Electronic control device

1. An electronic control device comprising:

a circuit board mounting thereon electronic components; and

a connector fixed to a board edge of the circuit board and electrically connecting an electronic circuit formed on the circuit board and an external device, and

the circuit board having:

a penetration hole which a fixing member for fixing the connector to the circuit board penetrates;

a resist layer having insulating nature and covering a surface of the circuit board; and

a joining portion which is formed at a circumference of the penetration hole and to which the fixing member can be soldered, and

the resist layer having a resist layer opening which is open at the circumference of the penetration hole,

the joining portion formed at an inner side of the resist layer opening, and

the joining portion being formed so that an area of the joining portion located at an inner side of the circuit board with respect to a center of the penetration hole is larger than an area of the joining portion located at an outer side of the circuit board with respect to the center of the penetration hole.

2. The electronic control device as claimed in claim 1 , wherein:

the circuit board has an annular land at the circumference of the penetration hole,

the resist layer is formed so as to cover the land, and

the joining portion is a part, which is exposed through the resist layer opening, of the land.

3. The electronic control device as claimed in claim 1 , wherein:

a portion, which is located at the inner side of the circuit board with respect to the center of the penetration hole, of the fixing member is fixed to the joining portion by soldering.

4. The electronic control device as claimed in claim 1 , wherein:

the joining portion is formed so that a portion of the joining portion located at the inner side of the circuit board with respect to the center of the penetration hole and facing to an outer circumferential edge of the penetration hole is longer than a portion of the joining portion located at the outer side of the circuit board with respect to the center of the penetration hole and facing to the outer circumferential edge of the penetration hole.

5. The electronic control device as claimed in claim 1 , wherein:

the joining portion is formed at the inner side of the circuit board with respect to the center of the penetration hole.

6. The electronic control device as claimed in claim 1 , wherein:

the circuit board is formed into a rectangular plate shape, and has a pair of first board edges that are located on opposite sides of the circuit board and a pair of second board edges that are located on opposite sides of the circuit board, and

the joining portion is formed so that an area of the joining portion located at a middle side between the pair of first board edges with respect to the center of the penetration hole and also located at a middle side between the pair of second board edges with respect to the center of the penetration hole is larger than the other area of the joining portion.

7. The electronic control device as claimed in claim 1 , wherein:

the joining portion is formed so as to be located at an inner side of the circuit board with respect to a portion, which is positioned closest to an outer edge of the circuit board, of the outer circumference of the penetration hole.

8. The electronic control device as claimed in claim 1 , wherein:

the joining portion is formed so as to have a circular shape whose outside diameter is larger than the penetration hole and so that a center of the joining portion is offset from the center of the penetration hole toward the inner side of the circuit board.

9. The electronic control device as claimed in claim 1 , wherein:

the joining portion has a pair of first solder joining portions located at opposite sides of the penetration hole, and

each of the first solder joining portions is formed so that an area of the first solder joining portion located at the inner side of the circuit board with respect to the center of the penetration hole is larger than an area of the first solder joining portion located at the outer side of the circuit board with respect to the center of the penetration hole.

10. The electronic control device as claimed in claim 1 , wherein:

the joining portion has a pair of first solder joining portions located at opposite sides of the penetration hole and an annular solder joining portion continuously encircling an entire circumference of the penetration hole,

each of the first solder joining portions is formed so that an area of the first solder joining portion located at the inner side of the circuit board with respect to the center of the penetration hole is larger than an area of the first solder joining portion located at the outer side of the circuit board with respect to the center of the penetration hole, and

the first solder joining portions are joined to each other through the annular solder joining portion.

11. The electronic control device as claimed in claim 1 , wherein:

the joining portion has a plurality of solder joining portions arranged radially with respect to the center of the penetration hole.

12. The electronic control device as claimed in claim 1 , wherein:

the joining portion has a plurality of solder joining portions arranged radially with respect to the center of the penetration hole and an annular solder joining portion continuously encircling an entire circumference of the penetration hole, and

the solder joining portions are joined to each other through the annular solder joining portion.