JPH05267833A - Surface mounting printed wiring board - Google Patents

Abstract

PURPOSE:To fix a surface mounting electronic component to a printed wiring board securely and realize the reliable solder joint between the surface mount electronic component and a land by a method wherein solder lumps created at the time of a solder leveller treatment are eliminated. CONSTITUTION:A third land 24 is provided between a first land 22 which correspond to a surface mounting electronic component and a second land 24a which is provided near the first land 22 and connected to it and has a through-hole 24b. At the time of solder leveller treatment, solder 26 passing through the through-hole 24b flows toward a first air nozzle 28a side in a second air nozzle 28b passing stage when a printed wiring board is lifted up. Before the solder 26 is accumulated on the first land 22 through the second land 24a and a conductor pattern 23, the excessive solder is made to adhere to the third land 24 to avoid the creation of solder lumps.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mounting printed wiring board which is used in many electronic devices such as an engine controller of an automobile and a mobile phone.

[0002]

2. Description of the Related Art In recent years, printed wiring boards have been required to be compact, lightweight, multifunctional, and highly reliable in electronic equipment, and to have automatic surface mounting of electronic components. Has been done. Further, demands for heat resistance such as assurance of solderability against multiple heating in the mounting process such as double-sided mounting of electronic components for surface mounting are becoming severe.

For this reason, a conventional rosin-based resin coating method has been adopted for the treatment of the copper surface forming the conductor patterns and lands of a printed wiring board, but a synthetic resin-based one is used for the purpose of improving heat resistance. Examples are increasing. However, in terms of guaranteeing solderability in long-term storage of printed wiring boards and flow soldering after multiple times of reflow soldering, a method of solder coating exposed conductor patterns, through holes and lands of printed wiring boards (hereinafter, Solder leveler treatment) is excellent, and it is often used especially in printed wiring boards for surface mounting.

A conventional surface mount printed wiring board will be described below. 8 to 17 show shapes of lands corresponding to surface-mounting electronic components of conventional surface-mounting printed wiring boards and lands having through holes connected thereto, solder leveler processing methods, and printed-wiring boards for surface-mounting electronic components. It shows the mounting state in. 1 in the figure
Is a printed wiring board, 1a is an insulating substrate, 2 is a first land for surface mounting, 3 is a conductor pattern, 4a is a second land having a through hole, 4b is a through hole, 5 is a solder resist, and 6 is solder. , 7 is a solder leveler device, 8
a is the first air nozzle, 8b is the second air nozzle,
8c is hot air, 9 is coated solder,
Reference numeral 10 is a solder pool, 11 is an electronic component for surface mounting, and 12 is an adhesive for fixing the electronic component for surface mounting.

The operation of the surface mounting printed wiring board, the solder leveler processing method, and the mounting of the surface mounting electronic component configured as described above will be described below.

First, NC is applied to a double-sided copper-clad laminate (not shown).
A drilling machine is used to form holes for forming through holes, and copper plating is used to form through holes that electrically connect both surfaces. After forming this through hole, an etching resist is formed by using a screen method, a photo-developing method or the like, and etching is performed using a solution of cupric chloride or the like.
And the first land 2 for surface mounting as shown in FIG.
The second land 4a having the conductor pattern 3 and the through hole 4b is formed.

Next, the conductor pattern 3 which does not require soldering
And a solder resist 5 is formed on the insulating substrate 1a, and
A printed wiring board 1 as shown in (1) is obtained, and then a solder leveler process is performed.

Next, as shown in FIGS. 11 (a) to 11 (c),
The printed wiring board 1 set on a chucking jig (not shown) of the solder leveler device 7 descends and is dipped in the molten solder 6 for a predetermined time, and when it is pulled up, the printed wiring board 1 descends and rises. The hot air 8c ejected from the air nozzles 8a and 8b arranged on both sides scrapes off the solder 6 adhering to the printed wiring board 1 to make the adhering solder amount and thickness uniform.

Next, an outer shape and a hole are formed in a predetermined shape by a die or the like, and as shown in FIG.
Is in a completed state, and is transferred to an electronic component mounting process after undergoing an inspection process for defects such as the conductor pattern 3 and appearance.

On the printed wiring board 1 conveyed in the electronic component mounting step, the surface mounting electronic components 11 are fixed at one or a plurality of locations near the center between the first lands 2 for surface mounting or in the vicinity of the center. The adhesive 12 for application is applied using a means such as a dispenser, and after mounting the surface mount electronic component 11, it is heated and fixed as shown in FIG.

