JPH0758825B2 - Wiring board - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a metal-based wiring board used for assembling a semiconductor device, and particularly used for assembling a semiconductor chip (bare chip) having no outer packaging. To be

[Technical background of the invention]

There is a metal-based wiring board having a structure whose cross section is shown in FIG. In the figure, 101 is an aluminum plate having a plate thickness of, for example, 2 mm, and a layer having a layer thickness of 0.16 mm is formed on the one main surface through an electrically insulating layer 102 of a resin, and is formed into a desired pattern with a thickness of 0.035 mm by etching. A wiring pattern layer including a conductive thin layer 103a, and an example of a plated metal layer 103b having a thickness of several microns, which is formed by laminating electrolytic plating of gold or silver on the conductive thin layer.
103 is formed. The metal-based wiring board 100 thus formed is shown in front view in FIG. 4a. In the figure, the wiring pattern layer 103b has pad portions that are widened in a square shape face each other inside the substrate surface, and as shown in the circuit diagram shown in FIG. To do.

When forming the above-mentioned substrate, since it is necessary to electrically connect mutually electrically separated wiring patterns as an integral electrode to the electrolytic plating for forming the plated metal layer, as shown in FIG. A large-sized board 200 is prepared, and a plurality of separated wiring patterns of the wiring board 100 on the inner side indicated by broken lines in the drawing are drawn to the outer area of this board to form a conduction pattern 210 and a plating electrode 211 for common connection. To do. Then, when the electrolytic plating is completed, it is cut along with the conduction pattern at the broken line portion.

[Problems of background technology]

As described above, a wiring board that uses electroplating to form a wiring pattern layer allows a plating current to flow, so that the patterns of multiple conductive thin layers (copper foils) are commonly connected, making the wiring one size larger than the desired wiring board. The board is prepared, and the wiring pattern of the desired substrate is pulled out to the common connection, but when the electrolytic plating is completed, the outer area of the wiring board and the conduction pattern are cut, but this cutting is generally performed by pressing. Punched out with. This cutting causes "drip" on the end surface (broken line portion shown in FIG. 2a) of the substrate, and the thickness of the electrically insulating layer at that portion becomes uneven. This has caused a serious problem of causing dielectric breakdown.

[Object of the Invention]

In view of the above conventional problems, the present invention provides an improved structure for eliminating dielectric breakdown at the end surface of a wiring board.

[Outline of Invention]

A wiring board ( 10 ) according to the present invention is a conductive substrate ( 10 ).
1) A conductive thin layer (103a) formed on top of an electrically insulating layer (102) and a plated metal layer (103b) laminated and deposited thereon.
The wiring pattern layer (103) consisting of both layers (103a, 10
A hole (11) continuously penetrating through 3b) in the thickness direction is separated from the wiring pattern on the end face of the substrate to prevent dielectric breakdown at the end face of the substrate. Further, in the next invention, the wiring pattern layer exposed in the hole is provided with an electric insulation coating layer (12) such as a photoresist, and a large proof stress against dielectric breakdown can be obtained.

Example of Invention

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In the description, parts that are the same as those in the related art are denoted by the same reference numerals as those in the related art and will not be described.

FIG. 1a is a front view of the wiring board 10 , in which 11,11 ... Are holes provided for cutting the wiring pattern layer 103, and these holes are surrounded by the broken line in FIG. 1a in FIG. 1b. As shown in the cross section along the wiring pattern of the part shown, a drill slightly larger than the wiring pattern width so that the wiring pattern of the planned cutting portion is completely cut, for example, a diameter of 1 for a wiring pattern with a width of 0.5 mm.
It was removed with a mm drill until it reaches at least the electrically insulating layer 102. This hole may be a countersink, but it does not have to be a through hole that penetrates to the base.

Next, FIG. 1c shows the hole of the second invention. As shown in the figure, 11 is the same as the hole disclosed in the first invention, but the end surface of the wiring pattern layer 103 exposed in the hole by coating the inner surface of the hole with the electric insulation coating layer 12 The electrical insulation between the substrate 101 and the substrate 101 is improved. Solder resist is suitable for the electric insulation coating layer, which is formed by depositing from the inner surface of the hole to the upper surface of the peripheral edge thereof, drying and curing.

