JPH0521960A - Multilayer printed wiring board and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Object] To obtain a highly reliable multilayer printed wiring board and a simple manufacturing method thereof by reducing the number of through holes such as through holes and via holes. [Structure] A plurality of substrates, each having a circuit pattern and a land for connection formed on opposite surfaces thereof, are laminated so as to sandwich an anisotropic conductive sheet with the opposing portions of the circuit pattern covered with a resist. The through holes provided in the sheet are filled with an adhesive and adhered. Since the anisotropic conductive sheet has conductivity only in the thickness direction and does not have conductivity in the plane direction, opposing lands are electrically connected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a conventional multilayer printed wiring board. In the figure, 1 is a multilayer printed wiring board,
Reference numerals 2 and 3 denote outer layer boards constituting the multilayer printed wiring board 1, 4 denotes an inner layer board sandwiched between the outer layer boards 2 and 3, and 5 denotes a first layer circuit pattern, which is formed on the surface of the outer layer board 2. 6 and 7 are second
Layers and third layer circuit patterns are formed on both sides of the inner layer board 4. A fourth layer circuit pattern 8 is formed on the surface of the outer layer plate 3. Reference numeral 9 is a through hole penetrating the outer layer plates 2 and 3 and the inner layer plate 4, and has a through hole plated portion 9a for connecting the lands 5a to 8a formed in the first to fourth layer circuit patterns 5 to 8. Reference numeral 10 denotes a via hole, which has a through hole plated portion 10a which penetrates the inner layer plate 4 and connects the lands 6b and 7b formed on the second and third layer circuit patterns 6 and 7.

The above-mentioned multilayer printed wiring board 1 is manufactured as follows. First, by forming a resist pattern on a copper clad laminate having copper foils on both sides of an insulating substrate such as a glass fiber / epoxy resin composite material and performing etching,
Second layer and third layer circuit patterns 6 and 7 are formed. Then, the lands 6b and 7b are drilled to form the through-hole plated portion 1
After forming the via hole 10 by forming 0a, a prepreg and a copper foil are laminated on both surfaces and heat-pressed to form a copper-clad multilayer laminate. A resist pattern is formed on this copper-clad multilayer laminate and etching is performed to form the first layer and fourth layer circuit patterns 5 and 8. After that, the through holes 9 are formed by making holes in the lands 5a to 8a to form the through hole plated portions 9a, and the multilayer printed wiring board 1 is completed.

The above-mentioned multilayer printed wiring board 1 is used by mounting components in the through holes 9.

[0005]

However, in the conventional multilayer printed wiring board 1 as described above, many through holes such as the through holes 9 and the via holes 10 are formed, so that the reliability is insufficient. was there. That is, the above-mentioned through hole 9 is mainly used for mounting components.
The via hole 10 is formed mainly for the purpose of connecting the upper and lower circuit patterns, but in both cases, it is necessary to perform plating after the drilling to connect the lands, and the more these through holes, the lower the plating reliability.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to reduce the number of through holes such as through holes and via holes to improve reliability. And a method for manufacturing the same.

[0007]

The present invention is the following multilayer printed wiring board and method for manufacturing the same. (1) A plurality of substrates having circuit patterns on opposing surfaces, connecting lands formed on opposing portions of each substrate so as to connect to the respective circuit patterns, and lands on the opposing surfaces stacked between the substrates. An anisotropic conductive sheet for electrically connecting, a fixing material for fixing the opposing substrate in a state of being pressure-bonded to the anisotropic conductive sheet, and a resist formed on the opposing portion of the circuit pattern of each substrate, A multilayer printed wiring board, wherein the anisotropic conductive sheet has conductivity only in the thickness direction and does not have conductivity in the plane direction. (2) An anisotropic conductive sheet in which a circuit pattern and a land are formed on the facing surface, and through holes are formed in a portion other than the portion corresponding to the land between a plurality of substrates in which a resist is formed in the facing portion of the circuit pattern. The above-mentioned (1), in which the lands are sandwiched, the through holes are filled with an adhesive, the adhesive is cured in a state where the substrates are pressed to bond the substrates, and the lands are electrically connected to each other. For manufacturing a multilayer printed wiring board.

[0008]

According to the multilayer printed wiring board of the present invention, a circuit pattern and a land are formed on the opposing surfaces, and a plurality of substrates having a resist formed on the opposing portions of the circuit pattern are provided.
Stack the anisotropic conductive sheets with through holes formed in the parts other than the parts corresponding to the lands so as to sandwich them, fill the through holes with an adhesive, and cure the adhesive while pressing the substrate. It is manufactured by bonding the substrates and electrically connecting the lands.

