JPH11274766A - Circuit board fixing structure of electronic control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a structure which prevents material fatigue of a solder bonding part between a connection terminal and a circuit board which is to be generated by vibration during running of a vehicle, and prevents stress concentration from being developed in the solder bonding part which is to be caused by thermal strain. SOLUTION: In a control unit 1, a hydraulic unit 2 containing a plurality of control valves 5 which are electronically controlled and a hydraulic pump 4, and an electronic control unit 3 containing connecting terminals 8 of an electric connector 7, and a circuit board 10 are combined. The circuit board 10 is fixed with a resin housing 11 of the electronic control unit 3 by using individually arranged fixing members. The connection terminals 8 molded on the electric connector 7 side forming a part of the resin housing 11 are perpendicularly stretched and soldered to through holes of the circuit board 10. The length of the fixing member and the distance from a mold positioning part of the connection terminal 8 to the aperture of the through hole are equalized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for fixing a circuit board on which various control elements are mounted in an on-vehicle electronic control unit constituting a hydraulic control system such as an anti-lock brake system for an automobile.

[0002]

2. Description of the Related Art A control unit of a hydraulic control system used for an anti-lock brake system of an automobile includes a hydraulic unit including a hydraulic pump and a plurality of control valves, a connector of a power supply for driving the hydraulic unit, and a hydraulic unit. And a circuit board on which various control elements for driving the control valve of the pressure unit are mounted.

[0003] The housing of the electronic control unit has a housing molded of resin, and an electromagnetic coil and connection terminals that are molded in advance are mounted on a printed circuit board to which various control elements are coupled. And electrically connected through a soldering operation. Further, the circuit board is mechanically fixed to the resin housing side in order to absorb vibration during the running of the automobile.

[0004] Japanese Patent Application Laid-Open No. 8-121323 has proposed an example of the configuration. FIG. 7 is a sectional view of the electronic control unit 100. Reference numeral 101 denotes a resin housing, which is formed integrally with the electrical connector 102 having a plurality of pins. The electromagnetic coil 103 is mounted on a coil mounting seat 104 having a plug-in locking portion 105,
Reference numeral 6 denotes a coil printed circuit board 107 provided with a U-shaped curved portion in the middle to alleviate the stress on the solder joint.
Soldered.

The coil printed circuit board 107 is formed by bending a sill pin 108 extending upward from the resin housing 101 and sandwiching the sealing member 109 therebetween.
01 is mechanically fixed. The control circuit board 111 on which the various control elements 110 are mounted is the electrical connector 1
02 is electrically connected by soldering to a connection terminal 112 extending from
The tip of the pin 113 fixed to the control circuit board 1
By soldering the control circuit board 11, the control circuit board 111 is mechanically supported. Finally, the lower cover 114 is assembled to secure the airtightness of the electronic control unit 100.

[0006] The electronic control unit 100 thus configured
Then, the coil printed circuit board 107 is the coil terminal 1
06, the coil printed circuit board 107 is fixed to the resin housing 101 via the seal member 109, and the control circuit board 111 connects the connection terminals 112 and the pins 113. Since the lower cover 114 is also fixed to the resin housing 101 and hermetically surrounds them,
It is described that not only the electrical connection with the electrical connector 102 is ensured, but also the waterproofness between the components is ensured.

[0007]

In order to electrically connect the connection terminals on the electrical connector side to the printed wiring on the circuit board, soldering is the cheapest and effective means. However, cracks may occur in the solder joints due to external stress such as thermal distortion around the solder joints due to vibration during driving of the automobile or a sudden change in the ambient temperature, which may eventually lead to a disconnection accident. Therefore, it is important to securely fix the circuit board in order to maintain vibration resistance and to reduce thermal distortion around the solder joint. The present invention is proposed to solve the above problems.

[0008]

In a vehicle-mounted electronic control unit including a connection terminal of an electric connector and a circuit board on which various control elements are mounted, the circuit board is individually mounted on a resin housing of the electronic control unit. The connection terminal fixed via a fixing member and molded on the electric connector side forming a part of the resin housing,
It extends vertically and is soldered to a through hole of the circuit board, and the length of the fixing member is equal to the distance from the mold positioning portion of the connection terminal to the opening of the through hole.

The circuit board is mechanically detachably screwed through a sleeve as a fixing member, and the connection terminal, sleeve, and screw members connected to the circuit board from the resin housing side have similar free lengths. Since the above materials have the same coefficient of thermal expansion, it is possible to suppress the occurrence of thermal distortion at the solder joint and prevent the solder joint from breaking.

