JPH01212740A - Heat treatment for shape memory spring for electronic connector - Google Patents

Abstract

PURPOSE:To maintain characteristics equal to those in the initial stage even after repeated use by subjecting a shape memory spring to shape memory heat treatment and then applying heat treatment removing initial generation power to the above. CONSTITUTION:Shape memory treatment is applied to a shape memory spring consisting of Ni-Ti alloy, etc. Both ends of the resulting U-shaped shape memory spring 8 are inserted into grooves 9A, 9B of a jig 9 and heated in a state where the above spring 8 is provided with the prescribed displacement in the same direction as in the service condition and constrained to undergo inverse transformation, which is air-cooled and subjected to a heat cycle causing martensitic transformation once or plural times. Then, the shape memory spring is detached from the jig 9. By this method, the heat treatment of a shape memory spring for electronic connector in which adverse effects due to repeated use are inhibited can be carried out.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention makes it possible to insert and remove a mating contact with no or low insertion/extraction force by incorporating a shape memory spring into the contact as an actuator. The present invention relates to a method of heat treating the shape memory spring used in electronic connectors.

[Prior art] In recent years, with the progress of integrated circuits (IC, LSI, etc.), electronic I
Industrial technology is also becoming more dense and multi-functional. Along with this, the contact bits of connectors are becoming narrower and the number of contacts is increasing. A problem that inevitably arises here is that when inserting and removing electronic components, boards, etc., the insertion and removal force increases with the increase in the number of poles, and insertion and removal must be performed with unreasonable force. In this way, if the insertion/removal is performed with excessive force, a problem arises in that the contact contact portion may be damaged.

In order to solve this problem and reduce the insertion force during insertion and removal,
2. Description of the Related Art A no-insertion/extraction-force or low-finger type electronic connector incorporating a shape memory spring as a contact actuator has been proposed.

[Problems to be Solved by the Invention] However, when an electronic connector incorporating a shape memory spring as an actuator is repeatedly operated between an uninserted state or a low insertion state and a fitted state, the shape changes. There is a problem that the memory spring gradually deforms in the direction of movement.

If the initial shape of the shape memory alloy spring changes, it will greatly affect the characteristics of the connector, for example, the mating pressure may drop drastically, or
Alternatively, undesirable results may occur, such as failure to achieve sufficient no-insertion/extraction-force or low-insertion/extraction-force conditions.

An object of the present invention is to provide a method of heat treating a shape memory spring for an electronic connector, which can suppress the adverse effects of repeated use of the shape memory spring.

[Means for Solving the Problems] To explain in detail the present invention to achieve the above object, the present invention provides a method for heat treating a shape memory spring for an electronic connector for driving a contact incorporated in a connector housing. After applying memory heat treatment to the shape memory spring in a predetermined shape, the shape memory spring undergoes martensitic transformation and reverse transformation while being restrained by giving a predetermined displacement in the same direction as the shape in use. It is characterized by applying at least one thermal cycle consisting of:

[Function] By applying heat treatment to the shape memory spring in this way, the initial II characteristics can be maintained even after repeated use.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIGS. 1A to 1C show an embodiment of the present invention. A shape memory spring made of Ni-Ti alloy or the like is subjected to memory heat treatment to form a predetermined U-shape.
A U-shaped shape memory spring 8 as shown in Figure (A) is obtained.

I! of the jig 9, as shown in FIG. 2(B), at both ends of the shape memory spring 8. ! 9A, 9B, and while being restrained by applying a predetermined displacement in the same direction as the used shape, heat to reverse transformation, and then air cooling to cause martensitic transformation. One or more thermal cycles are performed. Repeat times. Thereafter, the shape memory spring 8 is removed from the jig 9 to obtain a shape memory spring 8 as shown in FIG. 1(C).

There is a characteristic shown in Figure 2 between the number of repeated uses of a shape memory spring and the force generated per unit deformation m, and as shown in the figure, the decrease in the force generated is large in the initial state of use, and then gradually decreases. become.

In this invention, by applying the above-described heat treatment to the shape memory spring after the heat treatment for shape memory, the initial generated force shown in the section B in FIG. is intended to.

FIG. 3 shows an embodiment of an electronic connector incorporating the shape memory spring described above. The electronic connector 1 of this embodiment has a connector housing 2 made of an insulating material, and a contact chamber 3 is opened and provided in the front of the connector housing 2. In the contact chamber 3, contacts 4.5 are installed in two rows parallel to the longitudinal direction of the connector housing 2. In this embodiment, the contacts 4.5 on both sides are arranged as a pair with their contact portions 4A and 5A facing each other, and their leg portions 4B and 5B are connected to the connector housing 2.
It passes through the bottom of the tube and is led out. The connector housing 2 is provided with partition walls 6.7 protruding from each row of contacts 4.5 for insulating adjacent contacts 4.4 and 5.5. A shape memory spring 8 for driving the contacts 4.5 is disposed between the rows of contacts 4.5.

This shape memory spring 8 has a shape memory spring 8 that is used to remove the initial generated force as described above after shape memory heat treatment.
A heat treatment as shown in C) is given. That is, in this case, since it is used in a state where the distance between both ends is widened compared to the state shown in Fig. 1 (A>), the restraint is applied in the spread state as shown in Fig. 1 (B), and then A thermal cycle of martensitic transformation and reverse transformation is applied at least once.

