JP2001332851A - Method for manufacturing printed wiring board and land part thereof, and method for mounting the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a land part of a printed wiring board which can suppress and prevent the generation of a liftoff phenomenon and a land release phenomenon even when lead-free solder is used to mount a component. SOLUTION: The outer peripheral part of the land 14 provided on the top surface of a printed wiring board so as to mount the component by using the lead-free solder is covered with an extension part 21 of a solder mask 20 formed on the top surface of the printed wiring board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a land portion of a printed wiring board, a method for manufacturing a printed wiring board, and a method for mounting a printed wiring board, and more particularly to a method for using lead-free solder (lead-free solder). The present invention relates to a method for manufacturing a land portion of a printed wiring board and a printed wiring board, and a method for mounting a printed wiring board using lead-free solder.

[0002]

2. Description of the Related Art Conventionally, the outermost surface of a printed wiring board is covered with a solder mask except for a land portion and a connector portion. The arrangement relationship between the land portion and the solder mask is schematically shown in a partial plan view of FIG. 6A and a partial end view of FIG. 6B. The printed wiring board is formed, for example, by using a printed board 10 made of a glass epoxy copper-clad laminate in which copper foils 11 are stacked on both sides, forming a through-hole 13 in the printed board 10 by through-hole plating and through-hole plating. , Plating layer 12 and copper foil 11
The wiring (not shown) and the land portions 14 (14A, 14B) are formed by the etching process described above, and the solder mask 20 is formed. In FIG. 6A, in order to clearly show the land portion 14 and the solder mask 20, these are hatched from upper left to lower right and from upper right to lower left.

Usually, as shown in FIG. 6, the outer peripheral portion of the land portion 14 is not covered with the solder mask 20 formed on the surface of the printed wiring board. A clearance CL exists between the outer edge 114 of the land 14 and the end of the solder mask 20. This clearance CL is, for example, 6.4.5 of JIS C 5013 (1990).
According to Chapter, the minimum clearance is 2 for Class I
00 μm, 100 μm for class II, and 50 μm for class III.

Conventionally, a solder used for soldering a printed wiring board is a eutectic solder of tin-lead (Sn-Pb). Lead in the solder has a role of lowering the melting point, promoting fluidity, and lowering the surface tension. However, regarding the toxicity of lead, its effect on the human body has been a problem for some time. Also, environmental pollution by lead has become a problem. Therefore, in recent years, development and use of lead-free solder (lead-free solder) have been promoted. The components of the lead-free solder are, for example, 93 to 98% by weight of tin, and the rest is composed of silver, copper, and antimony, and there are also those in which bismuth, cadmium, nickel, sulfur, arsenic, and zinc are mixed in trace amounts. . The melting temperature of lead-free solder is 21
0 to 230 ° C., which is higher than the melting temperature of the tin-lead eutectic solder (about 183 ° C.).

When soldering a lead portion 40 of a component as a component mounting portion to the through hole portion 13 shown in FIG.
The lead portion 40 is inserted into the through-hole portion 13 from the component mounting surface side, and the tip portion of the lead portion 40 exposed on the soldering surface side opposite to the component mounting surface is used to form a fillet 31 using solder. To the land portion 14B on the soldering surface side. The solder penetrates and fills a gap between the through-hole 13 and the lead 40, and the solder that has passed through the through-hole 13 forms a fillet on the land 14A on the component mounting surface side. by this,
The portion of the lead portion 40 on the component mounting surface side is soldered to the land portion 14A.

[0006]

When such a lead-free solder having a high melting temperature is used for component mounting, as shown in a schematic partial end view of FIG.
A lift-off (solder peeling) phenomenon occurs in which the fillet 31 is peeled off from the land part 14, and a land peeling phenomenon occurs in which the land part 14 peels off from the surface of the base material 10A constituting the printed circuit board 10. It is to be noted that a state in which a lift-off (solder peeling) phenomenon has occurred is schematically shown on the left side of the land part in FIG. 7, and a state in which the land peeling phenomenon has occurred is schematically shown on the right side of the land part in FIG. In some cases, lead-free solder 3 from the surface of the lead portion 40 of the component may be used.
Also, a phenomenon such as the peeling of 0 and the phenomenon that the plating layer 12A (see FIG. 6B) formed on the inner wall of the through-hole portion 13 peels from the inner wall of the base material 10A also occur. In particular, the occurrence of the land peeling phenomenon and the peeling of the plating layer 12A are fatal defects for the printed wiring board after component mounting.

The lift-off phenomenon and the land peeling phenomenon do not occur so much when a conventional leaded solder is used, but are frequent when a lead-free solder is used. Regardless of the soldering method, that is, for example, the flow soldering method or the iron soldering method occurs in the same manner. Also, there is no correlation with the soldering method at the site where these phenomena occur. These phenomena may also occur when components are removed from the lands using a soldering iron. It is presumed that these phenomena occur due to thermal shrinkage and solidification shrinkage of the lead-free solder, but at present, appropriate means for suppressing or preventing the occurrence of these phenomena have not been established.

Accordingly, an object of the present invention is to provide a printed wiring which can suppress and prevent the occurrence of a lift-off phenomenon and a land peeling phenomenon even when a lead-free solder having a high melting temperature (lead-free solder) is used for component mounting. It is an object of the present invention to provide a land portion of a board, a method for manufacturing a printed wiring board, and a method for mounting a printed wiring board.