The circuit board is mechanically detachably fixed by twisting the head of a plate-like holder as a fixing member, and the connection terminal and the holder members connected to the circuit board from the resin housing side have the same freedom. If they are made of a similar material having a long length, since they have the same coefficient of thermal expansion, the occurrence of thermal distortion at the solder joint can be reduced, and the disconnection of the solder joint can be prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG.
FIG. 3 is a view for explaining the outline of the control unit 1, showing a relative position between the hydraulic unit 2 and the electronic control unit 3, and the electronic control unit 3 is partially shown as a cross-sectional view.
The hydraulic unit 2 includes a hydraulic pump 4 for generating a control hydraulic pressure and a plurality of electronically controlled control valves 5. The electronic control unit 3 includes an electromagnetic coil 6 and connection terminals 8 of an electrical connector 7.
And a circuit board 10 on which various control elements 9 are mounted. Reference numeral 11 denotes a resin housing, which integrally forms the electromagnetic coil 6 and the connection terminals 8 of the electric connector 7 having a plurality of pins.

FIG. 2 shows a first embodiment of the present invention. FIG. 2 is an enlarged view of a portion A in FIG.
Is detachably attached to the resin housing 11 with screws 14 via hollow sleeves 13 inserted into a plurality of blind holes 12 provided on the resin housing 11 side. Screw 1
4 may be a tapping screw.

In the course of this mounting, the connection terminals 8 which are previously embedded integrally with the resin housing 11 are inserted into the through holes 15 of the circuit board 10, and after all the screws 14 have been fastened, Soldering is performed on the through hole 15. In order to surely prevent the screw 14 from being loosened, it is preferable to solder the screw 14 to the periphery of the head or apply an adhesive.

The positions of the mold positioning portion S of the connection terminal 8 and the end of the blind hole 12 are preferably equal to the distance h from the circuit board 10. Further, the connection terminal 8, the sleeve 13, and the screw 14 are made of similar materials.
Brass (C2680, Cu6
(4 to 68%, Zn balance), the thermal expansion coefficient is 17.
Since it is around 5 × 10 ⁻⁶ / ° C., if the distance h of the fixing member is made equal, the concentration of stress on the solder joint due to the thermal strain of the fixing member is suppressed, and the disconnection accident of the solder joint is prevented. Can be.

Further, by appropriately selecting the number of the fixing members, the circuit board 10 is mechanically and firmly fixed. Can be prevented.

In the structure disclosed in Japanese Patent Application Laid-Open No. 8-121323, the pin 113 serves as a fixing member and the control circuit board 111
Since the effect of alleviating the thermal strain cannot be expected and the accuracy of fixing the control circuit board 111 on the same plane is inferior, the soldering of the connection terminals 112 may depend on the order of the soldering operation. Solidification process may leave internal stress. Further, in the present invention, the coil printed circuit board 107 and the control circuit board 111 are integrated with the circuit board 10 in the present invention, so that the cost can be largely reduced.

After the fixing work of the circuit board 10 is completed, a convex protrusion 11a extending along the outer peripheral edge of the resin housing 11 is provided.
Then, the lower cover 16 is mounted by engaging the concave groove 16a of the lower cover 16. An airtightness of the circuit board chamber 17 may be secured by using an elastic seal member instead of the convex protrusion 11a.

FIG. 3 shows a second embodiment of the present invention. The second embodiment uses a holder 18 instead of the sleeve 13 as a fixing member. As shown in FIG. 4 in which a portion B in FIG. 3 is enlarged, holders 18 as fixing members are preliminarily embedded in a plurality of portions of the resin housing 11 of the circuit board 10 by a mold. After passing through the long hole 19 provided in the substrate 10, the lower neck portion 18b is twisted to mechanically fix the circuit substrate 10.

FIG. 5 shows a three-dimensional view of the holder 18. 1
8c is a locking tongue piece when molded, and 18d functions as a flange. Twist the head 18a to lower the neck 1
8b is plastically deformed and locks the side groove portion of the long hole 19 of the circuit board 10 by the slope 18e. It is preferable to conduct soldering test or apply an adhesive around the head of the holder 18 if there is no abnormality.

The position of the mold positioning portion S of the connection terminal 8 and the position of the locking tongue 18c of the holder 18 are preferably equal to the distance h from the circuit board 10. Further, the connection terminal 8 and the holder 18 are made of similar materials, for example, JIS
If brass specified in H 3100 is used, the coefficient of thermal expansion is the same, so that the distance h between the fixing members is made equal to suppress the concentration of stress on the solder joint due to the thermal strain of the fixing member, A disconnection accident at the solder joint can be prevented. Further, by appropriately selecting the number of fixing members, the circuit board 10 is mechanically and firmly fixed, so that a disconnection accident caused by material fatigue of the solder joint due to vibration during running of the automobile can be prevented. .

Next, the results of tests performed to evaluate the effects of the present invention will be described. As a test sample, in the structure of the first embodiment shown in FIG.
Sleeve 13 is m, the connection thickness 0.5 ^phi mm pin 8
And an M5 screw 14 were prepared. On the other hand, as a comparative example of the related art, the distance h shown in FIG.
An electronic control unit 20 having a ^φ mm connection terminal was prepared.