[0011]

However, in the conventional surface-mounting printed wiring board 1 described above, the surface-mounting printed wiring board 1 is connected to the first land 2 corresponding to the surface-mounting electronic component 11 as shown in FIGS. When the second land 4a having the adjacent through holes 4b is provided, the first and second two pairs of air nozzles 8a and 8b in the solder leveler device 7 are provided in the through hole 4b during the solder leveler process. Since the solder is installed so as to maintain a certain step as shown in FIG. 11 so as not to be stagnant, the first air nozzle 8 is passed through the second air nozzle 8b at the time of pulling up.
The solder 6 which has passed through the through hole 4b to the side a passes through the land 4a having the through hole 4b and the conductor pattern 3, and as shown in FIGS.
A phenomenon (hereinafter referred to as a solder pool 10) of accumulating on the upper side occurs.

As a result, in the electronic component mounting process, the adhesive 12 for fixing the surface mounting electronic component 11 is applied to one or a plurality of points in the center or near the center between the first lands 2 for surface mounting. When the surface mounting electronic component 11 is mounted, heated and fixed, the surface mounting electronic component 11 does not reach the adhesive 12, as shown in FIG.
Moreover, even if it arrives, a sufficient adhesive force cannot be obtained, and the surface mounting electronic component 11 falls into the solder bath during the flow soldering, or as shown in FIG. 17, the leads of the surface mounting electronic component and the surface mounting electronic component are mounted. There was a risk of damaging the reliability of electronic equipment such as a solder joint failure on the land.

The present invention solves the above-mentioned problems of the prior art by preventing the solder from accumulating on the surface mounting lands during the solder leveler treatment, ensuring the secure attachment of the surface mounting electronic components and the printed wiring board, and the surface mounting electronic. An object of the present invention is to provide a surface-mounting printed wiring board that realizes reliable solder bonding between a component and a surface-mounting land.

[0014]

In order to achieve this object, the surface mounting printed wiring board of the present invention corresponds to a surface mounting electronic component formed on an insulating substrate in a solder coated printed wiring board. A first land and a second land having an adjacent through hole,
In addition, a third land connected to the first land is provided between the first land and the second land.

[0015]

[Operation] With this configuration, during the solder leveler treatment,
At the stage of passing through the second air nozzle at the time of pulling up, the first
It becomes possible to attach excess solder to the third land before the solder that has passed through the through hole to the air nozzle side passes through the second land and the conductor pattern and collects on the first land for surface mounting. It is possible to prevent generation of solder pool on the surface mounting land.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 show shapes of a land corresponding to an electronic component for surface mounting of a printed wiring board for surface mounting and a land having a through hole connected to the land in a first embodiment of the present invention. (C) and FIG.
FIG. 7 shows a solder leveler processing method and a mounting state of a surface mounting electronic component on a printed wiring board.

In the figure, 21 is a printed wiring board, and 21a.
Is an insulating substrate, 22 is a first land for surface mounting, 23 is a conductor pattern, 24 is a third land, 24a is a second land having a through hole, 24b is a through hole, 2
5 is a solder resist, 26 is solder, 27 is a solder leveler device, 28a is a first air nozzle, 28b is a second air nozzle.
Air nozzle, 28c hot air, 29 coated solder, 31 surface mounting electronic component, 32
Is an adhesive for fixing electronic components for surface mounting.

1 to 7 showing the surface mounting printed wiring board, the solder leveler treatment, and the mounting state of the surface mounting electronic components configured as described above on the printed wiring board.
The operation will be described using.

First, a land corresponding to a surface mounting electronic component, a hole such as a conductor pattern or a through hole, etc. is drawn from an electronic circuit diagram, necessary information such as a component position and outer dimensions for a printed wiring board. At the same time, as shown in FIGS. 1 to 3, the third land 24 is inserted through the diameter of the through hole 24b of the second land 24a, the area of the second land 24, and the insulating substrate 1a corresponding to the second land 24a. After considering the land diameter on the opposite side and the area of the conductor pattern 23 connected to the land and setting the area appropriately, the first surface mounting
Pattern between the land 22 and the second land 24a having the through hole 24b or the through hole 24
It is provided so as to be connected near the land 24a having b,
Draw. From these, various tools necessary for manufacturing a printed wiring board such as a master film for manufacturing are manufactured, and the printed wiring board is manufactured by a conventional manufacturing method.

First, a copper clad laminate (not shown) in which copper foil is laminated on both sides of an insulating substrate is cut into a predetermined size, and then a hole is formed using an NC drilling machine or the like, and the whole surface including the hole wall surface is cut. A conductor layer is formed by plating. Next, an etching resist is formed in a predetermined pattern using a photo-developing method or the like, the exposed conductor layer is etched with a solution of cupric chloride, etc., and the insulating resist 2 is peeled off.
A conductor pattern 23 and a through hole 24b are formed on the la 1a, and then a solder resist 25, a road map, etc. are formed by a photo-developing method, a screen printing method or the like to obtain a printed wiring board 21 as shown in FIG.