[0009]

According to a first aspect of the present invention, there is provided a printed wiring board having a land portion provided with a lead-free solder for mounting components using lead-free solder. A land portion provided on the surface, wherein an outer peripheral portion of the land portion is covered with an extension of a solder mask formed on a surface of the printed wiring board.

In the land portion of the printed wiring board according to the first aspect of the present invention, the outer peripheral portion of the land portion is covered with an extended portion of the solder mask at least 5 × 10 ⁻⁵ m from the outer edge of the land portion. In consideration of variations in the land portion and solder mask formation process, the occurrence of land peeling phenomena, especially the occurrence of land peeling phenomena due to manual attachment and detachment of parts using a soldering iron, etc., is ensured. It is desirable from the viewpoint of suppressing and preventing. The area of the land portion that is not covered by the extending portion of the solder mask is arbitrary as long as component mounting can be reliably performed, and is determined in consideration of the size and shape of the component to be mounted on the land portion. I just need. The same applies to the method for manufacturing a printed wiring board according to the first embodiment of the present invention described below or the method for mounting a printed wiring board according to the present invention.

[0011] In order to achieve the above object, the second aspect of the present invention.
The land portion of the printed wiring board according to the aspect extends the component mounting surface and the soldering surface of the printed wiring board from a through-hole portion provided in the printed wiring board for mounting components using lead-free solder. And at least an outer peripheral portion of the land portion extending on the component mounting surface is covered with an extension portion of a solder mask formed on the component mounting surface of the printed wiring board.

In the land portion of the printed wiring board according to the second aspect of the present invention, the outer peripheral portion of the land portion extending on the component mounting surface is at least 5 × 10 ⁻⁵ m from the outer edge of the land portion, The fact that it is covered by the solder mask extension formed on the component mounting surface of the printed wiring board ensures that the occurrence of the lift-off phenomenon and the land peeling phenomenon will occur in consideration of variations in the land and solder mask formation processes. It is desirable from the viewpoint of suppression and prevention. The area of the land portion that is not covered by the extending portion of the solder mask is arbitrary as long as component mounting can be reliably performed, and is determined in consideration of the size and shape of the component to be mounted on the land portion. I just need. In some cases, substantially all of the lands extending on the component mounting surface may be covered with the extensions of the solder mask. That is, substantially only the through-hole portion may be exposed. The same applies to the method for manufacturing a printed wiring board according to the second embodiment of the present invention described below or the method for mounting a printed wiring board according to the present invention.

In the land portion of the printed wiring board according to the second aspect of the present invention, the outer periphery of the land portion extending on the soldering surface is formed by a solder mask formed on the soldering surface of the printed wiring board. Although it is not necessary to cover, it is preferable to cover with the extending portion of the solder mask formed on the soldering surface of the printed wiring board from the viewpoint of suppressing and preventing the occurrence of the lift-off phenomenon and the land peeling phenomenon. In the latter case, the outer peripheral portion of the land extending the component mounting surface is 5 × 10 from the outer edge of the land.
^-5 m or more, covered by the extension of the solder mask formed on the component mounting surface of the printed wiring board, and the outer periphery of the land extending on the soldering surface is 5 × 10 ⁻ from the outer edge of the land. ⁵ m or more is covered by the extension of the solder mask formed on the soldering surface of the printed wiring board. It is more desirable from the viewpoint of more surely suppressing and preventing the occurrence. The area of the portion where the land portion extending on the component mounting surface is not covered by the extension portion of the solder mask is the area of the portion where the land portion extending on the soldering surface is not covered by the extension portion of the solder mask. It is desirable that the width be smaller than that. As a result, the component can be more securely mounted (fixed) on the land portion.

The first object of the present invention for achieving the above object is as follows.
In the method for manufacturing a printed wiring board according to the aspect, (A) a step of forming wiring and a land on the surface of the printed board; and (B) a step of forming a solder mask on the surface of the printed board to obtain the printed wiring board In the step (B), the outer peripheral portion of the land portion is covered with an extended portion of the solder mask formed on the surface of the printed circuit board.

The first object of the present invention for achieving the above object is as follows.
The printed wiring board mounting method according to the aspect (A) includes: a step of forming a wiring and a land on the surface of the printed board;
(B) a process of forming a solder mask on the surface of a printed circuit board to obtain a printed wiring board; and (C) fixing a component mounting portion to a land portion using lead-free solder, and mounting the component on the printed wiring board. (B)
Wherein the outer peripheral portion of the land portion is covered with an extended portion of the solder mask formed on the surface of the printed circuit board.

In the method for manufacturing a printed wiring board or the method for mounting a printed wiring board according to the first aspect of the present invention, in the step (B), the outer peripheral portion of the land portion is placed 5 × from the outer edge of the land portion. It is desirable to cover with an extension of the solder mask of 10 ^-5 m or more.

The second object of the present invention to achieve the above object.
The method for manufacturing a printed wiring board according to the aspect (A), comprises: (A) forming a through hole, a land portion and a wiring extending from the through hole to a component mounting surface and a soldering surface of the printed circuit board. And (B) a step of forming a solder mask on the component mounting surface and the soldering surface of the printed circuit board to obtain a printed wiring board. In the step (B), a land extending at least on the component mounting surface is provided. An outer peripheral portion of the portion is covered with an extending portion of a solder mask formed on a component mounting surface of the printed circuit board.

