JPH0744319B2 - Printed wiring board for surface mounting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] Rectangular foot patterns are arranged at positions facing the leads of surface-mounted components mounted on a laminated board having inner layers of signal and power patterns, and the rectangular foot patterns are arranged to face each other. Two through holes each connected to the signal or power supply pattern are provided in the middle of the foot pattern, and the through hole and the outer end face edge of each foot pattern are connected by a narrow wiring pattern to achieve high density. A printed wiring board for surface mounting that facilitates mounting and modification work for circuit changes.

[Industrial application field]

The present invention relates to a printed wiring board which is widely used in the construction of various electronic devices.

Recently, the lead pitch of surface mount components (hereinafter abbreviated as SMD) is less than half that of conventional semiconductor devices, 0.8 mm to 0.8 mm.
The size is reduced to 1.27 mm, and the size of the printed wiring board is reduced to less than half accordingly, and it has a great effect to miniaturize the device, and therefore it is used in most small electronic devices.

In particular, in a printed wiring board on which SMDs are mounted at high density, wiring patterns that can deal with signal line connection changes due to circuit changes, etc. are arranged at high density, but this change connection work requires a lot of man-hours. Therefore, there is a demand for a new surface mounting printed wiring board having a pattern structure that facilitates high-density mounting and modification work for changing circuits.

[Conventional technology]

The surface mounting printed wiring board which is widely used at present is the SMD 1 shown by a broken line on the main surface of the laminated plate 2 having inner layers of wiring patterns for signals and power supplies as shown in FIG. 2 (a). A rectangular foot pattern 3 connected to the lead 1-1 of the SMD1 is arranged at a position facing the lead 1-1, and the laminated plate 2 is provided in the middle of each foot pattern 3 facing each other on the main surface, that is, at the SMD1 coating site. This is a pattern structure in which two through holes 4 each connected to an inner layer signal or power supply pattern are formed, and each through hole 4 and the inner end surface of each foot pattern 3 are connected by a narrow wiring pattern 5. .

Further, as shown in FIG. 2B, through holes 4 connected to the signal or power source pattern of the laminated plate 2 are formed on both outer sides of the facing foot pattern 3, and the wiring patterns 5 each having a narrow width are provided. Through hole 4 and each foot pattern 3
And a pattern structure in which the main surface of the laminated plate 2 is connected,
As shown in (c), through holes 4 are formed on the outer edge of each foot pattern 3 for connection with the signal or power supply pattern of the laminate 2.

As another example, as shown in FIG.
The foot patterns 3 for connecting to the leads 1-1 of the SMD1 are arranged on the main surface of each, and the foot patterns 3 facing the through holes 4 connected to the signal or power supply pattern are provided.
One through hole 4'for front and back conduction is formed near the center of each for each foot pattern 3 so as to be outside of the through hole 4, and each foot pattern 3 and each through hole is formed on the main surface side. There is also a surface mounting printed wiring board having a pattern structure in which the holes 4'are connected by a narrow wiring pattern 5 and the through holes 4 and the through holes 4'are connected by a narrow modification pattern 6 on the back surface.

[Problems to be solved by the invention]

The problems with the conventional surface-mounting printed wiring board described above are: a) In the case of the pattern shown in FIG. 2 (a), the main surface of the laminate 2 in which the through holes 4 and the wiring patterns 5 are covered by the SMD1 It is possible to reduce the component mounting area because it is installed in the, but when changing the connection of the signal line due to the circuit change after SMD mounting, melt the solder that connects the foot pattern 3 and the lead 1-1. Then, the SMD1 is removed, and then the wiring pattern 5 is cut at the pattern cut position 7 and the connection is changed with the modification wire 8. Therefore, the number of modification work steps required for changing the circuit is increased and the SMD1 is damaged due to heat shock during removal. Failure occurs in the element.

(B) Since the through hole 4 and the wiring pattern 5 are arranged outside the mounting area of the SMD1 in the structure shown in the figure (b), the pattern cut position 7 exists outside the mounting area of the SMD1 and the circuit is changed. The workability of remodeling is good, but the component mounting area per unit becomes large and high-density mounting becomes impossible.

(C) Although the component mounting area is small in the structure shown in FIG. (C), the pattern cutting position 7 is a signal or power supply pattern in the inner layer of the laminated plate 2, so that it is difficult to select the position and the remodeling work is difficult. Very difficult.

D) In another conventional example shown in FIG. 3, since the through holes 4 and 4'and the wiring pattern 5 are arranged in the mounting area of the SMD1 and the modification pattern 6 is provided on the back surface, the component mounting area is reduced. It is small and has good workability for remodeling, but when mounting components are mounted on both front and back sides, it is necessary to dispose the remodeling pattern 6 outside the mounting area of the mounted SMD, and the component mounting area per unit becomes wide. At the same time, the pattern cutting position becomes unclear, which makes the remodeling work difficult.

