JPH0737346Y2 - Land structure for screwing printed circuit boards - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a land structure for screwing a printed circuit board, and particularly to a ground and a housing of a printed circuit board for mounting an electronic component such as a microcomputer requiring a strict electromagnetic shield. The present invention relates to a land structure for screwing a printed circuit board used for screwing.

[0002]

2. Description of the Related Art In recent years, electronic parts such as a microcomputer are often used in automobile control devices, but the electronic parts are generally driven by a low voltage power supply of about 5V. However, many noise sources such as spark plugs are installed in automobiles, and in order to improve the reliability of the operation of the control device, for example, an aluminum enclosure made by die casting should be used to ensure electromagnetic shielding. There is a need.

FIG. 5 is a sectional view of a vehicle-mounted controller currently used, in which a printed circuit board 10 has electrical wirings 12a and 12b on a component mounting surface 11a and a rear surface 11b of an insulating material substrate 11, respectively. Are patterned. Then, an electronic component such as a microcomputer or a resistor is soldered to the component mounting surface 11 a and housed in the housing 13.

The back surface 11b is covered with a coating layer 14 which is an insulating material in order to protect the patterned electrical wiring 12b. There is a so-called ground, which serves as a reference potential, in the electrical wiring, but in order to prevent the ground potential from being disturbed by external noise, the ground on the printed circuit board 10 and the housing 11 should be electrically connected. However, conventionally, there are many cases in which the ground on the printed board 10 and the housing 13 are connected by a conductor cable.

However, in the case of connecting with a conductor cable, naturally, a conductor cable wiring process is required, and an increase in man-hours or production cost cannot be avoided. In order to solve this problem, it is common that the printed circuit board 10 is screwed to the housing 13,
The applicant has already proposed a “land structure for screwing a printed circuit board”, which secures electrical connection between the printed circuit board 10 and the housing 13 with a screw (Japanese Patent Application No. 4-3099).
5).

[0006]

However, the above-mentioned proposal is such that the screw holes on the back surface 11 of the printed circuit board 10 are
By patterning the ground land and removing the solder resist material or coating layer applied on the ground land at the screw head by the screw rotating force when fixing the screw, the electrical connection between the screw and the ground land is eliminated. Since the contact is secured, there is a possibility that the solder resist material or the coating layer may not be electrically contacted when it is crushed.

It is clear that it is necessary to more surely secure the electrical contact with a control device such as a fuel injection control device or an antilock brake control device which is required to have high reliability. The present invention has been made in view of the above problems, and an object of the present invention is to provide a land for screwing a printed circuit board, in which electrical connection between the ground of the printed circuit board and the housing is further ensured by screwing. .

[0008]

A land structure for screwing a printed circuit board according to a first aspect of the present invention shields a printed circuit board and a component mounting surface on which electrical wiring is patterned on a component mounting surface and a back surface of an insulating substrate. A land structure for screwing the printed circuit board, which electrically connects the ground land of the electric circuit formed on the printed circuit board by a mounting screw used to integrate the case and the case, , Star-shaped screwing lands having a plurality of radial protrusions around the screw holes into which the mounting screws are inserted are provided on the component mounting surface and back surface of the insulating substrate, and on the component mounting surface and back surface of the insulating substrate. It is characterized in that the provided screwing lands are electrically connected by at least one via hole.

In the land structure for screwing the printed circuit board according to the second invention, a through hole having a large hole diameter is provided in place of the via hole and sucked up by a capillary phenomenon during soldering on the back surface of the printed circuit board. The solder thus formed is formed as a solder layer on a screwing land on the component mounting surface of the printed circuit board.

[0010]

According to the printed circuit board screwing land structure of the first invention, even when the insulator is sandwiched between the head of the mounting screw and the screwing land on the rear surface of the printed circuit board, the print is performed. Direct contact between the screwing lands provided on the board component mounting surface and the housing ensures electrical connection between the printed circuit board ground and the housing.

In the printed circuit board screw land structure according to the second aspect of the present invention, the through-hole sucks up the solder during soldering on the back surface of the printed circuit board and the solder layer is formed on the screw land on the component mounting surface. When formed, the electrical connection between the printed circuit board ground and the housing is made more reliable.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan view of an embodiment of a land structure for screwing a printed circuit board according to the first invention.
Shows the component mounting surface of the printed circuit board, and (b) shows the back surface of the printed circuit board. FIG. 2 is a sectional view of the printed circuit board taken along line XX. That is, the screw mounting lands 15a and 15b on the component mounting surface 11a and the back surface 11b of the printed circuit board 10, respectively.
Is concentrically patterned around the screw hole 17 into which the mounting screw 16 is inserted. And component mounting surface 1
The screw fastening lands 15a and 15b on the back surface 11a and the back surface 11b are electrically connected by four via holes 181 to 184.