The second object of the present invention for achieving the above object is as follows.
In the printed wiring board mounting method according to the aspect, (A) a through-hole portion, and a land portion and a wiring extending from the through-hole portion to the component mounting surface and the soldering surface of the printed circuit board are formed. And (B) a step of forming a solder mask on a component mounting surface and a soldering surface of a printed circuit board to obtain a printed wiring board; and (C) inserting a component mounting portion into a through-hole portion and using lead-free solder. Fixing the component mounting portion to the through-hole portion and the land portion, thereby mounting the component on the printed wiring board;
In the step (B), at least an outer peripheral portion of the land portion extending on the component mounting surface is covered with an extended portion of the solder mask formed on the component mounting surface of the printed circuit board.

In the method for manufacturing a printed wiring board or the method for mounting a printed wiring board according to the second aspect of the present invention, in the step (B), the outer peripheral portion of the land portion extending on the component mounting surface is removed. It is desirable to cover at least 5 × 10 ⁻⁵ m from the outer edge of the land with the extending portion of the solder mask formed on the component mounting surface of the printed wiring board.

Alternatively, in the method for manufacturing a printed wiring board or the method for mounting a printed wiring board according to the second aspect of the present invention, in the step (B), the outer periphery of the land portion extending on the soldering surface may be used. It is not necessary to cover the portion with the solder mask formed on the soldering surface of the printed wiring board, but covering with the extension of the solder mask formed on the soldering surface of the printed wiring board may cause a lift-off phenomenon and land peeling. It is desirable from the viewpoint of suppressing and preventing the occurrence of the phenomenon. In the latter case, the step (B)
In, the outer peripheral portion of the land portion extending the component mounting surface,
At least 5 × 10 ⁻⁵ m from the outer edge of the land portion is covered with an extended portion of a solder mask formed on the component mounting surface of the printed wiring board, and the outer peripheral portion of the land portion extending on the soldering surface is covered with the land portion. Covering with a solder mask extending portion formed on the soldering surface of the printed wiring board by 5 × 10 ⁻⁵ m or more from the outer edge is not suitable for the lift-off phenomenon and the variation in the land portion and the solder mask forming process. It is more desirable from the viewpoint of more reliably suppressing and preventing the occurrence of the land peeling phenomenon. Also, the area of the portion where the land extending the component mounting surface is not covered by the extension of the solder mask is the area of the portion where the land extending the soldering surface is not covered by the extension of the solder mask. It is desirable to make it smaller than the area. As a result, the component can be more securely mounted (fixed) on the land portion.

In the land portion of the printed wiring board, the method of manufacturing the printed wiring board, or the method of mounting the printed wiring board (hereinafter, these may be collectively simply referred to as the present invention) in the present invention. The size and the diameter of the through hole are essentially arbitrary, and may be determined based on the specifications required for the printed wiring board, the dimensions of the components to be mounted, and the like. In addition, the planar shape of the land portion is also essentially arbitrary, and may be a circle, an ellipse, a rectangle including a square or a rectangle,
It can be a rounded rectangle, a polygon, or a rounded polygon. When the land shape is circular,
It is preferable that the shape of the outer edge of the land portion and the shape of the edge portion of the extending portion of the solder mask covering the land portion are substantially similar. That is, even if there is a variation depending on the accuracy of forming the solder mask, the distance from the outer edge of the land to the edge of the extending portion of the solder mask covering the land depends on the position of the outer edge of the land. Regardless, it is desirable that they are substantially equal. When the planar shape of the land portion is a shape other than a circle, the shape of the edge of the extending portion of the solder mask covering the land portion is preferably circular. That is, even if there is a variation depending on the accuracy of forming the solder mask, the distance from the outer edge of the land to the edge of the extending portion of the solder mask covering the land depends on the position of the outer edge of the land. Regardless of the minimum value, for example, 5
It is desirable to keep × 10 ⁻⁵ m. In many cases, one or a plurality of wires extend from the land portion, but the width, thickness, and the like of the wires may be determined based on specifications required for the printed wiring board.

In the present invention, the composition and characteristics of the lead-free solder (lead-free solder) to be used are essentially arbitrary. For example, the component is 93 to 98% by weight of tin (Sn), Is composed of silver (Ag), copper (Cu), and antimony (Sb), and includes bismuth (Bi), cadmium (Cd), nickel (Ni), sulfur (S), and arsenic (A).
s), zinc (Zn), cobalt (Co), phosphorus (P),
It is possible to use those in which a small amount of indium (In) is mixed. For example, Sn-Bi, Sn-Bi-Ag-C
u, Sn-Zn, Sn-Zn-In, Sn-Ag-Z
n, Sn-Ag, Sn-Ag-Cu, Sn-Ag-Bi
—Cu, Sn—Cu can be exemplified. Note that, depending on the component to be mounted, the mounting method, and the soldering method, a lead-free cream solder (solder paste) having the above components may be used.

As the solder mask (also referred to as solder resist) in the present invention, a thermosetting resin film, an ultraviolet curable resin film, a photosensitive resin film, a so-called dry film can be used. When the solder mask is formed of a thermosetting resin film, a heat treatment may be performed after printing the thermosetting resin on the surface (the component mounting surface, the soldering surface) of the printed circuit board by a screen printing method. When the solder mask is made of a UV-curable resin film, the UV-curable resin may be printed on the surface of the printed circuit board (component mounting surface, soldering surface) by a screen printing method, and then subjected to UV irradiation. Further heat treatment may be performed as desired. When the solder mask is composed of a photosensitive resin film, a photosensitive resin phase is formed on the surface of the printed circuit board (component mounting surface, soldering surface) by screen printing, spraying, curtain coating, spin coating, etc. After that, exposure, development and curing may be performed. When the solder mask is composed of a dry film, the dry film may be laminated on the surface of the printed circuit board (component mounting surface, soldering surface), and then subjected to exposure, development, and curing. Alternatively, an adhesive layer may be formed on a film. In this case, a hole is formed in the film corresponding to the land by drilling, punching, laser processing, or the like, and such a film is laminated on the surface of the printed circuit board (component mounting surface, soldering surface). Thereafter, a curing process may be performed.

