JPH11145605A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board wherein, even some displacement occurs between a circuit pattern and a solder resist, a sufficient soldering area is secured for good soldering with high reliability. SOLUTION: A solder resist 2 rides over around a mounting land 1 so that some displacement between them is caucelled in the overlap amount for constant exposure amount of the mounting land 1, at the same time, the mounting land 1 is reinforced by the solder resist 2 overlapping raround it for improved anti- peeling strength between a base material and the mounting land 1, thus a printed wiring board wherein good soldering is realized with high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board used for various electronic devices such as a personal computer, a mobile communication telephone, and a video camera.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become higher in function and higher in density, electronic components have tended to become smaller, more highly integrated, operate at higher speeds, and have more pins.

[0003] For this reason, printed wiring boards are becoming more and more low dielectric constant, thinner and lighter, and at the same time, the mounting parts are more compact in response to the increase in the number of pins. In addition to the peripheral terminal mounting type package, a surface lattice mounting type package has been put into practical use, and the density has tended to increase. On the other hand, reliability and repairability during mounting have been required.

[0004] A conventional printed wiring board will be described below. FIGS. 3A and 3B are views showing a conventional printed wiring board. 3A and 3B, reference numeral 11 denotes a component mounting land, and reference numeral 12 denotes a solder resist.

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

To prevent this, when the solder resist 12 is formed, a portion on the component mounting land 11 is designed to have a clearance in advance with respect to the component mounting land 11 and to be designed in a shape larger than the component mounting land 11. In addition, even if a slight deviation from the circuit pattern occurs when the solder resist 12 is formed, the deviation can be absorbed. Here, the shape of the removed part of the component mounting land 11 and the solder resist 12 is circular as shown in FIGS.
There are various shapes such as squares.

[0007]

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 of the printed wiring board further increases. Even when a slight displacement occurs between the pattern and the solder resist 12, there is a problem that the soldering area is reduced due to the climb and the soldering tends to be hindered.

If the component mounting land 11 is made small in order to obtain a sufficient clearance while maintaining a high density, the component mounting land 1 may be reduced depending on a handling method such as repair.
1 had a problem that it peeled off from the substrate.

The present invention solves the above-mentioned conventional problems. Even if a slight displacement occurs between a circuit pattern and a solder resist, a sufficient soldering area is ensured and good soldering is performed with high reliability. It is an object of the present invention to provide a printed wiring board which can be performed by the property.

[0010]

In order to achieve this object, a printed wiring board according to the present invention has a structure in which a solder resist is formed on a component mounting land of a circuit pattern so as to ride around the component mounting land or a part thereof. have.

[0011] According to this configuration, even if a slight deviation occurs between the circuit pattern and the solder resist, a printed wiring that can secure a sufficient soldering area and perform good soldering with high reliability. A plate is obtained.

[0012]

According to a first aspect of the present invention, in a component mounting land of a circuit pattern, a solder resist is formed so as to ride around or part of the component mounting land. As a result, the component mounting land is exposed to all portions of the removed portion of the solder resist formed thereon, and the soldering area is equal to the area of the removed portion of the solder resist. Even if there is some deviation from the circuit pattern during the formation of the solder resist, 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 riding on the component mounting land. Is always kept constant, and the soldering state is always kept constant. Further, the component mounting land has an effect that the adhesive strength to the base material is reinforced by the solder resist running on the periphery thereof, so that separation of the component mounting land from the base material can be prevented.

[0013] According to a second aspect of the present invention, there is provided a porous base material made of an aromatic polyamide impregnated with an epoxy resin, wherein a through-hole is formed, and the through-hole is filled with a conductive paste. A solder resist is formed so as to ride on or around a component mounting land of a circuit pattern formed by a metal layer bonded by heating and pressing on both sides of the base material. The printed wiring board is made to have a low dielectric constant by the aromatic polyamide material, and the pattern wiring is made dense by forming a through hole in the compressed porous substrate, filling the conductive paste, and then heating and pressing the substrate. At the same time, there is an effect that the land peel strength, which is a conventional weak point, can be improved for the reason described in the function of claim 1.

According to a third aspect of the present invention, a via made of a conductive paste is formed immediately below a component mounting land.
Alternatively, the printed wiring board according to claim 2 is formed, and with this configuration, it is not necessary to route extra circuit patterns by forming vias directly below the component mounting lands, thereby greatly improving the wiring density. In addition, it has the effect that the land peel strength can be further improved at the same time.

