 for connecting between substrates is obtained.

As shown in FIG. 3, when the first and second circuit boards 1 and 2 are laminated with the inter-substrate connecting base material 3 interposed therebetween,
The multilayer printed wiring board 9 is obtained. The first and second circuit boards 1 and 2 have conductor circuits 51 and 52, respectively. The conductor circuit 51 provided on the first circuit board 1 has a wiring pattern 511 formed on the upper and lower surfaces of the insulating substrate 7 and a via hole 512. The wiring pattern 511 is connected to the connection pad 510. The conductor circuit 52 provided on the second circuit board 2 is
A wiring pattern 521 formed on the upper and lower surfaces of the insulating substrate 7;
And a via hole 522. The wiring pattern 521 is
It is connected to the connection pad 520.

On the surface of the first circuit board 1 on the side facing the bonding substrate 8, connection pads 510 to be joined to the upper and lower ends of the conductive path 4 are provided. Conductive path 4 and wiring pattern 5
Electrical connection with the connection pad 11 is made through the connection pad 510. On the surface of the second circuit board 2 on the side facing the bonding substrate 8, connection pads 520 are formed which are joined to the upper and lower ends of the conductive path 4. Conductive path 4 and wiring pattern 52
1 is conducted through the connection pad 520. An electronic component 6 such as an electrolytic capacitor is mounted on the surface of the second circuit board 2 on the side facing the bonding substrate 8. The insulating resin material 60 is filled in the via holes 512 and 522 provided in the first and second circuit boards 1 and 2.

In forming the first circuit board 1,
As shown in FIG. 1, a composite resin material such as glass cloth / bismaleimide triazine is prepared as an insulating substrate 7 for the first circuit board 1, and copper foils are adhered to both surfaces thereof. Then, by the subtraction method or the additive method,
The wiring pattern 511 is formed. At this time, connection pads 510 are formed in portions of the insulating substrate 7 corresponding to the conductive paths 4. In addition, a hole is formed in the insulating substrate 7 with a drill or the like, and plating is applied to the inner wall to impart conductivity, thereby forming a via hole 512. The insulating resin material 60 is filled in the via hole 512. Further, an electronic component 6 such as an electrolytic capacitor is joined to a side of the insulating substrate 7 corresponding to the bonding substrate 8. Thereby, the first circuit board 1 is obtained.

In forming the second circuit board 2,
Similarly to the first circuit board, a wiring pattern 521 is formed on the insulating substrate 7 for the second circuit board 2. At this time, a connection pad 5 is provided on a portion of the insulating substrate 7 corresponding to the conductive path 4.
20 is formed. Also, a via hole 522 is formed in the insulating substrate 7.
To form Thereby, the second circuit board 2 is obtained.

In forming a multi-layer printed wiring board with the inter-substrate connecting substrate 3 interposed between the first and second circuit boards 1 and 2, as shown in FIG. Two circuit board 2, base material for connection between boards 3, first circuit board 1,
The inter-substrate connection base material 3 and the second circuit board 2 are stacked and pressed at 4 MPa in the thickness direction. As a result, the connection pads 5, which are a part of the conductor circuits formed on the first and second circuit boards 1 and 2, are provided on the upper and lower ends of the conductive paths 4 in the substrate 3 for connecting substrates.
10,520 contact. In this state,
Heat at ° C. Then, the bonding substrate 8 in the substrate-to-substrate connecting substrate 3 is welded to the first and second circuit boards 1 and 2. Thereafter, when heating is stopped, the bonding base material 8 is cured. As described above, the multilayer printed wiring board 9 shown in FIG.
Is obtained.

The inter-substrate connection base material 3 of this embodiment is obtained by forming the conductive path 4 on the bonding base material 8 and has a role not only as a substrate adhesive but also as an electric conductive path. I have. Therefore, by interposing the substrate 3 for connection between the substrates between the first and second circuit boards 1 and 2, both the substrate bonding and the electrical conduction can be performed. Further, since connection pads 510 and 520 are arranged at the upper and lower ends of the conductive path 4,
Electrical conduction to the conductor circuits 51 and 52 provided on the first and second circuit boards 1 and 2 can be reliably performed through the connection pads. In addition, a multilayer substrate can be obtained by performing a single lamination. In this example, one second circuit board 2 is laminated on each of the upper and lower sides of the first circuit board 1. However, the second circuit board 2 may be laminated on only one side, or two or more second circuit boards may be laminated. Good.