As the printed wiring board of the present invention, a rigid printed wiring board having wiring formed on one or both sides, a multilayer rigid printed wiring board, a multilayer flex rigid printed wiring board, a metal core printed wiring having wiring formed on one or both sides Examples include a board, a multilayer metal core printed wiring board, a metal base printed wiring board having wiring formed on one or both sides, a multilayer metal base printed wiring board, a build-up multilayer printed wiring board, and a ceramic wiring board. The manufacturing method of these various printed wiring boards may be a conventional method, and the formation of the land portion, the wiring, and the through-hole portion is a so-called subtractive method including a panel plating method and a pattern plating method, An additive system such as a semi-additive system and a full additive system may be used. The configuration of the substrate constituting the printed board is essentially arbitrary, for example, paper / phenol resin, paper / epoxy resin,
Glass cloth / epoxy resin, glass nonwoven / epoxy resin, glass cloth / glass nonwoven / epoxy resin, synthetic fiber / epoxy resin, glass cloth / polyimide resin, glass cloth / modified polyimide resin, glass cloth / epoxy modified polyimide resin, glass cloth / Bismaleimide / Triazine / Epoxy resin, Glass cloth / Fluorine resin, Glass cloth / PP
O (polyphenylene oxide) resin, glass cloth / PP
A combination of E (polyphenylene ether) resins can be exemplified. The wiring (circuit) and the land are formed, for example, by etching a copper foil (or copper-plated copper foil). The thickness of the copper foil is determined based on the specifications required for the wiring and the land. 70μ
m thickness, 35 μm thickness, 18 μm thickness, 12 μm thickness, and 9 μm thickness can be exemplified. The thickness of the plating layer may be determined based on the specifications required for the printed wiring board.

Various square or cylindrical resistive chips, SO packages, etc. are used as parts in the land portion of the printed wiring board, the method for manufacturing the printed wiring board, or the method for mounting the printed wiring board according to the first aspect of the present invention. Resistor networks, various capacitor chips, various inductor chips, various mechanical parts (for example, chip-type semi-fixed volume, chip-type light touch switch), special function parts (for example, chip-type varistor, chip-type surface acoustic wave filter, chip-type) Chip components such as ceramic oscillators and chip-type EMI filters, LCC (Leadless Chip Carr)
ier), PLCC (Plastic Leaded Chip Carrier), S
OP (Small Outline Package), QFP (Quad Flat P)
An IC component represented by an ackage can be exemplified.
These components are referred to as surface mounting components for convenience.

Further, as parts in the land portion of the printed wiring board, the method for manufacturing the printed wiring board, or the method for mounting the printed wiring board according to the second aspect of the present invention, carbon film resistors, cylindrical ceramic capacitors, diodes, etc. Axial lead parts, ceramic capacitors, aluminum electrolytic capacitors, radial lead parts such as transistors, SIP (Single Inline Package) and DIP (Dual
IC components represented by Inline Package) and PGA (Pin Grid Array), and various connectors. These components are referred to as components with leads for convenience.

In the method for manufacturing a printed wiring board, a method for manufacturing a printed wiring board, or a method for mounting a printed wiring board according to the first or second embodiment of the present invention, components are mounted using lead-free solder. Specific methods include iron soldering; various dip soldering methods;
Wave type, double wave type, flow dip type, single flow type, electromagnetic type, inert atmosphere type, plasma type,
Various flow soldering methods such as ultrasonic jet type; infrared heating type, hot air heating type, saturated steam heating type, hot plate heating type,
Various reflow soldering methods such as a laser heating method, a liquid heating method, and an inert atmosphere method can be used.

In mounting components on a printed wiring board,
Cases where surface mount components are mounted on one side of a printed wiring board, cases where surface mount components are mounted on both sides of a printed wiring board, cases where components with leads are mounted on one side of a printed wiring board, one side of a printed wiring board There are various cases, such as a case where a component for mounting a surface and a component with a lead portion are mounted on a printed wiring board, a case where a component for mounting a surface is mounted on both sides of a printed wiring board, and a component with a lead portion is mounted on one side. And in each of these cases, the first of the present invention
The land portion of the printed wiring board, the method for manufacturing the printed wiring board, or the method for mounting the printed wiring board according to the second aspect or the second aspect may be properly used, and the first printed wiring board according to the first aspect of the present invention may be used for one printed wiring board. There may be many cases where the land portions of the printed wiring boards according to the first and second aspects are mixed, and the printed wiring according to the first and second aspects of the present invention is applied to one printed wiring board. It is often possible to simultaneously apply a board manufacturing method or a printed wiring board mounting method.

