JPH09283931A - Multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer wiring board which is easy to form a multilayer board and has a high reliability realized by improving the production yield. SOLUTION: Wiring boards 14a, 14b having interconnection patterns formed on the surface of at least one of core board 10a, 10b are laminated through board bonding layer 16 in one body which bond the wiring board 14a, 14b and electrically connect the wiring patterns of these boards 14a, 14b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board used for manufacturing semiconductor devices and the like.

[0002]

2. Description of the Related Art A multilayer wiring board is one in which insulating layers and conductor layers are alternately laminated to form a multilayer conductor layer, and is used as a substrate for high-density wiring in semiconductor devices and the like.
As a method of forming a multilayer wiring board, a thin film method in which a conductor layer is formed by a sputtering method or the like, and a so-called photolithography method is used to form a multilayer, or a photosensitive resin is used for an insulating layer, and so-called multi-layer formation is performed in combination with plating is performed. The build-up method is known.

In the thin film method or the build-up method, it is possible to form a multi-layered conductor layer with an arbitrary number of layers by repeating a predetermined operation. However, a multi-layer forming method such as a thin film method or a build-up method requires a fairly high level of technology, and the current technology does not always provide sufficient reliability when the conductor layer is formed in multiple layers.

As described above, since the multilayer wiring board is technically difficult, as a method of reducing the defective rate of products and increasing the manufacturing yield, a wiring pattern with a plurality of layers on a substrate such as a metal plate or a ceramic plate. Prepare the formed
There is a method in which layered portions are aligned and bonded integrally, and then the substrate is peeled off to form a wiring pattern in multiple layers (Japanese Patent Laid-Open No. 5-144973). Since this manufacturing method combines a plurality of wiring patterns to form a multilayer structure, the manufacturing method is more reliable than a method of sequentially forming a multilayer structure from the base. This is because, in the case of the method of stacking from the base, the entire wiring board becomes a defective product even if only one intermediate layer has a defect.

[0005]

In the conventional multi-layer wiring board prepared by the build-up method or the like as described above, the problem is that defective products are likely to occur, and it is required to improve the manufacturing yield. ing. In addition, the method of forming a multilayer by laminating from the base takes a manufacturing time in proportion to the number of layers,
Because of the high manufacturing cost, there is a need for a method of forming multiple layers more easily. For example, even when the wiring patterns are formed on the substrate in multiple layers as in the above example, the substrates must be peeled off and removed from the laminated body after the wiring patterns are joined, and finally the multilayer formation is performed. There is a problem that it takes a lot of man-hours to do so, the process is complicated and the manufacturing cost is increased.

The present invention has been made to solve these problems, and an object of the present invention is to facilitate the formation of multiple conductor layers to improve the manufacturing yield.
Further, it is an object of the present invention to provide a multilayer wiring board which can easily obtain a highly reliable multilayer wiring board and can reduce the manufacturing cost.

[0007]

The present invention has the following constitution in order to achieve the above object. That is, a plurality of wiring boards having wiring patterns formed in a plurality of layers are aligned and laminated on at least one outer surface of a core board having a wiring pattern formed thereon. It is characterized in that the wiring patterns formed on the outer surface of the wiring board are electrically connected to each other through a bonding layer to be integrally bonded. Further, the board bonding layer is constituted by a bonding sheet body in which a low melting point metal for electrically connecting the wiring patterns is supported by a resin for bonding the wiring boards. Further, the wiring board is characterized in that wiring patterns are formed on both surfaces of the core board. Further, the core substrate is a printed circuit board in which a plurality of wiring patterns electrically connected between layers are formed. The core substrate is a ceramic substrate having a plurality of wiring patterns electrically connected between layers. Further, the wiring board is characterized in that a plurality of wiring patterns are formed on the surface of the core board by a build-up method. Further, the wiring board is characterized in that a plurality of wiring patterns are formed on the surface of the core board by a thin film method.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. FIG. 1 is a sectional view showing an embodiment of a multilayer wiring board according to the present invention. In the multilayer wiring board of the present embodiment, printed boards are core boards 10a and 10b, and wiring boards 14a and 14b having several layers of wiring patterns 12 formed on both surfaces of the core boards 10a and 10b are connected to a board bonding layer 16.
And the wiring patterns 12 between the substrates are electrically connected together.

