JPH10335827A - Multilayered circuit board and hybrid integrated circuit using the board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered circuit board which has a high interlayer connection reliability and a good productivity. SOLUTION: This is a multilayer circuit board, wherein at least one of conductor circuit layers 3 which is not the outermost layer is partially exposed, and at least one of the conductor circuit layers having exposed sections is electrically connected to the conductor circuit layer in the outermost layer via a conductive adhesive 7 and a conductive component 8. In such a multilayered circuit board, the shape of the exposed section is preferably a square or a rectangle, and the area is 0.25 mm<2> or larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer circuit board excellent in productivity and excellent in reliability of interlayer connection and a hybrid integrated circuit using the same.

[0002]

2. Description of the Related Art In recent years, for the purpose of achieving high-density mounting of semiconductor elements, a circuit board having a multilayer structure in which a plurality of wiring circuits are stacked via an insulating layer has attracted attention. Means to achieve multilayer wiring circuits include a method of laminating double-sided circuit boards several layers via prepreg, but bonding copper foil to the outermost layers on both sides via prepreg, or building up on the base material A method of sequentially forming an insulating layer and a conductor circuit by a method is known, but in any case, the method of electrically connecting the conductor circuits of each layer is a method using copper plating or a noble metal paste. It has become mainstream.

[0003] However, in order to perform copper plating, it is necessary to go through obscene steps such as drilling, pre-treatment, and desmear treatment, which is not satisfactory in terms of productivity.

The method using a noble metal paste is good in terms of productivity, but is insufficient in terms of interlayer connection reliability, and is not suitable for applications requiring long-term reliability.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and at least one of the conductor circuits which is not the outermost layer of a multilayer circuit board is partially exposed. By electrically connecting at least one of the conductive circuits having the exposed portion to the outermost conductive circuit via a conductive adhesive and a conductive component, a multilayer circuit board having excellent interlayer connection reliability is obtained. It is based on the finding that it can be formed with high productivity.

That is, an object of the present invention is to provide a multilayer circuit board having excellent interlayer connection reliability with high productivity.

[0007]

According to the present invention, a plurality of conductive circuit layers are laminated on a base material via an insulating layer, and at least one of the conductive circuit layers which is not the outermost layer is partially formed. A multilayer circuit board exposed at least one of the conductive circuit layers having the exposed portions, wherein at least one of the conductive circuit layers having the exposed portions is electrically connected to an outermost conductive circuit layer via a conductive adhesive and a conductive component. A multilayer circuit board characterized by being connected to a multi-layer circuit board.

[0008] The present invention also provides that the exposed portion has a rectangular shape and / or a square shape when viewed from a direction perpendicular to the substrate, and preferably, an area of the exposed portion when viewed from a direction perpendicular to the substrate. However, in any of the above-mentioned multilayer circuit boards, each of them is 0.25 mm ² or more. Further, the present invention is the multilayer circuit board described above, wherein the conductive component is a jumper wire or a chip resistor.

[0009] In addition, the present invention is a hybrid integrated circuit in which electronic components are mounted on the multilayer circuit board.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of an example of the multilayer circuit board of the present invention. The conductor circuit layer 3 is placed on the base material 1, the insulating layer 4 is placed on the conductor circuit layer 3, the conductor circuit layer 5 is placed on the insulating layer 4, and the conductor circuit layer 3 is placed on the substrate 1. At a portion that is partially exposed, the conductive circuit layer 5 is electrically connected to the outermost conductive circuit layer 5 via the conductive adhesive 7 and the conductive component 8. That is, in the present invention, a plurality of conductor circuit layers are laminated on a base material via an insulation layer, and the conductor circuit that is not the outermost layer is partially exposed and the insulation layer on the conductor circuit, the conductor circuit is missing and exposed. It is only necessary that the conductor circuit having the exposed portion be electrically connected to the outermost conductor circuit via the conductive adhesive and the conductive component.