In the land portion of the printed wiring board, the method of manufacturing the printed wiring board, or the method of mounting the printed wiring board according to the first aspect of the present invention, the land is formed by the extension of the solder mask formed on the surface of the printed wiring board. Since the outer peripheral portion of the portion is covered, the occurrence of the land peeling phenomenon can be reliably suppressed and prevented. Further, in the land portion of the printed wiring board, the method of manufacturing the printed wiring board, or the method of mounting the printed wiring board according to the second aspect of the present invention, the extending portion of the solder mask formed on the component mounting surface of the printed wiring board. Since the outer periphery of the land that extends the component mounting surface is covered, the volume of the fillet can be reduced.As a result, the stress during solder solidification can be reduced, and the occurrence of lift-off and land peeling phenomena can be reliably suppressed. In addition, if the outer peripheral portion of the land portion extending on the soldering surface is covered with the extending portion of the solder mask formed on the soldering surface of the printed wiring board, the lift-off phenomenon and the land peeling phenomenon can be prevented. Can be more reliably suppressed and prevented.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

Example 1 Example 1 relates to a land portion of a printed wiring board, a method of manufacturing the printed wiring board, and a method of mounting the printed wiring board according to the first embodiment of the present invention. The positional relationship between the land and the solder mask is schematically shown in a partial plan view of FIG. 1A and a partial end view of FIG. 1B. The printed wiring board of the first embodiment uses, for example, a printed board 10 made of a glass epoxy copper-clad laminate (thickness: 1.0 mm) in which a copper foil (thickness: 18 μm) 11 is laminated on one side, and a copper foil 11 It is manufactured through well-known processes such as formation of wiring (not shown) and land portion 14 by etching, and formation of solder mask 20 made of an ultraviolet curable resin film. The wiring extends from the land. In FIG. 1A, a hatched line from the upper right to the lower left is attached to clearly show the solder mask 20. The reference numeral 114 indicates the land portion 14.
The outer edge of is shown.

The lands 14 are provided on the surface of the printed wiring board for mounting components using lead-free solder. In Example 1, the planar shape of the land portion 14 was a rectangle of 0.9 mm × 1.4 mm. The outer peripheral portion of the land portion 14 is covered with the extending portion 21 of the solder mask 20 formed on the surface of the printed wiring board. Here, the outer peripheral portion of the land portion 14 is at least 5 × 10 ⁻⁵ m from the outer edge 114 of the land portion 14, and in the first embodiment, an average of 75 μm (= L).
0 is covered by the extending portion 21. That is, in the first embodiment, the solder mask 2 covering the land portion 14 is used.
0 is 0.75 mm × 1.2
It was a 5 mm rectangle.

In Example 1, Sn—Ag—Cu,
And a surface mount component having a Sn-10Pb plating layer formed thereon by a hot-air heating type reflow soldering method using a lead-free cream solder (solder paste) containing Sn-Ag-Bi-Cu as a main component. Was fixed to the land portion 14, and the component was mounted on the printed wiring board. Thereafter, the parts were detached and attached using a blower or a soldering iron, and the occurrence of a land peeling phenomenon was examined.

As Comparative Example 1, an average distance between the outer edge 114 of the land 14 and the end of the solder mask 20 was 75 μm.
A printed wiring board was manufactured in the same manner as in Example 1 except that the clearance CL was provided, and fixtures were mounted on the lands in the same manner as in Example 1.

It was examined whether a lift-off phenomenon and a land peeling phenomenon occurred on the land portion of the printed wiring board after the component was mounted. Specifically, it was examined whether or not the wiring extending from the land portion was disconnected due to the occurrence of these phenomena.
A failure was determined when disconnection occurred in any one place on one printed wiring board. In Example 1, there was no printed wiring board in which disconnection occurred. On the other hand, in Comparative Example 1, the printed wiring board in which the disconnection occurred occupied about 10%, though it depends on the skill of the worker. From these results, by employing the land portion of the printed wiring board, the method for manufacturing the printed wiring board, and the method for mounting the printed wiring board according to the first aspect of the present invention, the occurrence of the lift-off phenomenon and the land peeling phenomenon can be dramatically reduced. It was found that it could be prevented.

Example 2 Example 2 relates to a land portion of a printed wiring board, a method of manufacturing the printed wiring board, and a method of mounting the printed wiring board according to the second embodiment of the present invention. The arrangement relationship between the land portion and the solder mask is schematically shown in a partial plan view of FIG. 2A and a partial end view of FIG. 2B. The printed wiring board of Example 2 is, for example, a glass cloth / epoxy resin copper-clad laminate (FR-4, having a thickness of 1.times.) Having copper foils (thickness: 18 μm) 11 laminated on both sides.
6 mm), a through-hole (diameter: 0.8 mm) 13 is formed by through-hole plating, and wiring is formed by etching the plating layer 12 and the copper foil 11. It is manufactured through well-known processes such as formation of land portions 14 (14A, 14B) and formation of solder mask 20. In FIG. 2A, to clearly show the land portion 14 and the solder mask 20, these are hatched from upper left to lower right and from upper right to lower left. Reference numeral 114 indicates an outer edge of the land portion 14.

The land portions 14 (14A, 14B)
A component mounting surface and a soldering surface of the printed wiring board extend from a through-hole portion 13 provided on the printed wiring board for mounting components using lead-free solder. In the second embodiment, the outer peripheral portion of the land portion 14A extending on the component mounting surface is covered with the extending portion 21 of the solder mask 20 formed on the component mounting surface of the printed wiring board, and has a soldering surface. Is also covered by the extending portion 21 of the solder mask 20 formed on the soldering surface of the printed wiring board.

