JPH0271585A - Surface mounting printed wiring board - Google Patents

Abstract

PURPOSE:To make the width of a resist between pads sufficient to assure the reliability of the resist by setting the form of each copper foil pad for mounting components to be rather large and, in the case where the resist is applied on the copper foil pads, causing only a form which is necessary for mounting components and is smaller than each copper foil pad to be free from application of the resist at a part corresponding to a component mounting part. CONSTITUTION:Each copper foil pad 3 is formed in such a way that it is larger than a form which is necessary for mounting components of the copper foil pad and only a form required for mounting the above components is free from the application of a resist and a part not applied with the resist where the resultant copper foil 3 appears on the surface is used as the part 6 for mounting the components.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface mount printed wiring board, and particularly to a surface mount component having a copper foil pad portion for mounting surface mount components.

[Conventional technology]

Conventionally, in this type of surface mount printed wiring board, the resist on the copper foil pad for component mounting was printed at a size that took into consideration the positional deviation of the resist from the copper foil pad, so that the resist did not cover the copper foil pad. It had been.

[Problem to be solved by the invention]

The above-mentioned conventional surface mount printed wiring board is based on the assumption that resist escape does not touch the copper foil pads, so the components become denser, the spacing between the copper foil pads becomes narrower, and copper is deposited in the gaps between the copper foil pads. If you try to print the resist so that it does not cover the foil pad, the width of the printed resist becomes so thin that its reliability cannot be guaranteed. In other words, the resist for printed wiring boards has a disadvantage in that the adhesiveness of the resist deteriorates and it becomes easy to peel off. In addition, even if the reliability of the printed wiring board is improved by increasing the width of the resist, the resist will shift due to positional accuracy problems, and the resist will cover the pads, which will hinder component mounting. There is a drawback that. Furthermore, with conventional printed wiring boards, if resisting is impossible as described above, it is conceivable that resisting is not done between the copper foil pads, but this may cause a short circuit between the silver foil pads due to solder during component mounting. This also becomes a problem.

[Means to solve the problem]

The surface mount printed wiring board of the present invention has copper foil pads for component mounting on the surface layer that have a larger shape than necessary for component mounting, and copper foil pads necessary for mounting in areas where the copper foil needs to be exposed during component mounting. It has a resist formed by printing a resist material with a window in the shape.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a plan view showing one embodiment of the present invention. In FIG. 1, the surface mounting printed wiring board 1 of this embodiment has a copper foil pad 3 for mounting components on the upper surface, a wiring pattern 4 connected to the copper foil pad and the through hole, a land 5 attached to the through hole, etc. are formed by a copper pattern, and these parts are collectively indicated by diagonal lines downward to the right in FIG. At this time, the copper foil pad 3 for component mounting is formed to be larger than the shape actually required for component mounting.

A resist material is finally printed on the surface mount printed wiring board 1 for the purpose of protecting the copper foil circuit, and the resist printed on this board is shown by diagonal lines 2 in FIG.

When printing this resist, the resist is removed so that it does not cover copper foil pads or through-hole lands necessary for component mounting. For the through-hole land 5 shown in FIG. 1, resist relief is provided in a circle slightly larger than the diameter of the land. Similarly, resist relief is performed for the copper foil pad, but in one embodiment of the present invention, the pad is formed larger than the shape required for the copper foil pad component mounting, so the resist relief is limited to the shape necessary for component mounting. Let be the relief shape. The part where the copper foil is finally visible on the surface due to resist escape is used as the part for mounting the component.

If the above method is used, even if a positional shift occurs during resist printing, the copper foil pad underneath is formed slightly larger, so the area necessary for the copper foil pad can be secured. Further, the width of the resist between the pads does not require consideration of the shape of the copper foil or the misalignment of the resist, and a sufficient width can be secured to ensure a certain level of reliability.

〔Effect of the invention〕

As explained above, in the present invention, the shape of the copper foil pad for component mounting on the surface mount printed wiring board is set to be larger, and with respect to the resist printed thereon, the part corresponding to the component mounting part is made larger than the copper foil pad. By removing the resist in the shape necessary for mounting small components, we can secure the copper foil pad area necessary for mounting even if the resist printing is misaligned, and we can also secure the resist width between the pads to ensure reliability. There is a guaranteed effect.

FIG. 1 is a plan view showing an embodiment of the present invention.

DESCRIPTION OF SYMBOLS 1...Surface mount printed wiring board, 2...Resist for circuit protection, 3...Copper foil pad, 4...Wiring pattern, 5...Through hole land, 6...Copper Component mounting area on foil pad (part without resist).

Claims (1)

[Claims] In a surface mount printed wiring board that has copper foil pads on the top surface for mounting components, the shape of the copper foil pads is made larger than the shape required for mounting, and the resist formed on this is used for mounting components. A surface mount printed wiring board characterized in that resisting is performed in a shape with a window opened as much as necessary, and finally the copper foil portion not covered with the resist is used as a copper foil pad for mounting components.