In the multilayer printed wiring board manufactured as described above, since the anisotropic conductive sheet has conductivity only in the thickness direction and does not have conductivity in the plane direction, the anisotropic conductive sheet is formed on the opposing portion of each substrate. The formed lands are electrically connected by the anisotropic conductive sheet. Further, since the opposing portion of the circuit pattern is blocked by the resist, no electrical connection is made. Therefore, through holes such as through holes and via holes for connecting the facing surfaces of the respective substrates are not required, the number of through holes is reduced, and reliability is improved.

In the method for manufacturing a multilayer printed wiring board according to the present invention, the through holes are formed in the anisotropic conductive sheet, the adhesive is filled therein, and the adhesive is laminated between the substrates to cure the adhesive under pressure. Since it is manufactured by, it becomes unnecessary to stack and harden the prepreg for land connection on the opposite surface and to form through holes such as through holes and via holes.
The manufacturing process is simplified and the yield is improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a multilayer printed wiring board according to an embodiment,
FIG. 2 is an exploded perspective view thereof, in which the same reference numerals as those in FIG. 3 denote the same or corresponding portions.

Reference numerals 11 and 12 denote substrates which will be the outer layer plates 2 and 3, respectively. First and second layer circuit patterns 5, 6 and lands 5a, 6a, 6c are formed on both surfaces of the substrate 11,
The lands 5a and 6a are connected by a through hole plated portion 10a formed in the via hole 10. Board 1
On both sides of 2, the third and fourth layer circuit patterns 7, 8
And the land 7c is formed. Land 6c, 7c
Are formed on opposing portions of the substrates 11 and 12.

Reference numeral 13 is an anisotropic conductive sheet which becomes the inner layer plate 4. The anisotropic conductive sheet 13 is a sheet in which conductive needles are oriented in the thickness direction and the needles are insulated from each other. The anisotropic conductive sheet 13 has conductivity only in the thickness direction and has conductivity in the plane direction. The sheet does not have. The anisotropic conductive sheet 13 has through holes 14 in portions other than the portions corresponding to the lands 6c and 7c, and the through holes 14 are filled with an adhesive agent 15.
1 and 12 are fixed to the anisotropic conductive sheet 13 in a pressure-bonded state. Reference numeral 16 is a resist formed on the opposing portions of the circuit patterns 6 and 7.

The above-mentioned multilayer printed wiring board 1 is manufactured as follows. First, the circuit pattern 5, on the substrates 11 and 12,
6 and 7, 8 are formed, and the circuit pattern 6,
After the lands 6c and 7c are formed on the opposing portions of the substrates 11 and 12 so as to be connected to the substrate 7, the substrate 11 is perforated and through-hole plated to form the through-hole plated portion 10a.
Forming a via hole 10 having Via holes are also formed in the substrate 12 in the same manner, but the illustration is omitted.

After that, the circuit patterns 6 on the substrates 11 and 12,
A resist 16 is formed so as to cover the facing portion of 7. The resist 16 is formed on the entire surfaces of the opposing surfaces of the substrates 11 and 12 except the portions corresponding to the lands 6c and 7c and the through holes 14.
It is formed by silk printing.

On the other hand, the land 6 of the anisotropic conductive sheet 13
Through holes 14 are formed in a portion other than the portions corresponding to c and 7c, and this anisotropic conductive sheet 13 is laminated on the substrate 12,
A thermosetting adhesive 1 is applied to the through hole 14 by silk printing or the like.
Fill 5. After that, the substrate 1 is placed on the anisotropic conductive sheet 13.
1 is laminated and the substrates 11 and 12 are pressed under heat by a hot press to cure the adhesive 15. As a result, the substrates 11 and 12 are adhered in a state where the anisotropic conductive sheet 13 is pressure-bonded, the lands 6c and 7c are electrically connected by the anisotropic conductive sheet 13, and the multilayer printed wiring board 1 is manufactured.

In the multilayer printed wiring board 1 manufactured as described above, the anisotropic conductive sheet 13 has conductivity only in the thickness direction, and does not have conductivity in the plane direction. The lands 6c and 7c formed on the facing portions of the circuit patterns 6 and 7 formed on the facing surfaces are electrically connected by the anisotropic conductive sheet 13. Further, since the opposing portions of the circuit patterns 6 and 7 are blocked by the resist 16, no electrical connection is made. Therefore, each substrate 11, 1
Through holes (via holes) are not required for connecting the two facing surfaces, the number of through holes is reduced, and reliability is increased.