In the second embodiment, the lands 14A, 1
The plane shape of 4B was a circle having a diameter of 1.35 mm. Here, the outer peripheral portions of the land portions 14A and 14B are
5 × 10 ⁻⁵ m or more from outer edges 114 of A and 14B, 50 μm (= L) on average in Example 2, extension of solder mask 20 formed on component mounting surface and soldering surface of printed wiring board Covered by the part 21. That is, in the second embodiment, the shape of the edge of the extending portion 21 of the solder mask 20 that covers the lands 14A and 14B is
It was circular with a diameter of 1.25 mm.

In Example 2, Sn-3.0Ag-
Using a lead-free solder containing 0.5Cu and Sn-0.7Cu as main components, using a soldering iron, a component mounting portion of a component with a lead portion in which a Sn-10Pb plating layer is formed on a brass surface. The (lead portion 40) is inserted into the through-hole portion 13 from the component mounting surface side of the land portion 14 and the component mounting portion (lead portion 40) is inserted into the through-hole portion 13 and the land portions 14A and 14B using lead-free solder. After fixing, the components were mounted on a printed wiring board. This state is schematically shown in FIG.

As a comparative example 2, the lands 14A, 1
4B except that an average clearance CL of 75 μm is provided between the outer edge 114 of 4B and the end of the solder mask 20;
The planar shape of the lands 14A and 14B is 1.35 mm in diameter.
, And the shape of the end of the solder mask 20 has a diameter of 1.
A printed wiring board was manufactured in the same manner as in Example 2 except that the printed wiring board was formed in a circular shape of 5 mm.

The same evaluation as in Example 1 was performed. Example 2
In, there was no printed wiring board in which disconnection occurred. On the other hand, in Comparative Example 2, the printed wiring board in which the disconnection occurred accounted for about 17.5%. From these results, by employing the land portion of the printed wiring board, the method for manufacturing the printed wiring board and the method for mounting the printed wiring board according to the second aspect of the present invention, the occurrence of the lift-off phenomenon and the land peeling phenomenon can be dramatically reduced. It was found that it could be prevented.

(Embodiment 3) Embodiment 3 is a modification of Embodiment 2. In the third embodiment, the land portions 14A, 14B
Was a square with a side of 1.35 mm. Also,
The shape of the edge of the extension 21 of the solder mask 20 covering the lands 14A and 14B was a circle having a diameter of 1.25 mm. Then, components were mounted on the lands in the same manner as in Example 2. Incidentally, as Comparative Example 3, the land portions 14A, 1
4B except that an average clearance CL of 75 μm is provided between the outer edge 114 of 4B and the end of the solder mask 20;
A printed wiring board was manufactured in the same manner as in Example 3 except that the shape of the end of the solder mask 20 was a square having a side of 1.5 mm, and fixtures were mounted on the lands in the same manner as in Example 3. As a result, in Example 3, there was no printed wiring board in which disconnection occurred. On the other hand, in Comparative Example 3, the printed wiring board in which disconnection occurred accounted for about 20%.

(Fourth Embodiment) The fourth embodiment is also a modification of the second embodiment. In the fourth embodiment, as shown in a schematic partial end view of FIG.
Is the area of a portion not covered by the extending portion 21 of the solder mask 20 with the land portion 1 extending on the soldering surface.
4B is smaller than the area of the portion not covered by the extending portion 21 of the solder mask 20.

More specifically, in the fourth embodiment, the planar shape of the lands 14A and 14B is a circle having a diameter of 1.35 mm. And a land portion 14A extending on the component mounting surface.
The shape of the edge of the extending portion 21 of the solder mask 20 that covers the soldering surface is a circle having a diameter of 1.1 mm, and the extending portion 2 of the solder mask 20 that covers the land portion 14B that extends the soldering surface.
The shape of the edge portion 1 was a circle having a diameter of 1.25 mm. Then, components were mounted on the lands in the same manner as in Example 2. As a result, in Example 4, there was no printed wiring board in which disconnection occurred.

The planar shape of the lands 14A and 14B is a square of 1.35 mm on a side. Then, the solder mask 2 covering the land portion 14A extending on the component mounting surface
0 has a circular shape with a diameter of 1.1 mm, and the shape of the edge of the extending portion 21 of the solder mask 20 covering the land portion 14B extending on the soldering surface has a diameter of 1.
The shape was a 25 mm circle. Then, components were mounted on the lands in the same manner as in Example 2. As a result, there was no printed wiring board in which disconnection occurred.

(Embodiment 5) Embodiment 5 is also a modification of Embodiment 2.
It is. In the fifth embodiment, the land portions 14A, 14B
Was a circular shape having a diameter of 1.5 to 2.25 mm.
Here, the outer peripheral portions of the land portions 14A and 14B are the land portions.
5 × 10 from outer edge 114 of 14A, 14B ^-Fivem or more, real
In Example 2, the printed wiring board was 75 μm on average.
Solder mass formed on component mounting surface and soldering surface
The coating 20 is covered by the extending part 21 of the metal. That is,
In the fifth embodiment, the lands 14A and 14B are covered.
The shape of the edge of the extending portion 21 of the solder mask 20 is defined as a diameter.
It was a circle of 1.35 to 2.1 mm.

In Example 5, Sn-2.5% Ag
Using a lead-free solder containing -1% Bi-0.5% Cu as a component, by a double wave type flow soldering method,
The component mounting portion (lead portion) of the component with the lead portion on which the Sn-10Pb plating layer is formed is inserted into the through-hole portion 13 from the component mounting surface side of the land portion 14 and the component mounting portion (lead-free solder) is used. Lead) through hole 13
Then, the components were fixed to the lands 14A and 14B, and the components were mounted on the printed wiring board.