An embodiment of the present invention will be described below with reference to FIGS. FIGS. 1A to 1C are views showing a printed wiring board according to an embodiment of the present invention.
FIG. 2 is a sectional view of the printed wiring board according to the embodiment of the present invention. 1 (a) to 1 (c) and FIG. 2, the solder resist 2 runs around the component mounting land 1, so that even if a slight displacement occurs between the two, the solder resist 2 does not fall within this running amount. This has the effect that the amount of exposure of the component mounting land 1 can be absorbed and kept constant, and at the same time, the component mounting land 1 can be reinforced by the solder resist 2 running around it.

Next, a specific example of the present invention will be described. FIG.
2 (a) to 2 (c) 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. 1 (a) to 1 (c)
As shown in the figure, the component mounting land 1 is formed larger than a required predetermined mounting area, and the solder resist 2 is removed on the component mounting land 1 so as to have a predetermined mounting area. The component mounting land 1 can be exposed by an amount corresponding to the mounting area. As a result, the solder resist 2 runs over the entire periphery or a part of the component mounting land 1, so that even if a slight displacement occurs between the two, the solder resist 2 can be absorbed in the amount of running up and the component mounting land 1 can be absorbed. The exposure is always kept constant. At the same time, component mounting land 1
Can be reinforced by the solder resist 2 riding on the periphery thereof, and the peel strength between the base material 4 and the component mounting land 1 can be improved.

As shown in FIG. 2, a compressible porous base material made of an aromatic polyamide impregnated with an epoxy resin is used as a base material 4, and an aromatic polyamide as a low dielectric constant base material is used. After forming a hole and filling the conductive paste, the substrate 3 is heated and pressed to form the via 3, and then the circuit pattern 5 is repeatedly formed, so that an arbitrary interlayer can be formed without requiring a through hole. Only the electrical connection can be made, the wiring density can be increased, and at the same time, the land peeling strength, which is a conventional weak point, can be improved by running the solder resist 2 around the component mounting land 1 for the above-mentioned reason.

Further, by forming the via 3 immediately below the component mounting land 1, it is possible to electrically connect from the component mounting land 1 to another layer by a circuit pattern without being routed to another portion. It becomes possible to
At the same time, by mounting the solder resist 2 around the component mounting land 1, the land peeling strength, which has been a weak point in the related art, can be improved for the above-mentioned reason.

As described above, according to the present embodiment, if the solder resist 2 runs around the component mounting land 1, even if a slight gap occurs between the two, the solder resist 2 absorbs the difference in the running amount. Thus, the exposure amount of the component mounting land 1 is always kept constant, and at the same time, the peel 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 running around the periphery. It is possible to provide a printed wiring board capable of performing good soldering with high reliability.

In the embodiment of the present invention, the shape of the component mounting land 1 and the shape of the removed portion of the solder resist 2 are circular or square, but may be other shapes or a combination thereof.

[0022]

As described above, according to the present invention, by mounting the solder resist around the component mounting land, even if a slight deviation occurs between the two, the difference is absorbed in the running amount, and the component mounting land is absorbed. The amount of exposure is always kept constant, and at the same time, the peel strength between the base material and the component mounting land can be improved by reinforcing the component mounting land with the solder resist running around it, and high reliability of good soldering This makes it possible to realize a printed wiring board that can be performed with high flexibility.

[Brief description of the drawings]

FIGS. 1A to 1C show a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a sectional view of the printed wiring board according to the embodiment of the present invention.

FIGS. 3A and 3B show a conventional printed wiring board.

[Explanation of symbols]

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

Claims (3)

[Claims] 1. A printed wiring board wherein a solder resist is formed on a component mounting land of a circuit pattern so as to ride around or part of the component mounting land. 2. A through hole is formed in a compressible porous substrate made of an aromatic polyamide impregnated with an epoxy resin, a conductive paste is filled in the through hole, and heat is applied to both surfaces of the porous substrate. 2. The printed wiring board according to claim 1, further comprising a solder resist formed so as to ride around or part of a component mounting land of a circuit pattern formed by the metal layer pressed and bonded. 3. The printed wiring board according to claim 1, wherein a via made of a conductive paste is formed immediately below the component mounting land.