Embodiment 2 In this embodiment, as shown in FIG. 4, the upper and lower ends of a conductive material 40 embedded in a bonding base material 8 are made of a low-melting-point conductive material layer 41.
Other portions are made of the high melting point conductive material layer 42. The low melting point conductive material layer 41 is made of solder, and the high melting point conductive material layer 42 is made of copper. In forming the above-mentioned conductive material, as shown in FIG. 5, a solder layer as a low-melting conductive material layer 41 is formed on both upper and lower sides of a copper foil as a high-melting conductive material layer. The solder layer is formed by a plating method or by sticking a solder foil. The conductive material 40 is superimposed on the bonding substrate 8 and then placed on the die 7 in the same manner as in the first embodiment.
The first and the lower punches 82 are used for punching, and a punched piece of the conductive material 40 is embedded in the bonding base material 8.

In this embodiment, since the low-melting-point conductive material 41 is disposed at the upper and lower ends of the conductive material 40, the first and second circuit boards are stacked on the upper and lower sides of the conductive material 41, and when the heat-compression bonding is carried out, The upper and lower parts are melted and firmly joined to the connection pad. Therefore, the conductivity between the conductive material 40 and the conductive circuit is increased.

Embodiment 3 In this embodiment, as shown in FIG. 6, via holes 512 and 522 are arranged above and below a conductive path 4 of a substrate 3 for connection between substrates, and the via hole 512, the conductive path 4 and the via hole 522 are continuous. This is an example in which one through hole 5 is formed. The inner walls of the via holes 512 and 522 are covered with the metal plating film 50 and are connected to lands 501 formed in the upper and lower openings. The inside of the via holes 512 and 522 is filled with the insulating resin material 60. The conductive path 4 is joined to the lands 501 of the via holes 512 and 522.

In this embodiment, the conductive path 4 of the substrate 3 for connecting substrates is used as the middle layer of the through hole 5. Also in this case, the conductive path 4 can be joined to the upper and lower lands 501 to enhance the conductivity of the through hole 5.
In addition, instead of providing the metal plating film on the inner walls of the via holes 512 and 522 and the insulating resin material 60 therein, instead of filling the entire inside of the via holes 512 and 522 with a conductive material, the conductive material 40 becomes conductive in the via holes. Bonding to conductive materials. In this case, lands need not be provided in the via holes.

[0034]

According to the present invention, it is possible to provide a substrate for connection between substrates, which can join circuit substrates with a simple structure and can conduct electricity between the circuit substrates, and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a substrate for connection between substrates in a first embodiment.

FIG. 2 is an explanatory diagram of a method for manufacturing a substrate for connection between substrates according to the first embodiment.

FIG. 3 is a cross-sectional view of the multilayer printed wiring board according to the first embodiment.

FIG. 4 is a cross-sectional view of an inter-substrate connection base material according to a second embodiment.

FIG. 5 is an explanatory diagram of a method of manufacturing a substrate for connection between substrates in a second embodiment.

FIG. 6 is a sectional view of a multilayer printed wiring board according to a third embodiment.

[Explanation of symbols]

 1. . . 1. first circuit board; . . 2. second circuit board; . . Base material for connection between substrates, 301, 401, 70. . . Holes, 302, 402. . . 3. punched pieces; . . Conductive path, 40. . . Conductive material, 41. . . 42. low melting point conductive material layer; . . High melting point conductive material layer, 400. . . Copper foil, 51, 52. . . Conductor circuit, 510, 520. . . Connection pads, 511, 521. . . Wiring pattern, 512, 522. . . Via hole, 6. . . Electronic components, 60. . . 6. Insulating resin material, . . Die, 8. . . Base material for bonding, 81. . . Upper punch, 82. . . Lower punch, 9. . . Multilayer printed wiring board,

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/40 H05K 3/40 K

Claims (3)

[Claims] An inter-substrate connection base material provided between a first circuit board and a second circuit board to perform adhesion and electrical conduction between the first and second circuit boards. A substrate for connection between substrates, wherein a conductive path formed by embedding a conductive material in an adhesive substrate is provided. 2. The base material for connection between substrates according to claim 1, wherein at least upper and lower ends of the conductive material are made of a low melting point conductive material. 3. A method of manufacturing a substrate for connecting between substrates, having a conductive path for establishing electrical continuity between the first and second circuit boards, and bonding the first and second circuit boards together. In forming the conductive path, a bonding material and a conductive material are laminated, and a predetermined portion of the conductive material and the bonding material is punched by a punch to form a punched hole. The punched piece of the bonding base material and the punched piece of the conductive material are received by the embedding punch, and then the embedding punch is brought close to the punched hole of the bonding base material. A method for producing a substrate for connection between substrates, characterized by being embedded in a substrate.