An insulating layer 2 may be interposed on the substrate 1 if necessary. A solder resist 6 is formed on the conductor circuit layer 5 as needed. Although not shown, an electronic element may be mounted on the outermost conductive circuit layer 5 as necessary, or may be connected to another component by wire bonding or the like. Further, between the conductor circuit layer 3 and the insulation layer 4, a combination of other conductor circuit layers and the insulation layer may be of a multi-layer structure. In this case, the plurality of insulating layers need not necessarily have the same composition. Furthermore, the conductor circuit layers 3 and 5 need only be placed on at least a part of at least one main surface of the substrate 1, and at least one other circuit board is laminated on the outermost conductor circuit layer. It does not matter. In addition, a plurality of conductor circuit layers may be exposed, or a plurality of partially exposed conductor circuit layers may of course be provided. Furthermore, it is not necessary that all of the plurality of exposed locations be electrically connected to the outermost conductive circuit layer via a conductive component and a conductive adhesive.

In the multilayer circuit board of the present invention, the exposed portion of the circuit conductor layer is rectangular and / or square when viewed from the component mounting surface side, and preferably, the exposed portion has an area of 0.25 mm ² or more. It is. Regarding the shape of the exposed portion of the circuit conductor layer, according to the study of the present inventor, when it is rectangular or square, it has parallel edges, so the conductive component is electrically connected to the conductor circuit using a conductive adhesive or the like. When electrically connected, the lead terminals of the conductive parts are easy to fix, and have two edges parallel to the conductor circuit that is often bent at a right angle, so that the fixing is easier and more preferable. Further, when the area is 0.25 mm ² or more, it is extremely easy to fix the conductive component, which is preferable.

The exposed portion is formed by removing the insulating layer 4 on the circuit conductor layer 3 and the upper circuit conductor layer 5 further. The insulating layer can be removed by using a general method of processing a via hole or a through hole. Examples of these methods include a method using various laser beams such as an excimer laser, a CO ₂ laser, and a YAG laser. A method of dissolving the small holes for electrical connection after patterning by exposing the insulating layer with a photosensitive resin, or a method of dissolving the insulating layer chemically by chemical drilling or mechanically forming the insulating layer by sandblasting. There is a method of removing. However, according to the study of the present inventors, a predetermined position of the outermost conductive circuit layer 5 is removed by etching, a hole is opened to the insulating layer 4 immediately below, and the bottom of the hole is irradiated with a laser beam to form the insulating layer 4. The method of forming a small hole for electrical connection by removing is preferred because the dimensional accuracy is high, the peripheral portion is not damaged, and the productivity is good.

In the present invention, a jumper wire or a chip resistor can be used as the conductive component 8 so as to obtain desired circuit characteristics. As the material of the jumper wire, copper, iron, aluminum, nickel, lead, tin,
In addition to metals such as silver and titanium, conductive nonmetals, or compounds or mixtures containing two or more kinds of materials can be used. Further, as the conductive adhesive 7, it is only necessary to have both conductivity and adhesiveness, such as solder or various adhesives containing conductive powder, or welding, and eutectic solder is generally used. Conventionally, copper plating or conductive paste had to be performed to electrically connect the conductive circuit layers of the multilayer circuit board. However, when mounting electronic components on the multilayer circuit board, the conductive By electrically connecting the outermost conductive circuit layer and the inner conductive circuit layer with the conductive adhesive 8 and the conductive adhesive 7, the above step becomes unnecessary.

As the resin constituting the insulating layers 2 and 4, various engineering plastics other than epoxy resin, phenol resin and polyimide resin can be used alone or in combination of two or more. Among them, epoxy resin is used. It is preferable because the bonding strength between metals is excellent. Particularly, among the epoxy resins, bisphenol A type epoxy resin and bisphenol F type epoxy resin, which have high fluidity and are excellent in mixing with various ceramic powders, are more preferable resins. These resins may be filled with glass fiber or ceramic powder.