As described above, the multilayer wiring board of this embodiment is formed by joining the wiring boards 14a and 14b having the wiring patterns 12 formed in a plurality of layers on both surfaces of the core boards 10a and 10b. 2 to 6 show a method of manufacturing the wiring board 14 used for manufacturing the multilayer wiring board. FIG. 2 is a cross-sectional view of the core substrate 10 formed by the printed circuit board. The core substrate 10 is a multi-layer substrate which is composed of four layers of wiring patterns including an inner layer wiring pattern 18a and an outer surface wiring pattern 18b.

The wiring patterns 18a and 18b between the layers are electrically connected to each other by performing through-hole plating on the through-hole 20 provided through the substrate. A resin is sealed in the through hole 20. As the base material forming the core substrate 10, for example, BT (bismaleimide triazine) resin, epoxy resin or the like can be used.

A method of forming the wiring patterns 12 in multiple layers on the outer surface of the core substrate 10 is a thin film method or a build-up method. The method of forming by the build-up method is shown below. First, a photosensitive resin to be the electrically insulating layer 22 is applied to the outer surface of the multilayer substrate 10 in which the above wiring patterns are formed in multiple layers. Next, the photosensitive resin is exposed and developed to form via holes 24 that communicate with the wiring pattern 18b provided on the substrate from the surface of the electrically insulating layer 22 (FIG. 3). As a result, the wiring pattern 18b is exposed at the via hole 24 portion.

Next, electroless plating is performed and then electrolytic plating is performed to provide a conducting portion 26 on the inner surface of the via hole 24 for electrically connecting the wiring patterns between the layers. A conductor layer made of plated metal is formed on the entire surface of the electrically insulating layer 22 previously formed by the electroless plating and electrolytic plating. FIG. 4 shows a state where a predetermined wiring pattern 12 is formed by etching this conductor layer. The method of etching the conductor layer to form the wiring pattern 12 is to apply a photosensitive resist to the surface of the conductor layer, expose and develop the photosensitive resist to form a resist pattern, and perform etching using the resist pattern as a mask. It depends on the method.

This wiring pattern 1 is provided through an electrically insulating layer.
In order to electrically connect to 2 and form a next wiring pattern as a layer, the above operation may be repeated. That is, the photosensitive resin is applied again to the surfaces of the wiring pattern 12 and the electrically insulating layer 22 formed previously to form the electrically insulating layer 22, and the photosensitive resin is exposed and developed to provide the via hole 24. (Fig. 5).

Next, electroless plating and electrolytic plating are performed to provide the via holes 24 with conductive portions 26 for electrically connecting the wiring patterns 12 between the layers, and further, the electrically insulating layer 22.
The conductor layer formed on the surface of is electrically etched to form the wiring pattern 12 on the surface of the electrically insulating layer 22. FIG. 6 shows the wiring board 14 thus obtained. The wiring board 14 is obtained by performing the above operations on both surfaces of the core board 10.
Two wiring patterns 12 are formed via the electrically insulating layer 22. Looking at the wiring board 14 as a whole, the core board 1
0 has four layers of wiring patterns 18a and 18b, and since the wiring pattern 12 on the outer surface of the core substrate 10 has four layers, it is composed of a total of eight layers of wiring patterns.

The multilayer wiring board of the present embodiment is one in which the wiring board 14 obtained as described above is bonded by a board bonding layer 16 as shown in FIG. The function of the board bonding layer 16 is to bond the wiring boards 14a and 14b together and at the same time electrically connect the wiring patterns 12 formed on the surfaces of the wiring boards 14a and 14b to electrically connect the multilayer wiring board as a whole. To take.