As a comparative example 5, the land portions 14A, 1
4B except that an average clearance CL of 75 μm is provided between the outer edge 114 of 4B and the end of the solder mask 20;
The land portions 14A and 14B have a planar shape with a diameter of 1.5-2.
A printed wiring board was manufactured in the same manner as in Example 5, except that the shape of the end portion of the solder mask 20 was a circle having a diameter of 1.65 to 2.4 mm. Fixtures were mounted on the land.

It was examined whether a lift-off phenomenon and a land peeling phenomenon occurred on the land portion of the printed wiring board after the component was mounted. In addition, when a lift-off phenomenon and a land peeling phenomenon occurred even in one place on one printed wiring board, it was determined to be defective. The results are shown in Tables 1 and 2 below. The number of printed wiring boards evaluated was 100 each.

[0050]

[0051]

Although the present invention has been described based on the preferred embodiments, the present invention is not limited to these embodiments. The configuration and manufacturing conditions of the printed wiring board, the component mounting method and conditions, the used lead-free solder, the lead-free cream solder, and the components used in the embodiments are merely examples, and can be appropriately changed. FIG. 5A is a partial plan view schematically showing the positional relationship between the land portion and the solder mask;
As shown in the partial end view of FIG. 5B, almost all of the land portion 14A extending on the component mounting surface is formed of the solder mask 20.
May be covered by the extending portion 21. Further, even when the conventional leaded solder is used, the land portion may peel off from the surface of the base material when the use condition of the component mounting printed wiring board is severe. In such a case, it is preferable to apply the land portion of the printed wiring board, the method for manufacturing a printed wiring board, or the method for mounting a printed wiring board, even if a conventional leaded solder is used.

[0053]

According to the present invention, the occurrence of the land peeling phenomenon and the lift-off phenomenon can be suppressed and prevented. As a result, there is no disconnection of the wiring caused by these phenomena.
The reliability of the printed wiring board or the component mounted printed wiring board can be remarkably improved.

[Brief description of the drawings]

FIGS. 1A and 1B are a partial plan view and a partial end view schematically showing a positional relationship between a land portion and a solder mask in a printed wiring board of Example 1. FIGS.

FIGS. 2A and 2B are a partial plan view and a partial end view schematically showing a positional relationship between a land portion and a solder mask in the printed wiring board of Example 2. FIGS.

FIG. 3 is a partial end view schematically showing a state in which components are mounted on lands in Example 2.

FIG. 4 is a partial plan view and a partial end view schematically showing the positional relationship between a land portion and a solder mask in the printed wiring board of Example 4.

FIG. 5 is a view showing a modification of the printed wiring board according to the second embodiment;
It is the partial top view and partial end view which show typically the arrangement relationship of a land part and a solder mask.

6A and 6B are a partial plan view and a partial end view schematically showing a positional relationship between a land portion and a solder mask in a conventional printed wiring board.

FIG. 7 is a schematic partial end view of a printed wiring board for explaining a problem when lead-free solder is used in a conventional printed wiring board.

[Explanation of symbols]

10 ... printed circuit board, 10A ... base material, 11 ...
・ Copper foil, 12, 12A: plating layer, 13: through hole, 14, 14A, 14B: land, 1
14: outer edge of land, 20: solder mask,
21 ... extended part of solder mask, 30 ... lead-free solder, 31 ... fillet, 40 ... lead part of part, CL ... clearance

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masao Karaba 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Yoshihiko Miyake 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Hideyuki Arakane 7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 5E314 AA27 BB06 BB09 BB10 FF05 FF19 GG12 GG24 5E319 AA02 AC02 BB05 BB08 CC23 CC33 CC53 GG15

Claims (21)