The material of the conductor circuits 3 and 5 may be any one of copper, aluminum, nickel, iron, tin, silver and titanium, or an alloy containing two or more of these metals, and a clad foil using each metal. Can be used.
In addition, the method of manufacturing the foil at this time may be one produced by an electrolytic method or a rolling method, and the metal plating such as Ni plating, Ni-Au plating, and solder plating may be applied on the foil, From the viewpoint of adhesion to the insulating layer 2, it is more preferable that the surface of the conductive circuit layer 3 has been roughened in advance by etching, blackening, plating, or the like.

In the present invention, the material and thickness of the substrate 1 are not particularly limited, and a general resin plate or metal plate can be widely used.

Hereinafter, the present invention will be described in more detail with reference to Examples.

[0019]

【Example】

Example 1 A predetermined circuit was formed on both sides of a double-sided glass epoxy substrate (R1766, manufactured by Matsushita Electric Works, Ltd .; 250 mm × 500 mm × 1.6 mm, each having a copper foil thickness of 35 μm), and then prepreg (Matsushita Electric Works) R16
61), a copper foil having a thickness of 35 μm was press-laminated on both sides to form a predetermined circuit on the outer copper foil, thereby producing a four-layer board. A small hole of φ0.3 mm reaching the insulating layer immediately below is drilled at a desired position of the outermost conductive circuit layer of the circuit board, and a CO ₂ laser is applied to the bottom of the small hole, whereby the outer conductive circuit is formed. A small hole extending from the layer to the inner conductor circuit layer was provided. After the inside of the small holes was desmeared with a potassium permanganate solution, the inner conductor circuit and the outer conductor circuit layer were electrically connected to each other by an iron jumper wire and eutectic solder. The interlayer connection reliability and productivity of this multilayer circuit board were examined by the following methods. The results are shown in Table 1.

<Evaluation method of interlayer connection reliability> JIS C
In accordance with the method of the thermal shock (high temperature immersion) test specified in No. 5012, the evaluation was made based on the rate of change of the conductor resistance to the initial value after 100 cycles of thermal shock was applied to the substrate.

<Productivity Evaluation Method> Business card size (90 m
The evaluation was based on the time required to manufacture 10,000 substrates (m × 50 mm).

[0022]

[Table 1]

[Example 2] 250 mm x 500 mm x
A predetermined circuit is formed on both surfaces of a double-sided glass epoxy substrate (R1766, manufactured by Matsushita Electric Works, Ltd .; R1766, manufactured by Matsushita Electric Works, Ltd.) having a thickness of 1.6 mm and a copper foil thickness of 35 μm, and then via a prepreg (R1661, manufactured by Matsushita Electric Works, Ltd.). Then, a copper foil having a thickness of 35 μm was press-laminated on both sides to form a predetermined circuit on the outer copper foil, thereby producing a four-layer board. Drill to a desired position of the outer conductor circuit layer of the circuit board and reach the insulating layer immediately below φ
A small hole of 0.3 mm was made, and a CO ₂ laser was applied to the bottom of the small hole to form a small hole extending from the outer conductive circuit layer to the inner conductive circuit layer. After the inside of the small holes was desmeared with a potassium permanganate solution, the inner conductor circuit layer and the outer conductor circuit layer were electrically connected by a chip resistor and eutectic solder. The interlayer connection reliability and the productivity of this multilayer circuit board were examined in the same manner as in Example 1.
The results are shown in Table 1.