Next, FIGS. 2A to 2C show the formation of this wiring board in a rough order of steps. FIG. 3A shows a wiring board surrounded by a broken line.
10 is provided on a large-sized substrate 200 having a conductive pattern 210 for forming a plated metal layer on the outside thereof. At this stage, both the wiring pattern and the conductive pattern are the conductive thin layer 103a formed by etching on the copper foil, and all the plural wiring patterns are led out to be connected to the conductive pattern 210 and connected to the plating electrode 211. There is.

Then, electroplating is performed and a gold plating layer as an example is applied to the wiring pattern, as shown in FIG. 2B. In this case, since the conductive pattern 210 does not need to be plated with gold, it is advisable to avoid the plating electrode and apply a solder resist before electrolytic plating. After that, drill a hole to make a hole.
Provide 11,11 ...

Next, the broken line portion of FIG. 2B is cut by press punching to obtain the wiring board 10 shown in FIG. 2C (corresponding to that shown in FIG. 1).

〔The invention's effect〕

According to the present invention, a circuit pattern portion (peripheral edge portion of the wiring board) unnecessary as a circuit, whose dielectric strength is lowered due to "drip" at the time of press cutting, is partially cut by drilling to take measures. As a result, the withstand voltage between the wiring pattern and the metal substrate is dramatically improved, and there is a remarkable effect that a short circuit due to contamination, adhesion of foreign matter, etc. can be prevented. This is because punching by press work causes a "dag" when a large force is applied to the wiring pattern toward the substrate.
This is because the present invention is a method of cutting with a drill, and since the force for applying this to the wiring pattern in the direction of the substrate is extremely small, the thickness of the electrical insulating layer can be completely maintained.

If the solder resist coating on the surface of the substrate is also used, the withstand voltage becomes 5 kV or more when the solder resist coating thickness is about 0.3 mm. Furthermore, the present invention has the advantage that it can be achieved mainly by drilling, and even if a solder resist coating is added thereto, it is extremely simple to carry out. Further, according to the present invention, even after a circuit pattern is formed and the pattern causes a short circuit between the circuit board and the substrate due to press cutting applied to the end of the circuit board, a short circuit with the circuit pattern can be prevented. Moreover, there is a remarkable advantage that its implementation is extremely simple and can be achieved by drilling, for example.

[Brief description of drawings]

FIG. 1a is a front view of a wiring board according to an embodiment of the present invention, and FIG. 1b is a perspective view showing a main section of the first invention in a partial cross section.
FIG. 3C is a perspective view with a partial cross-section showing an essential part of the second invention, and FIGS. 2A to 2C are front views of the substrate, all of which show the formation of the wiring substrate of the invention in the order of steps. 4A is a front view of a conventional wiring board, FIG. 4B is a circuit diagram of this wiring board, and FIG. 5 is a cross-sectional view of a cut portion of the end surface of the wiring board. 10 , 100 ...... Wiring board 11 …… Hole 12 …… Electrical insulation coating layer 101 …… Metal substrate 102 …… Electrical insulation layer 103 …… Wiring pattern layer 103a …… Conductive thin layer 103b …… Plating metal layer

Claims (2)

[Claims] 1. A wiring pattern layer comprising a conductive thin layer formed on a conductive substrate with an electrically insulating layer interposed therebetween, a plated metal layer laminated and deposited on the thin layer, and a part of the wiring pattern layer. A wiring board provided with a hole that is continuous in the thickness direction of both layers and penetrates in the entire width direction to electrically cut the wiring pattern layer. 2. A wiring pattern layer comprising a conductive thin layer formed on a conductive substrate via an electrically insulating layer, a plated metal layer laminated on the thin layer, and a part of the wiring pattern layer. A hole for electrically cutting the wiring pattern layer that penetrates both layers in the thickness direction and penetrates the entire width direction, and an electrically insulating coating layer that covers the wiring pattern layer exposed in the hole are provided. Wiring board.