For example, if the component mounting area per unit is reduced, the remodeling workability for changing the circuit is deteriorated, and conversely, if the remodeling workability is improved, the component mounting area per unit is widened.

In view of the above circumstances, the present invention has an object to provide a new surface-mounting printed wiring board having a small component mounting area per unit and having a pattern structure that can be easily modified to change circuits. .

[Means for solving problems]

As shown in FIG. 1, the above problem is caused by a laminated board 2 in which a rectangular foot pattern 3 connected to the lead 1-1 of the SMD 1 shown by a broken line is provided with an unillustrated signal and power supply pattern as an inner layer.
On the principal surface of the lead 1-1,
Two through holes 4 each connected to the signal or power source pattern are arranged in the middle of each foot pattern 3 facing each other on the main surface, and the main surface side of the through hole 4 and the outer end of the foot pattern 3 are arranged. This is solved by the printed wiring board for surface mounting of the present invention in which the edges are connected by the narrow wiring pattern 15.

[Action]

That is, in the present invention, the foot pattern 3 is arranged at a position facing the lead 1-1 of the SMD 1, and the through hole 4 connected to the signal or power supply pattern is provided in each foot pattern 3
Since the through hole 4 is connected to the outer end edge of the foot pattern 3 by the wiring pattern 15,
Since the component mounting area per unit is minimized, high-density mounting is possible, and since the wiring pattern 15 from the through hole 4 is connected to the outer edge of the foot pattern 3, the pattern cut position 7 is SMD1. Outside the mounting area indicated by the broken line, when cutting or modifying the circuit, the SMD 1 is mounted and the pattern cutting and the modification wire 8 can be connected to improve the modification workability.

[Examples] The present invention will be described in detail based on the examples shown in the drawings.

FIG. 1 shows a plan view and a side sectional view of a surface-mounting printed wiring board according to this embodiment. In the figure, the same members as those in FIG. 3 are designated by the same symbols, but the other 15 are for signals. Alternatively, it is a wiring pattern in which the through hole 4 connected to the power supply pattern and the foot pattern 3 are connected to perform pattern cutting at the time of modification such as circuit change.

As shown in FIG. 1 (a), the surface mounting printed wiring board of the present embodiment has a surface mounting component, for example, a position facing the lead 1-1 of the SMD1 indicated by a broken line having a lead pitch of 1.27 mm, For example, rectangular foot patterns 3 having a width of 0.6 mm are arranged in a state of being opposed to each other on the main surface of the laminated plate 2 having inner layers of signal and power supply patterns (not shown). Then, as shown in FIG. 7B, a drill hole of, for example, 0.4 mm is formed in the middle of each of the facing foot patterns 3, and each through hole 4 connected to the signal or power source pattern by copper plating is formed. Two pieces are arranged, and the main surface side of the through hole 4 and the outer edge of the foot pattern 3 are connected by forming a wiring pattern 15 having a narrow width, for example, 0.2 mm.

With the above pattern structure, the component mounting area per unit is minimized to enable high-density mounting, and the pattern cut position 7 is outside the mounting area shown by the broken line of SMD1 as shown in FIG. When modifying, the pattern can be cut with SMD1 mounted, and the modification wire 8
Since the correction connection can be made with, the remodeling work becomes very easy.

〔The invention's effect〕

As described above, according to the present invention, there are advantages such as an extremely simple pattern structure, a small component mounting area per unit, and easy modification work for changing circuits. The effect can be expected and it is extremely useful industrially.

[Brief description of drawings]

FIG. 1 is a diagram showing a surface mounting printed wiring board according to an embodiment of the present invention, FIG. 2 is a plan view showing a conventional surface mounting printed wiring board, and FIG. 3 is a diagram showing another conventional example. In the figure, 1 is SMD, 1-1 is a lead, 2 is a laminated board, 3 is a foot pattern, 4 is a through hole, 7 is a pattern cut position, 8 is a wire, and 15 is a wiring pattern.

Claims (1)

[Claims] 1. A surface-mounting printed wiring board on which surface-mounting components are mounted, which is arranged at a position facing a lead (1-1) of the surface-mounting component (1) of a laminate (2). ,
A rectangular foot pattern (3) connected to the lead (1-1), and a signal or power supply pattern in the middle of the foot pattern (3) are connected to each of the foot patterns (3).
Surface mounting characterized by comprising a through hole (4) connected to the through hole (4) and a modification wiring pattern (15) connecting the main surface side of the through hole (4) and the foot pattern (3). Printed wiring board.