Example 3 250 mm × 500 mm ×
A predetermined circuit is formed on both surfaces of a double-sided glass epoxy substrate (R1766, manufactured by Matsushita Electric Works, Ltd .; R1766, manufactured by Matsushita Electric Works, Ltd.) having a thickness of 1.6 mm and a copper foil thickness of 35 μm, and then via a prepreg (R1661, manufactured by Matsushita Electric Works, Ltd.). Then, a copper foil having a thickness of 35 μm was press-laminated on both sides to form a predetermined circuit on the outer copper foil, thereby producing a four-layer board. Drill to a desired position of the outer conductor circuit layer of the circuit board and reach the insulating layer immediately below φ
A small hole of 0.3 mm was made, and a CO ₂ laser was applied to the bottom of the small hole to form a small hole extending from the outer conductive circuit layer to the inner conductive circuit layer. After the interior of the small hole was desmeared with a potassium permanganate solution, the inner conductive circuit layer and the outer conductive circuit layer were electrically connected by welding with an iron jumper wire. The interlayer connection reliability and the productivity of this multilayer circuit board were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 4 250 mm × 500 mm ×
A predetermined circuit is formed on both surfaces of a double-sided glass epoxy substrate (R1766, manufactured by Matsushita Electric Works, Ltd .; R1766, manufactured by Matsushita Electric Works, Ltd.) having a thickness of 1.6 mm and a copper foil thickness of 35 μm, and then via a prepreg (R1661, manufactured by Matsushita Electric Works, Ltd.). Then, a copper foil having a thickness of 35 μm was press-laminated on both sides to form a predetermined circuit on the outer copper foil, thereby producing a four-layer board. A hole of 0.25 mm square reaching the insulating layer immediately below is drilled at a desired position of the outermost conductive circuit layer of the circuit board, and a CO ₂ laser is applied to the bottom of the hole to form the outermost layer. Small holes were provided from the conductor circuit layer to the inner conductor circuit layer. After the inside of the small hole was desmeared with a potassium permanganate solution, the inner conductor circuit layer and the outer conductor circuit layer were electrically connected to each other by an iron jumper wire and eutectic solder. The interlayer connection reliability and the productivity of this multilayer circuit board were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 5 250 mm × 500 mm ×
A predetermined circuit is formed on both surfaces of a double-sided glass epoxy substrate (R1766, manufactured by Matsushita Electric Works, Ltd .; R1766, manufactured by Matsushita Electric Works, Ltd.) having a thickness of 1.6 mm and a copper foil thickness of 35 μm, and then via a prepreg (R1661, manufactured by Matsushita Electric Works, Ltd.). Then, a copper foil having a thickness of 35 μm was press-laminated on both sides to form a predetermined circuit on the outer copper foil, thereby producing a four-layer board. A 0.5 mm square hole reaching the insulating layer immediately below is drilled at a desired position of the outer conductive circuit layer of the circuit board, and a CO ₂ laser is applied to the bottom of the small hole. A small hole extending from the layer to the inner conductor circuit layer was provided. After the inside of the small hole was desmeared with a potassium permanganate solution, the inner conductor circuit layer and the outer conductor circuit layer were electrically connected to each other by an iron jumper wire and eutectic solder. The interlayer connection reliability and the productivity of this multilayer circuit board were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 6 250 mm × 500 mm ×
A predetermined circuit is formed on both surfaces of a double-sided glass epoxy substrate (R1766, manufactured by Matsushita Electric Works, Ltd .; R1766, manufactured by Matsushita Electric Works, Ltd.) having a thickness of 1.6 mm and a copper foil thickness of 35 μm, and then via a prepreg (R1661, manufactured by Matsushita Electric Works, Ltd.). Then, a copper foil having a thickness of 35 μm was press-laminated on both sides to form a predetermined circuit on the outer copper foil, thereby producing a four-layer board. A hole of 0.5 mm × 1.0 mm reaching the insulating layer immediately below is drilled at a desired position of the conductor circuit layer on the outer layer of the circuit board, and a CO ₂ laser is applied to the bottom of the hole. A small hole extending from the conductive circuit layer of No. 1 to the inner conductive circuit layer was provided. After desmearing the inside of this small hole with potassium permanganate solution,
The inner conductive circuit layer and the outer conductive circuit layer were electrically connected by an iron jumper wire and eutectic solder. Example 1 The interlayer connection reliability and the productivity of this multilayer circuit board were evaluated in Example 1.
I examined it in the same way. The results are shown in Table 1.

[Embodiment 7] Predetermined electronic components were mounted on the multilayer circuit board of Embodiment 6 in which the inner conductor circuit layer was a shield pattern, and a hybrid integrated circuit as a DC / DC converter was prepared. When the hybrid integrated circuit was operated, generation of noise was extremely small, and no other electrical abnormality was observed.