Such a shape memory spring 8 is provided along the row of contacts 4 and 5 on both sides, and both edges of the curved recess are made of an insulating material.
11 to the contacts 4.5 on each side, so that these contacts 4.5 can be driven simultaneously. The motion transmitting member 10.11 has a structure in which a part of the contacts 4.5 in each row is embedded during molding and is integrally molded into a rectangular parallelepiped shape along the longitudinal direction of the connector housing 2. That is, each contact 4.5 and each motion transmission member 10.11 are integrated when the motion transmission member 10.11 is molded, and each of the motion transmission members io, 1i is supported in the middle of each contact 4.5. It has become. In addition, in integrating each contact 4.5 and each motion transmission member 10.11, means such as press-fitting each contact 4, 5 into each motion transmission member 10.11 may be used.

Each motion transmission member 10.11 has grooves 10A and 11Δ, respectively.
are formed, and shape memory springs 8 are formed in these grooves 10A and 11A.
Both ends are inserted and fixed to connect each motion transmitting member 10.11 to the shape memory spring 8. The motion transmitting member 10.11 is made of a heat-resistant resin (for example, polyphenylene sulfide, polyetherimide, etc.) that has sufficient strength under the usage conditions, and its thickness and width are similar to the shape memory spring 8. It is designed to sufficiently withstand the force of contacts 4 and 5. In this case, if the grooves 10A and 11A of the motion transmission member 10.11 are provided continuously from one end to the other end, the shape memory spring 8 can be slid from one end and attached to the motion transmission member 10.11 after the connector is assembled. Therefore, it is suitable. In addition, the shape memory spring 8 is placed in the groove 10A.

11A, the shape memory spring 8 is attached to the motion transmitting members io, 1 by injecting adhesive into the grooves 10A, 11A, etc.
When integrated into i, the shape memory spring 8 becomes full 10A, 11
This is preferable because separation from A can be prevented.

In this embodiment, the shape memory spring 8 has a transformation point set at 80°C. Therefore, at room temperature, it is a martensite phase and soft, and at 80° C. or higher, it becomes an austenite phase, increasing its rigidity.

4 and 5 are cross-sectional views showing the operation of the electronic connector 1 shown in FIG. 3. FIG. 4 shows the state at room temperature. In this state, the shape memory spring 8 is soft in the martensitic phase and succumbs to the spring pressure of the contacts 4 and 5.
It is pulled outward via the motion transmitting member 10° 11, and as a result, insertion can be performed with low or no insertion/extraction force. Fifth
The figure shows the state in an atmosphere of 80° C. or higher, such as in a burn-in device. In this state, the shape memory spring 8 enters the austenitic state, recovers its initially memorized shape, and draws each contact 4.5 inward via the motion transmission member 10.11, at which time a high contact pressure is applied. can get.

FIG. 6 shows a comparison of the change in contact pressure under actual use (at high temperature) when this electronic connector 1 is used repeatedly at room temperature and high temperature with that of a conventional product.

The test was repeated once from room temperature to high temperature (120° C.) to room temperature. In the figure, the mark X indicates the shape of the U-shaped cross section.
Conventional electronic connector using shape memory spring 8 obtained by memory treatment at 50℃ x 30 min.
Measured values of an electronic connector of the present invention using a shape memory spring 8 subjected to one thermal cycle of martensitic transformation and reverse transformation while being restrained with a strain of 0.5% after being subjected to memory treatment. be.

As is clear from Figure 6, the contact pressure of a conventional electronic connector incorporating a shape memory spring that is not subjected to heat treatment to remove the initial force is reduced by about half after 2000 uses. On the other hand, the electronic connector of the present invention, which incorporates a shape memory spring that has been heat-treated to remove the initial force, shows almost no decrease in contact pressure even after 2,000 uses. According to experiments, when the shape memory spring 8 is subjected to heat treatment for shape memory and then subjected to a heat cycle to remove the initial generated force, if the constraint suspension is small, the number of thermal cycles is increased, and if the constraint suspension is large. The same effect was found to be 19.

[Effects of the Invention] As explained above, in the heat treatment method for shape memory springs for electronic connectors according to the present invention, after the shape memory spring is subjected to shape memory heat treatment, heat treatment is applied to remove the initial generated force, so that the heat treatment is repeated. A shape memory spring that can maintain the same initial characteristics even after use is obtained, and therefore an electronic connector with no insertion/extraction force or low insertion/extraction force that can maintain the same initial characteristics even after repeated use can be obtained.

[Brief explanation of the drawing]

Figures 1 (A) to (C) are explanatory diagrams showing an example of the heat treatment process of the method of the present invention, Figure 2 is a characteristic diagram of the number of repeated uses of the shape memory spring and the force generated per unit deformation m5, FIG. 3 is a cross-sectional perspective view of an embodiment of an electronic connector incorporating a heat-treated shape memory spring of the present invention, and FIGS.
An explanatory diagram showing different operating states of the contacts and the shape memory spring in the electronic connector of the embodiment shown in the figure, FIG. FIG. 4 is a comparison diagram of changes in contact pressure due to repeated use with an electronic connector (referred to as a conventional product) incorporating a shape memory spring that is not subjected to heat treatment according to the present invention. 2... Connector housing, 4.5... Contact, 8... Shape memory spring. Figure 1 ↓ @ Figure 2

Claims (1)

[Claims] In a method of heat treating a shape memory spring for an electronic connector for driving contacts incorporated in a connector housing, the shape memory spring is subjected to memory heat treatment in a predetermined shape, and then the shape memory spring is heated in its use state. At least one thermal cycle consisting of martensitic transformation and reverse transformation is performed in a state where a predetermined displacement is applied and restrained in the same direction as the shape.
A method for heat treating a shape memory spring for an electronic connector, the method comprising: heating a shape memory spring for an electronic connector;