To join the wiring boards 14a and 14b,
For example, two wiring boards 14 that are to be joined together
On one of the laminated surfaces of a and 14b, a solder paste such as lead-tin eutectic solder containing copper powder as a connecting portion and an epoxy varnish as a connecting portion are printed to form a wiring board 14a, 14b.
b can be aligned with each other and pressed and heated to join them together. In FIG. 1, 30 is a wiring board 14a, 1
4b is a connecting portion for electrically connecting the wiring patterns 12 on the laminated surface. The connection portion 30 can be accurately arranged by applying a solder paste in accordance with the arrangement position of the wiring pattern 12 by screen printing.

FIG. 1 thus shows two wiring boards 14a,
14b is a multilayer wiring board obtained by integrally bonding 14b with the board bonding layer 16. The obtained multilayer wiring board has 16 wiring pattern layers as a whole. In this multilayer wiring board, the core board 10 having several wiring patterns 12 formed on the outer surface of the board is used as it is for the constituent parts of the multilayer wiring board, and the wiring patterns 18a and 18b of the core board 10 and the wiring pattern 12 are electrically connected. This is characterized in that a wiring pattern is formed in multiple layers.

In the above embodiment, as the wiring board 14 to be integrally joined, the one in which two layers of the wiring patterns 12 are formed on the outer surface of the core board 10 is used. As described above, when the multilayer wiring board of the present embodiment is manufactured, it is preferable that the wiring pattern 12 formed on the core substrate 10 has about 2 to 3 layers. This is because when the wiring pattern 12 is formed on the outer surface of the core substrate 10 by a build-up method or the like, it is possible to form the wiring pattern with sufficient accuracy and certainty if it is formed in about 2 to 3 layers. This is because the reliability at the time of manufacturing can be improved. When the wiring boards 14 are joined to form a multilayer wiring board, the quality of the wiring board 14 is inspected in advance, and only good products are joined. As a result, the defective rate of the multilayer wiring board can be reduced, and the manufacturing yield can be improved. In this way, if the step of manufacturing the wiring board 14 and the step of joining the wiring boards 14 are separate steps, the wiring board 14 can be easily manufactured, and since it is possible to work in parallel, a multilayer wiring board can be efficiently manufactured. It also has the advantage that it can be produced.

In the above embodiment, a plastic substrate is used as the base material of the wiring board 14, and the wiring pattern 12 formed on the outer surface of the board is formed by the build-up method.
The material of the wiring board 14 is not particularly limited,
It is also possible to use a ceramic substrate. When a ceramic substrate is used, a wiring substrate having a plurality of wiring patterns formed on the outer surface of the ceramic substrate by a thin film method or the like is used. It is obtained by joining together.

In the multilayer wiring board of the above-described embodiment, the wiring board 14 to be integrally joined is provided with the wiring patterns 12 on each of several layers, but the wiring pattern 12 is provided only on the laminated surface of the wiring board 14. There is also a possibility. For example, the wiring pattern 18b provided on the outer surface of the core substrate 10
This is a case where an external connection terminal is attached to a mounting surface on a mounting board. In this case, since the wiring pattern 18b of the core substrate 10 has a higher peel strength than the wiring pattern 12 formed by the build-up method or the like, the bonding strength of the external connection terminal can be increased.

Further, the wiring board 14 is not limited to the case of joining two pieces as in the above example, and it is of course possible to join three or more pieces. The core board 10 used for the wiring board 14 is functionally useful when the wiring pattern 18a is provided in the inner layer, but it is of course possible to use the core board 10 in which the wiring pattern 18a of the inner layer is not provided. However, the core substrate 10 needs to electrically connect the wiring patterns 18b on both outer surfaces with vias or the like.

