JPH11112150A - Multilayered substrate and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive multilayered substrate which has a simple constitution and can increase the packaging density. SOLUTION: A multilayered substrate comprises a first wiring board 10 having a first wiring pattern 11 formed of a conductor such as copper foil, etc., and a second wiring board 20 having a second wiring pattern 11 formed of copper foil, etc., and to be electrically conducted to the first wiring board 10. Protrusions 15 formed of conductor paste containing copper or silver are partially provided at prescribed spots of the first wiring pattern 11 to be conducted electrically to the second wiring pattern 11, and anisotropic conductors 22 having conductivity in their thickness directions only are provided at the portions corresponding to the protrusions 15 on the second wiring board 20. Then, an insulator of a resin 12 is laminated upon the wiring pattern 11 except the portions which are to be brought into contact with the protrusions 15, and the portions where the protrusions 15 are to be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer substrate in which a wiring pattern such as a copper foil is formed on the surface of an insulating substrate, and each insulating substrate is laminated in a plurality of layers, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in a multilayer board having a plurality of printed wirings formed thereon via an insulating layer, a method of providing a through-hole for conducting a wiring pattern on the front and back sides is performed by drilling a hole or through-hole in the board. Plating was required. Further, in order to connect to the component connection land, a through hole must be provided in a place different from the land portion.

Further, a method of forming a through hole by sandwiching a conductive material without using a through hole has been disclosed. As this method, there are, for example, the B ² IT method and the ALIVH method. In the B ² IT method, a sharp conductive portion is formed, and the front and back circuits are made conductive by breaking through an insulator.
The ALIVH method does not require via processing and plating with a drill. For example, a hole is formed with a carbon dioxide laser or the like, and the hole is filled with a conductive paste.

[0004]

In the former case of the prior art, a process for forming a through hole in an insulating substrate and plating an inner wall surface of the through hole of the through hole is complicated.
As a whole, man-hours were required. Also, in the case of the latter B ² IT method of the related art, it is not easy to form a sharp conductive portion, and many facilities are required.
It also depends on reliability. Therefore, the cost is high as a whole. In the case of the latter ALIVH, the laser is used to form the through-hole, so that the manufacturing apparatus becomes large and the manufacturing method is completely different, so that the conventional substrate technology cannot be used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional technology, and has as its object to provide a multilayer board which can increase the mounting density with a simple structure and is inexpensive, and a method of manufacturing the same. .

[0006]

SUMMARY OF THE INVENTION The present invention relates to a first wiring board having a first wiring pattern made of a conductor such as a copper foil, and a copper foil or the like to be electrically connected to the first wiring board. Providing a second wiring board having a second wiring pattern of
At least a part of a predetermined portion of a portion of the first wiring pattern to be electrically connected to the second wiring pattern is provided with a convex portion using a conductive paste containing copper or silver, and the second The multilayer substrate has an anisotropic conductor having conductivity only in the thickness direction attached to a portion corresponding to the convex portion on the wiring board. Then, the first wiring pattern and the second wiring pattern are electrically connected to each other by matching the corresponding portions. Further, the multilayer substrate is obtained by laminating an insulating resin on at least the wiring pattern, except for a portion where the convex portion contacts and a portion where the convex portion is to be formed. A plurality of sets of the first wiring board and the second wiring board are further laminated, and conduction is provided between the sets by the anisotropic conductor.

Further, the present invention comprises a first wiring board having a first wiring pattern, and a second wiring board having a second wiring pattern to be electrically connected to the first wiring board. The first wiring pattern to be electrically connected to the second wiring pattern is provided with a convex portion using a conductive paste, and a portion corresponding to the convex portion on the second wiring substrate is provided only in the thickness direction. Attach an anisotropic conductor having conductivity, pressurize in a state where the corresponding portions of both are combined to give conductivity only in the thickness direction, and form the first wiring pattern and the second wiring pattern This is a method for manufacturing a multilayer substrate to be electrically connected.

