JP2006324377A - Printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board in which stripping strength of a substrate and a component mounting land can be enhanced drastically and good soldering can be performed with extremely high reliability. <P>SOLUTION: A via is formed directly under a component mounting land formed larger than the soldering area. On the component mounting land, solder resist is removed over an area equal to the soldering area and rides over the periphery of the component mounting land or a part thereof. Overriding amount is set to absorb the slippage for the circuit pattern when the solder resist is formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printed wiring board used in various electronic devices such as a personal computer, a mobile communication telephone, and a video camera.

  In recent years, as electronic devices have higher functionality and higher density, electronic components are becoming increasingly smaller, highly integrated, faster, and multi-pinned.

  For this reason, printed circuit boards are becoming increasingly low-dielectric constant, thin, and lightweight. At the same time, the mounting components are designed to meet the demands for miniaturization while increasing the number of pins. In addition to mold packages, surface-grid mounting packages have been put into practical use and tend to be denser, and on the other hand, reliability and repairability during mounting have been required.

  A conventional printed wiring board will be described below. 3A and 3B are diagrams showing a conventional printed wiring board. 3A and 3B, 11 is a component mounting land, and 12 is a solder resist.

  The printed wiring board configured as described above will be described in detail below. The component mounting lands 11 are formed at the same time when a circuit pattern is formed on the front and back sides of the double-sided printed wiring board or the outermost metal layer of the multilayer printed wiring board by using means such as etching. Next, a short circuit is prevented by forming a solder resist 12 in an unnecessary portion when mounting a component by soldering or the like. At this time, when the solder resist 12 rides on the component mounting land 11, the mounting area of the component mounting land 11 is reduced, which hinders good soldering.

  Therefore, when the solder resist 12 is formed in order to prevent this, the part on the component mounting land 11 has a clearance with respect to the component mounting land 11 in advance and is designed with a shape larger than that of the component mounting land 11. Even if a slight deviation from the circuit pattern occurs at the time of forming 12, it can be absorbed. Here, as shown in FIGS. 3A and 3B, there are various shapes such as a circular shape and a quadrangular shape as the removed portions of the component mounting land 11 and the solder resist 12.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP-A-11-145605

  However, in the above-described conventional printed wiring board, the clearance between the component mounting land 11 and the solder resist 12 tends to decrease as the density increases, and therefore, between the circuit pattern and the solder resist 12. Even when a slight deviation occurs, there is a problem that the soldering area decreases due to the climbing and tends to hinder good soldering.

  Further, when the component mounting land 11 is made small in order to obtain a sufficient clearance while maintaining a high density, there is a problem that the component mounting land 11 is peeled off from the base material depending on a handling method such as repair.

  The present invention solves the above-mentioned conventional problems. Even if a slight deviation occurs between the circuit pattern and the solder resist, a sufficient soldering area is secured, and good soldering is achieved with high reliability. An object of the present invention is to provide a printed wiring board that can be used.

  In order to achieve this object, the printed wiring board of the present invention has a configuration in which a solder resist is formed on or around a part mounting land in a part mounting land of a circuit pattern.

  The invention described in claim 1 of the present invention is such that a solder resist is formed so as to run on the periphery or part of the component mounting land in the component mounting land of the circuit pattern. The solder resist is exposed to all portions of the solder resist removal portion formed thereon, and the soldering area is equal to the area of the solder resist removal portion. Even if some deviation occurs in the circuit pattern during solder resist formation, the area of the exposed part of the component mounting land should be designed in advance so that the amount of deviation can be absorbed by the amount of solder resist on the component mounting land. Is always kept constant, and the soldering state is always kept constant. In addition, the component mounting land has an effect that the adhesive force to the base material is reinforced by the solder resist that runs around the component mounting land, and the base material and the component mounting land can be prevented from peeling off.

  According to a second aspect of the present invention, a through hole is formed in a glass woven fabric base material impregnated with an epoxy resin, a conductive paste is filled in the through hole, and both surfaces of the porous base material are heated and pressurized. Solder resist is formed so as to run around or part of the component mounting land of the circuit pattern formed by the laminated metal layer. Through this structure, through holes are formed in the glass woven epoxy base material to conduct electricity. After filling the conductive paste, the pattern wiring is densified by heating and pressurizing the substrate, and at the same time, the land peel strength, which has been a weak point of the prior art, can be improved for the reason described in the first aspect.

  The invention according to claim 3 is the printed wiring board according to claim 1 or 2 in which a via made of conductive paste is formed immediately below the component mounting land. By forming a via directly below, it is not necessary to route an extra circuit pattern, and the wiring density is greatly improved, and the land peeling strength can be improved at the same time.

