JPH02122694A - Double-sided printed circuit board for sop type smd - Google Patents

Abstract

PURPOSE:To improve the density of signal wiring and to improve the degree of freedom of the position of through-hole by overlapping the footprint on the front and rear faces. CONSTITUTION:In a SOP type SMD2 having a power supply terminal 5 and a ground terminal 7 at diagonal positions, the position of footprints overlap on the front and rear faces. Consequently, the area for making through-holes 4 while avoiding the footprint 3 increases when compared with the case where the footprints do not overlap, thus increasing the freedom of arrangement. Furthermore, each SOP type SMD 2 is mounted such that the row 6 of the power supply terminals 5 overlaps on the front side and the rear side. Consequently, respective through-holes 4 for connecting the power supply terminals 5 and the ground terminals 7 at the end of the row with the power source wiring and ground wiring can be used commonly by adjoining front and rear faces of a row of SOP type SMD2 through shortest wiring.

Description

[Detailed Description of the Invention] [Summary] The purpose of the present invention is to provide a printed board with double-sided mounting of SOP-type SMDs that improves signal wiring density and increases the degree of freedom in through-hole positioning. In order to mount SOP type SMDs on both the front and back sides of a printed board, the footprints of the SOP type SMDs are provided at positions where they overlap on the front and back sides, and through holes are placed at corresponding predetermined positions on both sides near the rows of footprints. SOP type SMD with the terminal rows including the power supply terminals overlapped on the front and back surfaces.
Configure to implement.

[Industrial application field]

The present invention relates to a printed board on which sop type SMDs are mounted on both sides.

Electronic components used in electronic devices, including semiconductor components, are becoming smaller and more sophisticated, and mounting on printed circuit boards has changed from conventional insert-type components that require insertion of terminal leads. Surface mount type components (hereinafter referred to as SMD) that eliminate leads and have external surfaces as terminal surfaces are becoming mainstream.

The printed circuit board that makes up the circuit uses multilayer wiring that uses through holes to connect between the eyebrows and thinner wiring to support high-density mounting, while with the advent of SMD, a double-sided mounting method that mounts components on both the front and back has become practical. It has come to be.

[Conventional technology]

FIG. 2 shows an implementation diagram of a conventional example of double-sided mounting.

As an example of the conventional example, two identical SOP type SMDs each having terminals arranged in two rows of five terminals have four power supply terminals 5 and ground terminals 7 located at the same diagonal position, two each on the front and back surfaces. The state of close mounting will be described as shown in FIG.

In the figure, the state of the front side is shown by a solid line, and the state of the back side seen through from the front side is shown by a dotted line.

That is, it is difficult to provide the through hole 4 at the location of the footprint 3 for connection of the SOP type SMD 2, and therefore the through hole 4 must be provided at a location outside the footprint 3.

In addition, the printed board 15 with multilayer wiring can be used to shield wiring between the front side and the back side, and to arrange connecting parts and through holes for components on the front and back sides without restrictions. Power supply wiring and ground wiring are provided in the intermediate layer, and connections to the SoP type SMD 2 are made by providing through holes 4 near each power supply terminal 5 and ground terminal 7 to connect to the intermediate layer.

Furthermore, through holes 4 are provided at necessary locations for connection of other circuits and are used for connection between wiring layers.

[Problem to be solved by the invention]

However, (1) the general through-hole 4 must be provided in a position that avoids both or one of the footprint 3 of the surface-mounted SMD 2 and the footprint 3 of the back-mounted SMD 2, and is subject to restrictions.

■ At least two through holes 4 are required for each SMD 2 for power supply connection and ground connection.

■ Alternatively, providing a leader line randomly from the footprint 3 and aiming for the common use of the through hole 4 is recommended for SMD
This may affect the signal circuit between Z and impede the high density of signal circuit wiring.

There are other problems.

In view of these problems, the present invention has been developed to improve signal wiring density and increase the degree of freedom in through hole positioning.
The purpose is to provide double-sided mounting of MD.

[Means to solve the problem]

The above problem is as shown in FIG. 1, when the SOP type SMD 2 is mounted on both the front and back sides of the printed board l, the footprint 3 of the SOP type SMD 2 is provided at a position where the front and back sides overlap, and the through hole 4 is are provided at corresponding predetermined positions on both sides near the column of footprint 3,
In addition, the sop type SMD 2 of the present invention is mounted in a direction in which the terminal row 6 including the power supply terminal 5 overlaps on the front and back surfaces.
This problem is solved by a double-sided mounting printed board of type SMD.

