JPH05251869A - Multilayered printed wiring board - Google Patents

Abstract

PURPOSE:To easily detect solder bridges among leads after a flat IC has been mounted, in a multilayered printed wiring board with the pads for mounting flat IC parts. CONSTITUTION:An inner-layer copper foil 4 in an area for forming pads 2 is provided with a polygonal clearance 3. Thus, after a flat IC has been mounted, a printed wiring board is applied with light transmittance to detect any solder bridge among the leads. In addition, electrical supply capacity can be secured for a conductive land connected just beneath the flat IC with an aid of polygonal clearance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board in which an inner layer copper foil and an insulating substrate are laminated in multiple layers.

[0002]

2. Description of the Related Art In recent years, surface mounting of electric parts has progressed, and in multilayer printed wiring boards for mounting them, the number of multilayer printed wiring boards having pads for mounting electric parts is increasing. Conventionally, in this type of multilayer printed wiring board, the inner layers are formed by copper foil-like layers over the entire surface as power supply layers and ground layers.

[0003]

FIG. 3 is a plan view of an inner copper foil of a multilayer printed wiring board. In the power supply layer and the ground layer of the inner copper foil 14, the clearances 13 and the conductive lands 8 are provided for the through holes provided in the multilayer printed wiring board 11 depending on the necessity of connection. This allows
Connection and disconnection are made to the power supply layer and the ground layer. In FIG. 3, the copper foil portion is shaded for easy understanding.

FIG. 4A is a plan view showing an example of a conventional multilayer printed wiring board, and FIG. 4B is a sectional view taken along line BB. However, in the conventional multilayer printed wiring board, unlike the through hole for the pad 2 for surface mounting, as shown by the dashed diagonal line in FIG.
As shown in (b), the entire surface was the copper foil-shaped inner layer copper foil 14.

FIG. 5 is a plan view of the multilayer printed wiring board of FIG. 4 on which the flat IC is mounted. 5, the hatched portion of the broken line shows the inner layer copper foil 14 of FIG. There is a problem that a solder bridge 7 is easily generated between the adjacent leads of the leads 6 of the flat IC 5 mounted on the surface pad portion of the multilayer printed wiring board 1. An object of the present invention is to make a multi-layer printed wiring board transparent to light so that a pad portion may be damaged and flat I
It is an object of the present invention to provide a multilayer printed wiring board in which a solder bridge between leads of C can be easily found.

[0006]

In order to achieve the above object, a multilayer printed wiring board according to the present invention is a multilayer printed wiring board having pads for mounting flat IC components, wherein an inner copper foil portion corresponding to the pad position is provided. It is configured by providing a polygonal clearance.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings. 1 (a) and 1 (b) are a plan view and an AA sectional view showing an embodiment of a multilayer printed wiring board according to the present invention. The polygonal clearance 3 is formed in the inner layer copper foil 4 corresponding to the formation area of the pad 2 provided on the surface of the multilayer printed wiring board 1a.
Is provided.

FIG. 2 is a plan view of the flat printed circuit board of FIG.
It is a top view when C is mounted. When the flat IC 5 is mounted on the multilayer printed wiring board 1 as shown in FIG. 2, the flat IC soldered to the pad 2 of the multilayer printed wiring board
When the solder bridge 7 is generated between the leads 6 of the No. 5 lead, the clearance 3 is provided in the inner layer copper foil 4 shown by the broken line in FIG. I'm getting better.

[0009]

As described above, the present invention provides a multilayer printed wiring board having pads for mounting flat ICs,
By providing a clearance in the inner copper foil corresponding to the pad position, it is possible to easily find a defect in the pad portion and a solder bridge between the leads of the flat IC by transmitting the printed wiring board to light. Further, by forming the clearance in a polygonal shape, it is possible to secure the electric supply capacity to the conductive land connected directly under the flat IC.

[Brief description of drawings]

1A is a plan view showing an embodiment of a multilayer printed wiring board according to the present invention, and FIG. 1B is a sectional view taken along line AA.

FIG. 2 is a plan view of the multilayer printed wiring board of FIG. 1 when a flat IC is mounted.

FIG. 3 is a plan view of an inner layer copper foil of a multilayer printed wiring board.

FIG. 4A is a plan view showing an example of a conventional multilayer printed wiring board, and FIG. 4B is a sectional view taken along line BB.

5 is a plan view of the printed wiring board of FIG. 4 when a flat IC is mounted.

[Explanation of symbols]

 1, 11 ... Multilayer printed wiring board 2 ... Pads 3, 13 ... Clearance 4, 14 ... Inner layer copper foil 5 ... Flat IC 6 ... Lead 7 ... Solder bridge 8 ... Conductive land

Claims (1)

[Claims] 1. A multilayer printed wiring board having a pad for mounting a flat IC component, wherein an inner copper foil portion corresponding to the pad position is provided with a polygonal clearance.