Solder resist 19 is applied to the parts mounting surface 11a and the back surface 11b of the printed circuit board 10 where solder does not need to be attached. In the first embodiment, the parts mounting surface 11a and the back surface 11b are screwed. In the lands 15a and 15b, the solder resist 19 is formed so that the conductive portion has a radial shape having four protrusions.
Is applied.

In FIG. 1, the cross-hatched area represents the area where the solder resist 19 is applied. When the back surface 11b of the printed circuit board 10 is soldered, the solder layer 20 is formed on the screwing lands 15b on the back surface 11b. Attach the mounting screw 16 to the screw hole 17
When the printed circuit board 10 and the housing 13 are integrated with each other, the heads of the mounting screws 16 come into contact with the radial lands 15b on the back surface 11b through the solder layer 20, and the printed circuit board ground and the housing 13 are connected. And are electrically connected. Since the solder layer 20 is made of a material having elasticity, the solder layer 20 can maintain the tightening force without using a spring washer.

Further, the mounting screw lands 15a provided on the component mounting surface 11a directly contact the housing 13 to electrically connect the ground of the printed circuit board and the housing 13. In the first embodiment, the radial projections are formed by applying the solder resist to the concentric circular lands, but the lands themselves may be patterned to have the radial projections.

3 and 4 are a plan view and an X-X sectional view of the second embodiment. In the second embodiment, the through holes 21 are replaced with the through holes 21.
1-214 are provided. The same reference numerals as those in FIGS. 1 and 2 represent the same elements. With the through holes 211 to 214, when soldering the back surface 11b, the molten solder is sucked into the through holes 211 to 214 by the capillary phenomenon and spreads in the shape of the land 15a on the component mounting surface 11a.

That is, not only the solder layer 20b is formed on the back surface 11b, but also the solder layer 20a is formed on the component mounting surface 11a. Therefore, when the mounting screw 16 is tightened, the housing 13 is integrated so as to bite into the solder layer 20a, and the electrical connection between the ground of the printed circuit board 10 and the housing 13 can be further ensured. .

The land can be formed in the same manner as in the first embodiment.

[0019]

According to the first aspect of the invention, the screw land structure not only electrically connects the screw land provided on the back surface of the printed circuit board to the housing by the mounting screw, but also the back surface. Electrically connected to the screw land and via holes The screw land provided on the printed circuit board component mounting surface directly contacts the housing to ensure electrical connection between the printed circuit board ground and the housing. It becomes possible to do.

According to the screw fastening land structure of the second invention, since the solder is sucked up to the component mounting surface by the through hole and the solder layer is formed also on the screw fastening land on the component mounting surface, the print is performed. It is possible to further ensure the electrical connection between the ground of the board and the housing.

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment.

FIG. 1 is a sectional view taken along line XX of the first embodiment.

FIG. 3 is a plan view of the second embodiment.

FIG. 4 is a sectional view taken along line XX of the second embodiment.

FIG. 5 is a cross-sectional view of a vehicle-mounted control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Insulating substrate 13 ... Housing 14 ... Protective coating layer 15 ... Screw land 16 ... Mounting screw 181-184 ... Via hole 19 ... Solder resist

Claims (2)

[Scope of utility model registration request] 1. A printed circuit board on which an electrical wiring is patterned on a component mounting surface and a back surface of an insulating substrate and a mounting screw used for integrating a casing for shielding the component mounting surface on the printed circuit board. A land structure for screwing a printed circuit board for electrically connecting a ground land of an electric circuit formed in the above and the housing, wherein a plurality of radial projections are provided around a screw hole into which the mounting screw is inserted. The star-shaped screw fastening lands are provided on the component mounting surface and the back surface of the insulating substrate, and the screw fastening lands provided on the component mounting surface and the back surface of the insulating substrate are at least one via. A land structure for screwing a printed circuit board, which is electrically connected by holes. 2. A through hole having a large hole diameter is provided instead of the via hole, and the solder sucked up by a capillary phenomenon during soldering on the back surface of the printed circuit board is a component mounting surface of the printed circuit board. A screw land structure for a printed circuit board, which is formed as a solder layer on the screw land.