Further, the present invention comprises a first wiring board having a first wiring pattern, and a second wiring board having a second wiring pattern to be electrically connected to the first wiring board, The first wiring pattern to be electrically connected to the second wiring pattern is provided with a convex portion by a conductive paste, and after forming the convex portion, anisotropically so as to cover at least the top of the convex portion. The anisotropic conductor is applied, and the anisotropic conductor is pressed against the wiring pattern of the second wiring board to impart conductivity only in the thickness direction. This is a method for manufacturing a multi-layer board for connecting the wiring patterns. Further, an adhesive having an adhesive property is adhered on at least the wiring pattern except for a portion where the convex portion contacts and a portion where the convex portion is to be formed, and the first wiring substrate and the second wiring substrate are attached. This is a method for manufacturing a multilayer substrate that electrically conducts.

The present invention also includes a first wiring board having a first wiring pattern, and a second wiring board having a second wiring pattern to be electrically connected to the first wiring board, At least one of the first wiring pattern and the second wiring pattern is provided with a projection by a conductive paste at a portion where electrical conduction is to be performed between the first wiring pattern and the second wiring pattern. This is a method for manufacturing a multilayer board for connecting the first wiring pattern and the second wiring pattern by applying pressure by interposing an anisotropic conductor between the second wiring patterns. Further, an adhesive having an adhesive property is adhered on at least the wiring pattern except for a portion where the convex portion contacts and a portion where the convex portion is to be formed, and the first wiring substrate and the second wiring substrate are attached. Is to be joined.

The present invention further includes a first wiring board having a first wiring pattern, wherein a projection made of a conductive paste is provided on the first wiring pattern to be electrically connected to the second wiring pattern. Attaching an anisotropic conductor having conductivity only in the thickness direction to the first wiring pattern surface, further laminating a conductor thereon and pressing it, etching the conductor, and etching the second conductor. And a method of manufacturing a multilayer substrate in which the first wiring pattern and the second wiring pattern are electrically connected to each other. Then, the convex portion is formed at a portion of the second wiring pattern that is connected to the wiring pattern further laminated thereon, and an insulator is attached except for the convex portion forming portion, and the convex portion is formed. The above-described anisotropic conductor is attached and pressurized, and these operations are repeated to form a multilayer substrate.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a multi-layer substrate according to a first embodiment of the present invention. A wiring pattern 11 is formed on a first substrate 10 of this embodiment by copper foil. On the surface of the wiring pattern 11 and on the surface of the substrate other than the wiring pattern 11, an insulating resin 12 of an epoxy resin is laminated on almost the entire surface except for a portion where a connection portion is to be formed later. On the surface of the copper foil exposed portion 14 where a connection portion is to be formed later, a convex portion 15 of a conductive paste containing copper in a dot or convex shape narrower than the exposed portion 14 is provided.
Are formed. The protrusion 15 of the conductor paste is
Other materials such as lead and silver may be used as long as they have conductivity. This dot-shaped conductor paste is printed thickly so as to protrude beyond the height of the surrounding insulating resin 12 after drying.

A wiring pattern 11 made of copper foil is also formed on the second substrate 20, and a conductor portion 21 made of a conductor paste is provided thereon by screen printing.
An anisotropic conductor 22 having a somewhat larger area than the protrusion 15 is laminated between the conductor 21 and the protrusion 15 of the conductor paste of the first substrate 10. Anisotropic conductor 22
Is a resin mixed with, for example, Au-coated resin particles or Ni particles, and may be either a thermosetting resin or a thermoplastic resin. The particle diameter is about 3 to 5 μm, and the density in the resin is 10,000 to 40,000 particles /
mm ² . Examples of the thermosetting resin include an epoxy resin and a polyimide resin, and examples of the thermoplastic resin include:
There is a polyester resin. In addition, any material may be used as long as it generally has an insulating property and can obtain conductivity when pressed in the thickness direction. In addition, the conductor 21 may be formed as needed, and may not be provided.

In the method of manufacturing a multilayer substrate according to this embodiment, first, a first substrate 10 and a second substrate 20 are formed. First
The substrate 10 has a wiring pattern 11 formed by etching the surface copper foil. Then, an insulating resin 12 made of an epoxy resin is printed and hardened on almost the entire surface of the surface of the wiring pattern 11 and the surface of the substrate other than the wiring pattern 11 except for a portion where a connection portion is to be formed later. Further, on the surface of the copper foil exposed portion 14 where a connection portion is to be formed later, a convex portion 15 made of a conductive paste that is narrower than the exposed portion 14 and higher than the surrounding insulating resin 12 is formed.