Next, as shown in FIG. 5, the printed wiring board 21 is attached to the chuck portion (not shown) of the solder leveler device 27.
, And the printed wiring board 21 that was set descends,
It is dipped in the molten solder 26 in the solder bath for a predetermined time and then pulled up. At the time of this pulling up, the molten solder 26 adhering to the conductor exposed surface such as the conductor pattern 23 of the printed wiring board 21 is blown off by the hot air ejected from the first air nozzles 28a and 28b and is blown to the conductor surface to a predetermined extent. The amount and thickness adhere.

At this time, as shown in FIG. 6, in the through hole 24b connected to and adjacent to the first land 24 corresponding to the surface mounting electronic component, two pairs of opposing air in the solder leveler device 27 are connected. Nozzles 28a and 28
b is the solder 26 in a molten state such as in the through hole 24b
Since it is installed so as to maintain a certain level difference so as not to stagnate, the molten solder 26 that has passed through the through hole 24b toward the first air nozzle 28a side during the second air nozzle 28b passing at the time of pulling up The second land 24a and the conductor pattern 23 are used to accumulate in the first land 22 for surface mounting, but the through hole 24b connected to the first land 22 corresponding to the electronic component for surface mounting and adjacent to the through hole 24b is formed. It is absorbed by the third land 24 provided between the second land 24a and the first land 22 that it has, and prevents a solder pool from being generated in the first land 22.

After that, the outer shape and mounting holes are processed,
The printed wiring board 21 having a predetermined shape is completed.

Next, in the electronic component mounting step, the printed wiring board 21 is bonded at one or a plurality of locations near the center between the first lands 22 for surface mounting to fix the electronic components for surface mounting. Agent 32 is applied,
After the surface mounting electronic component 31 is mounted, heated and fixed,
Flow soldered.

As shown in FIG. 7, since no solder pool is generated on the first land, the surface mounting electronic component 31 can reliably reach the adhesive 32 and a sufficient adhesive force can be obtained.

In the surface-mounted printed wiring board according to this embodiment, no drop of the surface-mounting electronic component 31 into the solder bath was observed during flow soldering, and the electrodes of the surface-mounting electronic component 31 and the surface-mounting were not mounted. An excellent effect can be obtained in terms of reliable solder joining of the land 22.

In the embodiment, the printed wiring board 21 is used.
Is a double-sided printed wiring board, but the printed wiring board 21 may be a single-sided printed wiring board, a multilayer printed wiring board, or the like.

Although the soldering method is flow soldering, it goes without saying that the soldering method may be reflow soldering using cream solder.

[0029]

As described above, according to the present invention, the first land corresponding to the electronic component for surface mounting formed on the insulating substrate is connected to the second land having the through hole and the first land. By providing a third land between the lands, the solder for the surface mounting land is prevented during the solder leveler processing, and the surface mounting electronic component and the printed wiring board are securely fixed and the surface mounting electronic component and the surface mounting are mounted. It is possible to realize an excellent surface-mounting printed wiring board which can be solder-bonded to the land for reliability.

[Brief description of drawings]

FIG. 1 is a plan view showing a land of a surface mounting printed wiring board according to an embodiment of the present invention.

FIG. 2 is a plan view showing lands of a surface mounting printed wiring board according to an embodiment of the present invention.

FIG. 3 is a plan view showing lands of a surface mounting printed wiring board according to an embodiment of the present invention.

FIG. 4 is a sectional view of a printed wiring board for surface mounting.

5A to 5C are conceptual diagrams for explaining an operation of a solder leveler processing method for a surface mounting printed wiring board according to an embodiment of the present invention.

FIG. 6 is a sectional view for explaining the operation of the solder leveler processing method for a surface mounting printed wiring board according to an embodiment of the present invention.

FIG. 7 is a sectional view showing a mounting state of the surface mounting component.

FIG. 8 is a plan view showing a land of a conventional surface mounting printed wiring board.

FIG. 9 is a plan view showing a land of a conventional surface mounting printed wiring board.

FIG. 10 is a sectional view of a printed wiring board for surface mounting.

11A to 11C are conceptual diagrams for explaining an operation of a solder leveler processing method for a surface mounting printed wiring board.

FIG. 12 is a sectional view of the same surface mounting printed wiring board.

FIG. 13 is a cross-sectional view for explaining the operation of the method for mounting the surface mounting component on the surface mounting printed wiring board.

FIG. 14 is a sectional view of the same.

FIG. 15 is a plan view of the same.

FIG. 16 is a sectional view of the same.

FIG. 17 is a sectional view of the same.

[Explanation of symbols]

 21 printed wiring board 21a insulating substrate 22 first land 23 conductor pattern 24 third land 24a second land 24b through hole

Claims (1)

[Claims] 1. A printed wiring board to be solder coated has a first land corresponding to a surface mounting electronic component formed on an insulating substrate and a second land having a through hole adjacent thereto, and a first land. And a third land connected to the first land is provided between the land and the second land.