Also, in this embodiment, the anisotropic conductive sheet 1 is used.
Since the through holes 14 are formed in 3 and the adhesive 15 is filled and fixed in the through holes 14, the through holes 14 are uniformly formed on the entire surface of the anisotropic conductive sheet 13, and the whole is made uniform. ,
And it can be easily fixed, but it may be fixed by other fixing means.

Further, the resist 16 is a circuit pattern 6, 7
Since it is formed so as to cover the surface of, it can be formed easily and completely, but it may be formed by another method. For example, the through holes 14 are formed in the anisotropic conductive sheet 13 in the portions corresponding to the opposing portions of the circuit patterns 6 and 7, and the adhesive 15 is filled and bonded, so that the adhesive 15 can also be used as a resist. You can

In the method for manufacturing the multilayer printed wiring board 1 described above, the through holes 14 are formed in the anisotropic conductive sheet 13, the adhesive 15 is filled therein, and the substrates 11 and 12 are laminated and bonded under pressure. Since it is manufactured by curing the agent 15, it is not necessary to stack and harden the prepreg for connecting the lands 6c and 7c on the facing surface, and to form a through hole (via hole), and the manufacturing process is simplified.

In the above embodiment, the anisotropic conductive sheet 13 is used.
After stacking, the adhesive 15 is filled, but the reverse is also possible.
In this case, the adhesive 15 is formed on the substrate 12 by silk printing or the like, then the anisotropic conductive sheet 13 is laminated, and the through hole 14 is filled with the adhesive 15.

Although the above description does not show a through hole penetrating the entire multilayer printed wiring board 1,
It is possible to form another via hole 10 when connecting the circuit pattern other than the facing surface, for example, when connecting the first layer circuit pattern 5 and the fourth layer circuit pattern 8 or to form the through hole 9 for component mounting as in the conventional case. It is the same. Further, in the above embodiment, the case where two substrates are laminated has been described, but it is also possible to laminate a larger number of substrates in the same manner.

[0023]

According to the multilayer printed wiring board of the present invention, the lands formed on the opposing portions of the substrate so as to be connected to the circuit pattern are electrically connected by the anisotropic conductive sheet. The number of through holes such as through holes and via holes is reduced, and reliability is improved.

According to the manufacturing method of the present invention, since the through holes formed in the anisotropic conductive sheet are filled with the adhesive to bond the substrate, the above-mentioned excellent multilayer printed wiring board can be easily manufactured. Can be manufactured in various processes,
Since the number of through hole forming processes is reduced, the yield is also improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multilayer printed wiring board according to an example.

FIG. 2 is an exploded perspective view of a multilayer printed wiring board according to an embodiment.

FIG. 3 is a cross-sectional view of a conventional multilayer printed wiring board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Multilayer printed wiring board 2, 3 Outer layer board 4 Inner layer board 5-8 Circuit patterns 5a, 6a, 6b, 6c, 7a, 7b, 7c, 8a Land 9 Through hole 10 Via hole 11, 12 Substrate 13 Anisotropic conductive sheet 14 Through Hole 15 Adhesive 16 Resist

Claims (2)

[Claims] 1. A plurality of substrates having circuit patterns on opposing surfaces, connection lands formed on opposing portions of each substrate so as to be connected to the respective circuit patterns, and laminated between the substrates and opposing surfaces. An anisotropic conductive sheet for electrically connecting the lands, a fixing material for fixing the opposing substrate to the anisotropic conductive sheet in a pressure-bonded state, and a resist formed on the opposing portion of the circuit pattern of each substrate. The anisotropic conductive sheet has conductivity only in the thickness direction,
A multilayer printed wiring board comprising a sheet having no in-plane conductivity. 2. Anisotropy in which a circuit pattern and a land are formed on the opposing surface, and a through hole is formed in a portion other than the portion corresponding to the land between a plurality of substrates having a resist formed on the opposing portion of the circuit pattern. It is characterized in that the conductive sheets are laminated so as to be sandwiched, the through holes are filled with an adhesive, and the adhesive is cured by pressing the substrates to bond the substrates to each other and electrically connect the lands. The method for manufacturing a multilayer printed wiring board according to claim 1.