The wiring pattern 11 of copper foil is also formed on the second substrate 20 by etching, and a conductor portion 21 is formed thereon by a conductor paste by screen printing. Then, the conductor portion 21 made of the conductor paste and the projection 15 made of the conductor paste of the first substrate 10 are formed.
Then, an anisotropic conductive paste is printed on the second wiring board 20 side so as to have a slightly larger area than the convex portion 15.

Next, the two substrates 10 and 20 are put together in a vacuum press so that the projection 15 of the first substrate 10 and the anisotropic conductor 22 of the second substrate 20 face each other. Set, pressurize, heat and cure. Thereby, the anisotropic conductor paste is given conductivity only in the thickness direction. Here, the conductive paste is cut and formed by printing, but if the number of points is small, the conductive paste may be individually applied using a dispenser. Also, as the pressing method,
The vacuum press method was used. This has the effect of preventing air from being caught between the layers and preventing swelling or the like due to air between the layers due to heating during subsequent soldering or the like.

Further, the same structure can be obtained by applying an anisotropic conductive paste on the first wiring board 10 after the conductive paste is applied to the first wiring board 10 and the projections 15 are hardened. Further, each of the substrates 10 and 20 may be a multi-layered or double-sided substrate, or may be multi-layered by repeating the above-described method.

According to the multi-layer substrate of this embodiment, it is possible to connect the circuits of the multi-layer substrate by repeating the printing process or the coating process. Further, since the anisotropic conductor 22 is used, the electric conductivity is reduced. In addition, it is only necessary to provide a projection of the conductor at the connection point without making a hole with a drill or the like.

Next, a multilayer substrate according to a second embodiment of the present invention and a method for manufacturing the same will be described with reference to FIG. Here, the same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted. The circuit board according to this embodiment includes a first board 1
0 of the conductive paste on the first wiring pattern 11
5 and further, after printing the paste of the anisotropic conductor 22 at a predetermined location, the entire surface on which the first wiring pattern 11 is formed is replaced with a copper foil or the like instead of the second wiring substrate. Is provided. Then, after applying pressure and heat and bonding, the conductor is etched to form the second wiring pattern 1.
Form one. Further, using this as the first substrate 10 again, the insulating resin 12 and the convex portion 15 slightly projecting from the insulating resin 12 are formed, and the anisotropic conductor 2 is formed thereon.
2 is repeated and laminated. Thereafter, wiring patterns of a required number of layers are formed, and the circuit board is multilayered.

According to the multi-layer substrate of this embodiment, a multi-layer substrate of an arbitrary layer can be efficiently formed, and the electrical connection is reliable.

Here, the patterning of each layer can be optically aligned. This eliminates mechanical errors such as thermal expansion as compared with mechanical alignment using a pin or the like, and improves positional accuracy.

Next, a multilayer substrate according to a third embodiment of the present invention and a method of manufacturing the same will be described with reference to FIG. Here, the same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted. In the circuit board of this embodiment, the anisotropic conductor 22 is not attached only to the necessary points, but is sandwiched in a sheet shape over the entire surface, so that the difference in the portion where the projection 15 made of the conductor paste is in contact is obtained. Only the isotropic conductor 22 is pressurized to provide conductivity in the thickness direction, and a portion without pressure can be used as an insulator.

In the case of this embodiment, it is preferable that an insulating material is interposed at portions other than the protrusions made of the conductive paste to be conducted. This is because the pressure may cause conductivity in the thickness direction other than the conductive portion in some cases. However, when there is no fear of this, the anisotropic conductor acts as an insulating layer, so that the anisotropic conductor may be provided over the entire surface, and portions other than the convex portions can function as the insulating layer.