  According to this configuration, there is provided a printed wiring board that can secure a sufficient soldering area and can perform good soldering with high reliability even if a slight deviation occurs between the circuit pattern and the solder resist. can get.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. 1A to 1C are views showing a printed wiring board in an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the printed wiring board in the embodiment of the present invention. In FIGS. 1A to 1C and FIG. 2, the solder resist 2 runs on the periphery of the component mounting land 1, so that even if a slight deviation occurs between the two, the amount of ride up is within this amount. The component mounting land 1 can be absorbed and the exposure amount of the component mounting land 1 is always kept constant, and at the same time, the component mounting land 1 can be reinforced by the solder resist 2 mounted on its periphery.

  Next, specific examples of the present invention will be described. 1A to 1C and FIG. 2, 1 is a component mounting land, 2 is a solder resist, 3 is a via, 4 is a base material, and 5 is a circuit pattern.

  The operation of the printed wiring board configured as described above will be described below. As shown in FIGS. 1A to 1C, the component mounting land 1 is formed larger than a necessary predetermined mounting area, and the predetermined mounting area is formed on the component mounting land 1. By removing the solder resist 2, the component mounting land 1 can be exposed by a predetermined mounting area. As a result, the solder resist 2 rides on the entire periphery or a part of the component mounting land 1, and even if a slight deviation occurs between the two, the component mounting land 1 can be absorbed in this riding amount. The exposure amount is always kept constant. At the same time, the component mounting land 1 can be reinforced by the solder resist 2 that rides around the component mounting land 1, and the peel strength between the substrate 4 and the component mounting land 1 can be improved.

  Also, as shown in FIG. 2, a glass woven fabric base material impregnated with an epoxy resin is used for the base material 4 and a through hole is formed in the base material 4 and filled with a conductive paste, and then the base material 4 is heated and pressurized. By repeating the formation of the via 3 and the formation of the circuit pattern 5 thereafter, it is possible to electrically connect only between arbitrary layers without the need for through holes, and at the same time, the wiring is densified and at the same time the periphery of the component mounting land 1 The land peel strength, which has been a weak point of the prior art, can be improved for the above reason by riding the solder resist 2 on the surface.

  Furthermore, by forming a via 3 immediately below the component mounting land 1, it is possible to make an electrical connection from the component mounting land 1 to another layer without being routed to other parts by a circuit pattern, and extremely increase the wiring density. At the same time, the land peel strength, which has been a weak point of the prior art, can be improved for the above reason by riding the solder resist 2 around the component mounting land 1.

  As described above, according to the present embodiment, by mounting the solder resist 2 around the component mounting land 1, even if a slight deviation occurs between the two, the component mounting is performed by absorbing the amount within this amount. The exposure amount of the land 1 is always kept constant, and at the same time, the peeling strength between the base material 4 and the component mounting land 1 can be improved by reinforcing the component mounting land 1 with the solder resist 2 mounted on the periphery thereof. It is possible to provide a printed wiring board capable of performing reliable soldering with high reliability.

  In the embodiment of the present invention, the shape of the component mounting land 1 and the shape of the removal portion of the solder resist 2 are circular or quadrangular, but other shapes and combinations thereof may be used.

  As described above, according to the present invention, by exposing the solder resist around the component mounting land, even if a slight deviation occurs between the two, the amount of exposure of the component mounting land is always absorbed. It is possible to improve the peel strength between the substrate and the component mounting land by reinforcing the component mounting land with the solder resist that runs around the component mounting land at the same time, and to perform good soldering with high reliability. A possible printed wiring board can be realized.

(A)-(c) The figure which shows the printed wiring board in embodiment of this invention Sectional drawing of the printed wiring board in embodiment of this invention (A), (b) The figure which shows the conventional printed wiring board

Explanation of symbols

1 Component mounting land 2 Solder resist 3 Via 4 Base material 5 Circuit pattern

Claims (3)

A printed wiring board that is formed so that a solder resist runs on or around a part mounting land in a circuit pattern component mounting land. A through-hole is formed in a glass woven fabric base impregnated with an epoxy resin, a conductive paste is filled in the through-hole, and a circuit pattern formed by a metal layer bonded by heating and pressurizing both surfaces of the porous base material. The printed wiring board according to claim 1, further comprising a solder resist formed so as to run around a part mounting land or a part thereof. The printed wiring board according to claim 1, wherein a via made of a conductive paste is formed immediately below the component mounting land.

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