[For production]

That is, since the footprint positions of the SMD are overlapped on the front and back surfaces, the degree of freedom of the through hole is increased, and the power supply terminals are in the same terminal row, making it possible to share the through hole, so that the purpose can be met.

In the SOP type SMD 2, which has the same shape and has the power supply terminal 5 and the ground terminal 7 at diagonal positions, the positions of the fund blinds 3 in surface mounting and back surface mounting overlap, so they are placed in non-overlapping positions as in the conventional example described above. Footprint 3 compared to the case where
The area in which the through hole 4, which must be provided while avoiding the problem, can be provided increases, and the degree of freedom in arrangement increases.

Furthermore, since each sop type SMD 2 is mounted in a direction in which the terminal row 6 of the power supply terminal 5 overlaps on the front side and the back side,
Through holes 4 connecting the power supply terminals 5 and ground terminals 7 at the end of the row to the power wiring and ground wiring provided in the intermediate layer are connected to the adjacent front and back surfaces of the SAP type SMDs 2 arranged in the - row. Can be used commonly with the shortest wiring.

By reducing the number of through holes 4 through common use, signal wiring density can be improved.

In this way, it is possible to provide double-sided mounting of the sop type SMD, which improves the signal wiring density and increases the degree of freedom in the position of through holes.

〔Example〕

The gist of the present invention will be specifically explained below with reference to embodiments shown in the drawings. The same reference numerals indicate the same objects throughout the figures, and FIG. 1 shows an embodiment of the present invention.

- An example in which two SOP type SMDs 2 arranged adjacent to each other in a row are mounted on both sides will be described with reference to FIG.

In Figure 1, the state of the front side is shown with a solid line, and the state of the back side seen through from the front side is shown with a dotted line, but overlaps of the same size are double-written with the solid line inside and the dotted line outside. be.

A footprint 3 is provided at each terminal position of the SOP type SMD 2 in which five terminals are arranged in duplicate, and the footprints 3 are positioned so that they overlap on the front and back sides, and the terminal row 6 including the power supply terminal 5 is also
They overlap on the front and back.

The positions for providing through holes 4 are determined corresponding to each of the footprints 3, and the corresponding predetermined positions on both sides of the terminal row 6 and other terminal rows 61 near the footprint 3 row, In the embodiment, the upper and lower positions and the end portions are provided at the left and right positions in the figure, and the lower position is used on the front side, and the upper position is used on the back side.

The through hole 4 is not a conventionally large one that requires a lead wire to pass through or soldering. If you use a small through-hole connector with a connection between the eyebrows by plating, you can create a sop type SM with narrow terminal spacing.
It can be fully applied to D2 as well.

〔Effect of the invention〕

As described above, according to the present invention, since the footprints are overlapped on the front and back sides, the area for creating through holes is greatly increased, the degree of freedom is increased, and there are no unconnectable signal wirings, and the wiring rate is improved. By aligning the mounting directions on the front and back sides, the through holes for connection with the power supply wiring and ground wiring in the intermediate layer can be shared on the adjacent front and back sides, so that the power supply terminal 5 and the ground terminal 7 at the end can be connected to each other. The number of through holes corresponding to this can be reduced, the area for creating signal wiring increases accordingly, and the signal wiring density can be improved, which has great effects.

[Brief explanation of drawings]

FIG. 1 is an implementation diagram of an embodiment of the present invention, and FIG. 2 is an implementation diagram of a conventional example of double-sided mounting. In the figure, 1.15 is a printed board, and 2 is a sop type SMD. 3 is a footprint, 4 is a through hole, 5 is a power supply terminal, 6 and 61 are terminal rows, and 7 is a ground terminal. A and the flesh side of the first A row to the east 'F, t's actual decay opening 2n

Claims (1)

[Claims] In order to mount the SOP type SMD (2) on both the front and back sides of the printed board (1), the footprints (3) of the SOP type SMD (2) are provided at positions where they overlap on the front and back sides, and the through holes (4) are provided. The SOP type S is provided at corresponding predetermined positions on both sides near the row of footprints (3), and the terminal rows (6) including the power supply terminals (5) overlap on the front and back sides.
SOP type S characterized by implementing MD (2)
MD double-sided mounting printed board.