[Claims] 1. A land portion provided on a surface of a printed wiring board for mounting a component using lead-free solder, and an outer peripheral portion of the land portion is a solder mask formed on a surface of the printed wiring board. A land portion of the printed wiring board, wherein the land portion is covered by an extending portion. 2. The printed wiring board according to claim 1, wherein an outer peripheral portion of the land portion is covered with an extended portion of the solder mask at least 5 × 10 ⁻⁵ m from an outer edge of the land portion. Land section. 3. A through-hole provided on a printed wiring board for mounting components using lead-free solder.
A land portion extending on the component mounting surface and the soldering surface of the printed wiring board, at least an outer peripheral portion of the land portion extending on the component mounting surface is
A land portion of the printed wiring board, wherein the land portion is covered with an extension of a solder mask formed on a component mounting surface of the printed wiring board. 4. An outer peripheral portion of the land portion extending on the component mounting surface is covered with an extended portion of the solder mask formed on the component mounting surface of the printed wiring board at least 5 × 10 ^-5 m from an outer edge of the land portion. The land portion of the printed wiring board according to claim 3, wherein the land portion is formed. 5. The method according to claim 3, wherein an outer peripheral portion of the land portion extending on the soldering surface is covered with an extending portion of the solder mask formed on the soldering surface of the printed wiring board. Land of printed wiring board. 6. An outer peripheral portion of a land portion extending on a component mounting surface is covered with an extending portion of a solder mask formed on a component mounting surface of a printed wiring board at least 5 × 10 ⁻⁵ m from an outer edge of the land portion. The outer periphery of the land extending on the soldering surface is covered with an extension of a solder mask formed on the soldering surface of the printed wiring board at least 5 × 10 ⁻⁵ m from the outer edge of the land. The land portion of the printed wiring board according to claim 5, wherein: 7. The area of a portion where a land extending on a component mounting surface is not covered by an extension of a solder mask is:
The land portion of a printed wiring board according to claim 3, wherein the land portion extending on the soldering surface is smaller than the area of the portion not covered by the extension portion of the solder mask. 8. A process for forming a wiring and a land on a surface of a printed circuit board, and (B) a step for forming a solder mask on a surface of the printed circuit board to obtain a printed circuit board. In (B), a method of manufacturing a printed wiring board, wherein an outer peripheral portion of a land portion is covered with an extended portion of a solder mask formed on a surface of a printed circuit board. 9. The method according to claim 8, wherein in the step (B), the outer peripheral portion of the land portion is covered with an extended portion of the solder mask at least 5 × 10 ⁻⁵ m from the outer edge of the land portion. Manufacturing method of printed wiring board. 10. A step of forming a through-hole portion on a printed circuit board, and a land portion and a wiring extending from the through-hole portion to a component mounting surface and a soldering surface of the printed circuit board; and Forming a solder mask on the component mounting surface and the soldering surface of the printed circuit board to obtain a printed wiring board. In the step (B), at least the outer peripheral portion of the land portion extending on the component mounting surface is printed. A method for manufacturing a printed wiring board, characterized in that the printed wiring board is covered with an extension of a solder mask formed on a component mounting surface of a substrate. 11. In the step (B), the outer peripheral portion of the land portion extending on the component mounting surface is placed 5 × from the outer edge of the land portion.
The method for manufacturing a printed wiring board according to claim 10, wherein the printed wiring board is covered with an extended portion of a solder mask formed on a component mounting surface of the printed wiring board by 10 ⁻⁵ m or more. 12. In the step (B), an outer peripheral portion of a land portion extending on the soldering surface is covered with an extending portion of a solder mask formed on the soldering surface of the printed wiring board. A method for manufacturing a printed wiring board according to claim 10. 13. In the step (B), the outer peripheral portion of the land portion extending on the component mounting surface is placed 5 × from the outer edge of the land portion.
The outer peripheral portion of the land portion extending over the soldering surface is covered with an extending portion of the solder mask formed on the component mounting surface of the printed wiring board at least 10 ^-5 m, and the outer peripheral portion of the land portion is 5 × 10 ^-5 from the outer edge of the land portion. 13. The method for manufacturing a printed wiring board according to claim 12, wherein the coating is performed by an extension of a solder mask formed on a soldering surface of the printed wiring board for at least m. 14. A land portion extending on the component mounting surface covers an area of a portion not covered by the extension portion of the solder mask, and a land portion extending on the soldering surface is covered by the extension portion of the solder mask. The method for manufacturing a printed wiring board according to claim 10, wherein the area is smaller than the area of the part without the part. 15. A step of forming a wiring and a land on the surface of a printed board; (B) a step of forming a solder mask on the surface of the printed board to obtain a printed wiring board; Fixing the component mounting portion to the land using solder, and thus mounting the component on the printed wiring board;
A method of mounting a printed wiring board, wherein in the step (B), an outer peripheral portion of a land portion is covered with an extending portion of a solder mask formed on a surface of a printed circuit board. 16. The method according to claim 15, wherein in the step (B), the outer peripheral portion of the land portion is covered with an extension of the solder mask at least 5 × 10 ⁻⁵ m from the outer edge of the land portion. Printed wiring board mounting method. 17. A step of: (A) forming a through-hole on a printed circuit board; and a land and wiring extending from the through-hole to a component mounting surface and a soldering surface of the printed circuit board; and (B) Forming a solder mask on the component mounting surface and the soldering surface of the printed circuit board to obtain a printed wiring board; and (C) inserting the component mounting portion into the through-hole portion and using a lead-free solder to form the component mounting portion with the through-hole. And mounting the component on the printed wiring board. In the step (B), at least the outer peripheral portion of the land extending on the component mounting surface is fixed to the printed circuit board. A method for manufacturing a printed wiring board, characterized in that the printed wiring board is covered with an extension of a solder mask formed on a component mounting surface. 18. In the step (B), the outer peripheral portion of the land portion extending on the component mounting surface is placed 5 × from the outer edge of the land portion.
18. The printed wiring board mounting method according to claim 17, wherein the printed wiring board is covered with an extended portion of a solder mask formed on a component mounting surface of the printed wiring board at least 10 ^-5 m. 19. The method according to claim 18, wherein in the step (B), an outer peripheral portion of the land portion extending on the soldering surface is covered with an extending portion of a solder mask formed on the soldering surface of the printed wiring board. The printed wiring board mounting method according to claim 17. 20. In the step (B), the outer peripheral portion of the land portion extending on the component mounting surface is placed 5 × from the outer edge of the land portion.
The outer peripheral portion of the land portion extending over the soldering surface is covered with an extending portion of the solder mask formed on the component mounting surface of the printed wiring board at least 10 ^-5 m, and the outer peripheral portion of the land portion is 5 × 10 ^-5 from the outer edge of the land portion. 20. The printed wiring board mounting method according to claim 19, wherein the coating is performed with an extension of a solder mask formed on a soldering surface of the printed wiring board for at least m. 21. The area of a portion where the land portion extending on the component mounting surface is not covered by the extension portion of the solder mask, and the land portion extending on the soldering surface is not covered by the extension portion of the solder mask. 18. The method according to claim 17, wherein the area is smaller than the area of the portion.