[0023]

The multilayer board of the present invention can be manufactured by the same manufacturing process as that of the conventional wiring pattern, can be handled by general equipment and technology, and can be provided at a very low cost. Further, since the anisotropic material is used for the conductor, the reliability of electrical connection with the wiring pattern can be made extremely high. In addition, since the projections of the conductor are provided at the connection points, complicated and time-consuming steps such as drilling and through-hole plating can be omitted, which is efficient.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state of a multi-layer substrate according to a first embodiment of the present invention during manufacture.

FIG. 2 is a longitudinal sectional view of the multilayer substrate according to the first embodiment of the present invention.

FIG. 3 is a view showing a state at the time of manufacturing a multilayer substrate according to a second embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a multilayer substrate according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 First substrate 11 Wiring pattern 12 Insulator 15 Convex part 20 Second substrate 21 Conductor 22 Anisotropic conductor

Claims (9)

[Claims] 1. A first wiring board having a first wiring pattern made of a conductor, and a second wiring board having a second wiring pattern to be electrically connected to the first wiring board, At least a part of a predetermined portion of a portion of the first wiring pattern to be electrically connected to the second wiring pattern is provided with a convex portion with a conductive paste, and the convex portion is formed on the second wiring substrate. An anisotropic conductor having conductivity only in the thickness direction is attached to the portion corresponding to the portion, and the first and second wiring patterns are electrically connected to each other by combining the corresponding portions. Multilayer substrate. 2. The multi-layer substrate according to claim 1, wherein an insulator is attached to at least the wiring pattern except for a portion where the projection contacts and a portion where the projection forms. 3. The multilayer according to claim 1, wherein a plurality of sets of the first wiring board and the second wiring board are further laminated, and the respective sets are electrically connected by the anisotropic conductor. substrate. 4. A semiconductor device comprising: a first wiring board having a first wiring pattern; and a second wiring board having a second wiring pattern to be electrically connected to the first wiring board. The first wiring pattern to be electrically connected to the first wiring pattern is provided with a convex portion with a conductive paste, and the portion corresponding to the convex portion on the second wiring substrate is electrically conductive only in the thickness direction. A method of manufacturing a multilayer substrate, wherein an anisotropic conductor having the following characteristics is adhered, and pressure is applied in a state where the corresponding portions of the two are combined to electrically connect the first wiring pattern and the second wiring pattern. 5. A semiconductor device comprising: a first wiring board having a first wiring pattern; and a second wiring board having a second wiring pattern to be electrically connected to the first wiring board. The first wiring pattern to be electrically connected to the first wiring pattern is provided with a convex portion with a conductive paste, and after forming the convex portion, the anisotropic conductor is further covered so as to cover at least the top of the convex portion. And bonding the anisotropic conductor to the wiring pattern of the second wiring substrate by applying pressure and pressure. 6. A semiconductor device comprising: a first wiring board having a first wiring pattern; and a second wiring board having a second wiring pattern to be electrically connected to the first wiring board. At least one of the wiring pattern and the second wiring pattern is provided with a convex portion by a conductive paste at a portion where electrical conduction is to be performed between the two, and thereafter, the first wiring pattern and the second wiring pattern are provided. A method for manufacturing a multilayer board, wherein an anisotropic conductor is interposed between wiring patterns and pressurized to connect the first wiring pattern and the second wiring pattern. 7. An adhesive having an adhesive property is adhered on at least the wiring pattern except for a portion where the protrusion contacts and a portion where the protrusion is to be formed. 7. The method for manufacturing a multilayer board according to claim 4, wherein the wiring board is bonded to the wiring board. 8. A first wiring board having a first wiring pattern, wherein the first wiring pattern to be electrically connected to the second wiring pattern is provided with a projection made of a conductive paste, An anisotropic conductor having conductivity only in the thickness direction is attached to one wiring pattern surface, a conductor is further provided thereon and pressurized, and the conductor is etched to form the second wiring pattern. A method of manufacturing a multilayer substrate, which is formed and electrically connects the first wiring pattern and the second wiring pattern. 9. The convex portion is formed at a portion of the second wiring pattern that is connected to a wiring pattern laminated thereon, and an insulator is attached except for the convex portion forming portion. 9. The method for manufacturing a multilayer substrate according to claim 8, wherein the anisotropic conductor is attached to the projections, heated under pressure, and these operations are repeated to form a multilayer substrate.