In FIG. 6, the circuit board 10 is fixed to a boss 11b extending from the resin housing 11 with screws 14. Since the coefficient of thermal expansion of the boss 11b is larger than that of the connection terminal made of metal, every time the ambient temperature changes suddenly, a stress is generated at the solder joint of the connection terminal 8 due to the difference in the expansion and contraction length between the boss 11b and the connection terminal 8. The connection terminal 8 of the comparative example A was extended vertically, and the connection terminal 21 of the comparative example B was provided with a U-shaped curved portion in the middle in order to relieve the stress on the solder joint.

The test conditions were JASO D 001-87
A cycle test at an ambient temperature of 120 to -40 ° C, which is equivalent to three types of thermal shock tests in “General rules for environmental testing of electronic devices for automobiles”, is conducted every 100 cycles, and a connection test is performed. The occurrence of cracks in the part was observed. Table 1 summarizes the results after a lapse of 1000 cycles.

[0024]

[Table 1]

Considering the results in Table 1, in the structure in which all the connection terminals 8 in Comparative Example A are vertically extended, the boss 1
Since the thermal expansion coefficients of the connection terminal 1b and the connection terminal 8 are unbalanced, it is estimated that the material of the solder joint has been fatigued. In the structure of Comparative Example B in which all the connection terminals 21 are provided with a well-known U-shaped curved portion, although the energization test was passed,
After molding on the resin housing side, besides processing the U-shaped curved part or setting and molding the connection terminal provided with the U-shaped curved part in advance in a mold using a complicated mechanism, This structure requires more man-hours than the present invention.

In contrast, with the structure of the present invention, as shown in the results of Table 1, the reliability of the solder joint at the repeated thermal shock is high, and in addition, the reliability of the same at the vibration during the running of the automobile. Can also be higher.

[0027]

According to the present invention, the resin housing of the electronic control unit and the circuit board on which the various control elements are mounted are fixed mechanically and removably using a fixing member, and then fixed from the electrical connector or the electromagnetic coil. Since the vertically extending connection terminals were inserted into the through holes of the circuit board and soldered, the vibrations of the automobile while traveling were absorbed by multiple fixing members,
A disconnection accident caused by material fatigue of the solder joint can be prevented. Further, since the soldering process is performed on the circuit board in a stable posture, the internal stress generated in the solidification process of the solder is not left.

Further, by selecting a material similar to the connection terminals and fixing members from the resin housing to the circuit board to make the coefficients of thermal expansion equivalent, even if the ambient temperature surrounding the electronic control unit changes suddenly, the solder joints can be formed. Stress concentration due to thermal strain on the substrate can be avoided. For the same reason, significant cost reduction was achieved by omitting the U-shaped curved portion provided in the middle of the connection terminal to absorb thermal distortion.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a first embodiment of an electronic control unit of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a partial sectional view of a second embodiment of the electronic control unit of the present invention.

FIG. 4 is an enlarged view of a portion B in FIG. 3;

FIG. 5 is a three-dimensional view of the holder of the present invention.

FIG. 6 is a partial cross-sectional view of a conventional electronic control unit as a comparative example.

FIG. 7 is a cross-sectional view of a conventional electronic control unit.

[Explanation of symbols]

 1: control unit 2: hydraulic unit 3: electronic control unit 4: hydraulic pump 5: control valve 6: electromagnetic coil 7: electric connector 8: connection terminal 9: control element 10: circuit board 11: resin housing 12: stop Hole 13: Sleeve 14: Screw 15: Through hole 16: Lower cover 17: Circuit board room 18: Holder 19: Slot

Claims (3)

[Claims] 1. A vehicle electronic control unit including a connection terminal of an electric connector and a circuit board on which various control elements are mounted, wherein the circuit board is connected to a resin housing of the electronic control unit via a fixing member individually attached thereto. The connection terminal, which is fixed and molded on the electrical connector side forming a part of the resin housing, extends vertically and is soldered to a through-hole of the circuit board, and the length of the fixing member and the connection terminal Wherein the distance from the mold positioning portion to the base of the through hole is equal. 2. The circuit board is screwed via a sleeve as a fixing member, and the connection terminal, sleeve, and screw members connected to the circuit board from the resin housing side are made of similar materials and have the same coefficient of thermal expansion. The circuit board fixing structure for an electronic control unit according to claim 1, further comprising: 3. The circuit board is fixed by twisting the head of a plate-shaped holder as a fixing member, and the connection terminal and the holder, which are connected to the circuit board from the resin housing side, are made of similar materials and have the same structure. The circuit board fixing structure for an electronic control unit according to claim 1, wherein the circuit board fixing structure has a coefficient of thermal expansion.