JPH0211032B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multilayer wiring board, and in particular to a printed wiring board on which multi-terminal electronic components (hereinafter referred to as components) having a large number of closely spaced connection pins such as flat packages and pin grid ICs are mounted. Regarding conductive pads.

Conventionally, conductive pads provided on multilayer wiring boards are provided on the outermost layer of the multilayer wiring board, so when mounting components with connection pins arranged in three or more rows, the circuit pattern is placed on the outermost layer. is concentrated. Therefore, even if part of the circuit pattern is passed through the inner layer to avoid concentration, countermeasures such as providing a layer having conductive pads only as lands on the outermost layer are required.

At the same time, through-hole plating and the like were required to connect the internal circuit pattern to the external conductive pad.

An object of the present invention is to provide a multilayer wiring board having conductive pads that eliminates the need for connection between such internal circuit patterns and external conductive pads.

According to the present invention, a conductive pattern is provided on an insulating plate to expose a part of each side of the laminated wiring board in a stepwise manner, and a conductive pad is provided on the exposed part to connect the conductive pattern. A multilayer wiring board is obtained.

Embodiments of the present invention will be described below with reference to FIGS. 1a and 2b and FIGS. 2a and 2b.

Embodiment 1 Figures 1a and 1b show an embodiment of the present invention, in which a conductive pad suitable for mounting terminals of flat packages, chip carriers, etc. by pressure welding, welding, soldering, etc. is used on the surface. This is a multilayer wiring board with

It is disposed so as to be exposed from the rectangular cutout of the second insulating layer 3. Therefore, the circuit pattern 2 connects the conductive pads 4 of the third layer to the conductive pads 4 on the third insulating layer 1 in such a way that they can be connected to some of the pins of components such as flat packages and chip carriers.
is not exposed to the outside due to the second insulating layer 3. Similarly, the second layer conductive pad 4 is connected to the first layer so that it can be connected to some of the remaining terminals of the component.
The insulating layer 5 is disposed at the same position so as to be exposed from a cutout portion that is larger than the third insulating layer.

Therefore, the circuit pattern 2 on the second insulating layer 3 also has a structure hidden by the first insulating layer 5 on the surface, and therefore the conductive pads on each of the first to third insulating layers are placed around the step-like recess. It is provided in an exposed shape on each staircase surface along the line.

Note that even when the number of layers is further increased, they can be provided in a stepwise manner in the same way.

Embodiment 2 Similarly, Figures 2a and 2b show multilayer wiring boards in which component terminals are mounted and through mounting holes are provided in the conductive pads so that plug-in type components such as pin grid arrays can be mounted. This is an example of the following.

In the case of the embodiment shown in FIG. 2, the part of the conductive pad 4 is provided in a step-like manner, which is exactly the same as in the embodiment 1 shown in FIG. 4 is provided with component mounting holes 6 that do not penetrate to the back surface and component mounting holes 6 that penetrate to the back surface. Component mounting hole 6 that does not penetrate to the back side
can be easily obtained by providing a mounting hole at the center of the pad of the required layer before stacking each layer. Furthermore, in this case, it is also possible to use a blind through hole.

As described above, the present invention has the following effects.

(i) Since the conductive pad formed in connection with the internal conductive layer pattern is directly exposed to the outside, there is no need to provide a connection part to the external conductive pad by through-hole plating or the like.

(ii) Since depressions are formed on the surface of the multilayer wiring board, there is an advantage that the protrusion of the mounted components can be reduced and the components can be firmly fixed.

It should be noted that any of the embodiments can be used not only for mounting ICs but also for connecting and mounting electronic components having similar connection pin shapes.

Moreover, it goes without saying that not only a single component but also a plurality of components can be mounted simultaneously.

[Brief explanation of drawings]

FIGS. 1a and 1b are a plan view and a sectional view, respectively, showing enlarged main parts of a first embodiment of the multilayer wiring board of the present invention. FIGS. 2a and 2b are a plan view and a sectional view, respectively, of the main parts of a second embodiment of the present invention. 1...Third insulating layer, 2...Circuit pattern, 3...
...second insulating layer, 4...conductive pad, 5...first insulating layer, 6...component mounting hole (hole).

Claims (1)

[Claims] 1. A wiring board laminated with a conductive pattern provided on an insulating plate has a step-like recess, a part of the conductive pattern is exposed on each step surface, and the conductive pattern has a width wider than the width of the conductive pattern. A multilayer wiring board characterized in that a pad is provided along the periphery of the stepped recess and connected to the conductive pattern.