When the wiring board 14 is joined to form a multilayer wiring board, it is possible to integrally join wiring boards made of different materials such as a plastic substrate and a ceramic substrate. Further, in the above embodiment, the solder paste and the epoxy varnish were used as the method for joining the wiring board 14, but as the method for joining the wiring board 14, other than this, a film containing an anisotropic conductive adhesive is used. A combination of a conductive resin and an adhesive resin paste or prepreg, a combination of a solder paste and an adhesive resin paste or prepreg, and the like can be used. Further, when a wiring board made of a ceramic substrate is bonded, it is possible to use a combination of a low melting point alloy and a low melting point glass.

As described above, various kinds of substrate bonding layers 16 for bonding the wiring boards 14 are conceivable, but a low melting point metal 42 as shown in FIG. The joining sheet 40 supported by the resin 44 is useful. The bonding sheet 40 is for electrically connecting the wiring pattern 12 on the bonding surface of the wiring board 14 with the low melting point metal 42 and integrally bonding the wiring board 14 with the resin 44.

In order to obtain a highly reliable multilayer wiring board, the wiring patterns 12 should be electrically and reliably connected when the wiring boards 14 are joined, and the wiring board 14 should be stably and surely bonded. is important. The joining sheet 40 enables such highly reliable joining of wiring boards.
That is, in the joining sheet 40, a large number of wires made of a low melting point metal are embedded in a block-like resin material 46 as shown in FIG. 8 at a predetermined interval from one end face to the other end face in parallel with the axis. It is obtained by slicing the block body 48 with a predetermined thickness on a plane perpendicular to the axis of the block body 48.

FIG. 9 shows a joining sheet body 50 obtained by slicing the block body 48. Since the joining sheet body 50 is obtained by slicing the block body 48, as shown in FIG. 7, the low-melting-point metal 42 is formed in the same thickness as the sheet and is supported by the resin 44, and both end surfaces of the low-melting-point metal 42 are supported. Is exposed on both sides of the sheet. A plurality of the joining sheets 40 can be obtained from one of the joining sheet bodies 50 of the embodiment.

The resin material 46 may be a thermosetting resin such as an epoxy resin, a polyimide resin, an unsaturated polyester resin, a polyphenylene ether resin, or the like, and a thermoplastic resin such as a polyamide resin, a saturated polyester resin, or a polyurethane resin. Resin etc. can be used. When a thermosetting resin is used, it is used in a semi-cured state (B stage), and when a thermoplastic resin is used, it is completely cured before use. As the low melting point metal 42, tin-lead based solder,
Alternatively, as the lead-free solder, tin-silver solder, tin-antimony solder, tin-bismuth-silver solder, or the like can be used.

The block 48 can be appropriately prepared by combining the above resin material with a low melting point metal or the like. In the following, an epoxy resin is used as the resin material and a lead-tin eutectic alloy is used as the low melting point metal. A method of manufacturing the block body 48 in the case will be described. First, the epoxy resin used as the resin material 46 is adjusted to about 250 centipoise and filled in a cylindrical container whose inner surface is covered with silicone rubber in the A stage state.

In the cylindrical container, a lead-tin eutectic alloy is used.
A large number of wires having a diameter of 5 mm are erected from the bottom surface and supported by being stretched between the wires and the opening of the container. A support frame for supporting the wires in parallel with the bottom surface of the cylindrical container at a predetermined interval is provided at the opening of the cylindrical container. In this way, the wires are supported so as to stand in the cylindrical container, and the epoxy resin is filled in the container in which the wires are installed.

After the resin material was filled in the cylindrical container, it was degassed in vacuum and gradually heated to a maximum temperature of 170 ° C. for about 5 hours.
Keep in a dry nitrogen atmosphere. As a result, the resin material is hardened, and after hardening, the block body 48 is taken out from the cylindrical container. As described above, the block body 48 is obtained by embedding the lead-tin eutectic alloy wire in the resin material 46 of epoxy resin. The obtained block body 48
Is cut into a sheet of about 200 μm to obtain a joining sheet body 50.