Comparative Example 1 250 mm × 500 mm ×
A predetermined circuit is formed on both surfaces of a double-sided glass epoxy substrate (R1766, manufactured by Matsushita Electric Works, Ltd .; R1766, manufactured by Matsushita Electric Works, Ltd.) having a thickness of 1.6 mm and a copper foil thickness of 35 μm, and then via a prepreg (R1661, manufactured by Matsushita Electric Works, Ltd.). Then, a copper foil having a thickness of 35 μm was press-laminated on both sides to form a predetermined circuit on the outer copper foil, thereby producing a four-layer board. Drill to a desired position of the outer conductor circuit layer of the circuit board and reach the insulating layer immediately below φ
A small hole of 0.3 mm was made, and a CO ₂ laser was applied to the bottom of the small hole to form a small hole extending from the outer conductive circuit layer to the inner conductive circuit layer. After the inside of the small hole was desmeared with a potassium permanganate solution, the inner conductive circuit layer and the outer conductive circuit layer were electrically connected by a silver paste (LS-506J manufactured by Asahi Kaken). The interlayer connection reliability and the productivity of this multilayer circuit board were examined in the same manner as in Example 1. These results are shown in Table 1, but were insufficient in terms of interlayer connection reliability.

Comparative Example 2 250 mm × 500 mm ×
A predetermined circuit is formed on both surfaces of a double-sided glass epoxy substrate (R1766, manufactured by Matsushita Electric Works, Ltd .; R1766, manufactured by Matsushita Electric Works, Ltd.) having a thickness of 1.6 mm and a copper foil thickness of 35 μm, and then via a prepreg (R1661, manufactured by Matsushita Electric Works, Ltd.). Then, a copper foil having a thickness of 35 μm was press-laminated on both sides to form a predetermined circuit on the outer copper foil, thereby producing a four-layer board. Drill to a desired position of the outer conductor circuit layer of the circuit board and reach the insulating layer immediately below φ
A small hole of 0.3 mm was made, and a CO ₂ laser was applied to the bottom of the small hole to form a small hole extending from the outer conductive circuit layer to the inner conductive circuit layer. After the interior of the small holes was desmeared with a potassium permanganate solution, the inner conductive circuit layer and the outer conductive circuit layer were plated with copper with a thickness of 20 μm and electrically connected. The interlayer connection reliability and the productivity of this multilayer circuit board were examined in the same manner as in Example 1. The results are shown in Table 1, but were insufficient in productivity.

[0031]

The multilayer circuit board of the present invention has excellent interlayer connection reliability, so that it can be used for various applications with ease. According to the manufacturing method of the present invention, the multilayer circuit board is produced. Since it can be provided with good quality, it is very useful in industry.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a multilayer circuit board of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base material 2 insulating layer 3 conductive circuit layer 4 insulating layer 5 conductive circuit layer 6 solder resist 7 conductive adhesive 8 conductive component

Claims (6)

[Claims] 1. A multilayer circuit board comprising a plurality of conductive circuit layers laminated on a base material via an insulating layer, and at least one of the conductive circuit layers which is not the outermost layer is partially exposed. Wherein at least one of the conductor circuit layers having the exposed portions is electrically connected to an outermost conductor circuit layer via a conductive adhesive and a conductive component at the exposed portions. Characteristic multilayer circuit board. 2. The multilayer circuit board according to claim 1, wherein each of the exposed portions is rectangular and / or square when viewed from a direction perpendicular to the substrate. 3. The multilayer circuit board according to claim 2, wherein the area of each of the exposed portions when viewed from a direction perpendicular to the substrate is 0.25 mm ² or more. 4. The multilayer circuit board according to claim 1, wherein the conductive component is a jumper wire. 5. The multilayer circuit board according to claim 1, wherein the conductive component is a chip resistor. 6. A hybrid integrated circuit in which electronic components are mounted on the multilayer circuit board according to claim 1, 2, 3, 4, or 5.