When a multilayer wiring board is produced using the joining sheet 40, the joining surface of the wiring board 14 and the joining sheet 40 are aligned, and the joining sheet 40 is used on the wiring board 14.
It suffices to sandwich and pressurize and heat to integrate them. The wiring board 14 is adhered by the resin 44 of the bonding sheet 40, and the wiring pattern 12 is electrically connected by the low melting point metal 42. Since the bonding sheet 40 uses a wire of a low melting point metal as a low melting point metal for electrically connecting the wiring pattern 12, a void is generated in the bonding portion as in the case of using a solder paste, or the bonding is performed at the time of bonding. There is an advantage that the volume change of the part is prevented from occurring and a reliable electrical connection is made.

A low melting point metal 42 is attached to the joining sheet 40.
When arranging, the low melting point metal 42 can be provided according to the arrangement of the wiring pattern 12 of the wiring board 14 to be joined, and it is assumed to be used for general purposes as shown in FIGS. Then, the low melting point metal 42 may be provided in a configuration in which the low melting point metal 42 is arranged at regular intervals.

[0032]

As described above, since the multilayer wiring board according to the present invention is formed by integrally connecting the wiring boards having a plurality of wiring patterns formed thereon by electrically connecting the wiring patterns to each other, a defect occurs. It is possible to obtain a highly reliable product by reducing the rate and improving the manufacturing yield. Further, since it is formed by joining the wiring substrates having the core substrate, it is possible to provide a product having sufficient strength and excellent flatness and the like. Further, since the wiring boards having several wiring patterns formed thereon are joined to each other, the overall manufacturing process is simplified, the manufacturing is facilitated, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a multilayer wiring board according to the present invention.

FIG. 2 is a cross-sectional view showing a method of manufacturing a wiring board used for manufacturing a multilayer wiring board.

FIG. 3 is a cross-sectional view showing a method of manufacturing a wiring board used for manufacturing a multilayer wiring board.

FIG. 4 is a cross-sectional view showing a method of manufacturing a wiring board used for manufacturing a multilayer wiring board.

FIG. 5 is a cross-sectional view showing a method of manufacturing a wiring board used for manufacturing a multilayer wiring board.

FIG. 6 is a cross-sectional view showing a method of manufacturing a wiring board used for manufacturing a multilayer wiring board.

FIG. 7 is a cross-sectional view of a joining sheet used for manufacturing a multilayer wiring board.

FIG. 8 is a perspective view of a block body forming a joining sheet.

FIG. 9 is a perspective view of a joining sheet body cut out from a block body.

[Explanation of symbols]

 10, 10a, 10b Core substrate 12 Wiring pattern 14, 14a, 14b Wiring substrate 16 Substrate bonding layer 18a, 18b Wiring pattern 20 Through hole 22 Electrical insulating layer 24 Via hole 26 Conducting portion 30 Connecting portion 40 Bonding sheet 42 Low melting point Metal 44 Resin 46 Resin material 48 Block body 50 Bonding sheet body

Claims (7)

[Claims] 1. A plurality of wiring boards, each having wiring patterns formed on at least one surface of a core board, joining the wiring boards between the wiring boards and electrically connecting the wiring patterns to each other. A multilayer wiring board, wherein the multilayer wiring board is integrally laminated via a substrate bonding layer. 2. The board bonding layer is constituted by a bonding sheet body in which a low melting point metal for electrically connecting the wiring patterns is supported by a resin for bonding the wiring board. Multilayer wiring board. 3. The multilayer wiring board according to claim 1, wherein the wiring board has wiring patterns formed on both surfaces of the core substrate. 4. The multilayer wiring board according to claim 1, wherein the core board is a printed board having a plurality of wiring patterns electrically connected between layers. 5. The multilayer wiring board according to claim 1, 2 or 3, wherein the core board is a ceramic board in which a plurality of wiring patterns electrically connected between layers are formed. 6. The multilayer wiring board according to claim 1, wherein the wiring board has a plurality of wiring patterns formed on the surface of the core substrate by a build-up method. 7. The multilayer wiring board according to claim 1, wherein the wiring board has a plurality of wiring patterns formed on the surface of the core board by a thin film method.