JP5243744B2 - Connector terminal - Google Patents

Description

  The present invention relates to an electrical connection component, mainly a small connector terminal used for transmission of an electrical signal.

  In the automobile industry, advanced electrical equipment for automobiles is being promoted. This is because it is necessary to mount many electronic devices and electrical components in order to improve safety performance, environmental performance, and comfort. This means that the number of circuits connected to each other increases, and the number of connectors and wire harnesses increases accordingly. However, the increase in these electrical components leads to an increase in the weight of the automobile, and in order to deteriorate fuel consumption, the mounted electrical components are required to be smaller and lighter.

  Similarly, in the consumer field, electronic products such as mobile phones, personal computers, AV equipment, and game machines have been improved in performance and size and weight, and the electronic components and connectors used therefor are also reduced in size and weight. Is required.

  In order to reduce the size and weight of electronic components and connectors, it is necessary to make the copper alloy plate material thinner. To compensate for the reduced terminal strength and springiness, the copper alloy used as the material has high strength. It is necessary to apply a copper alloy with strong spring properties. As such a copper alloy, Cu—Ni—Si, Cu—Ni—Sn—P, Cu—Be, Cu—Ti, and the like are known.

JP 2006-16629 A JP 2002-294368 A Japanese Unexamined Patent Publication No. 2000-160312 JP 2006-274289 A

  However, a high-strength copper alloy has poor moldability, and it has been extremely difficult to process it into a small and complicated shape such as a small connector terminal and a next-generation small connector terminal. In particular, when molding the tab part of the male connector terminal and the box part corner of the female connector terminal, the part where the material is bent to suppress the spring back after press molding and obtain the shape and dimensional accuracy It is indispensable to apply a processing method (hereinafter referred to as a “post-notching bending method”) in which a notching process is performed on the material and then bending is performed along the notch. However, this processing method has a problem that the vicinity of the notch portion is work-hardened by notching, so that cracking is likely to occur in subsequent bending. In order to avoid this problem, there is a conventional means of using an alloy with fine crystal grains and good bending workability. However, such an alloy with fine crystal grains is a resistance indicator that is an indicator of reliability of the terminal spring portion. Since the stress relaxation characteristics are inferior, the connector terminal obtained thereby has a drawback that it is difficult to obtain high electrical reliability over a long period of time. Accordingly, it has been extremely difficult to reduce the size and weight of highly reliable electrical connector terminals.

  The present invention has been made by paying attention to the above points, and by using a copper alloy having a special crystal orientation as a material, a connector with high dimensional accuracy and high electrical contact reliability even if it is reduced in size and weight. The purpose is to provide a terminal.

The object is achieved by using a copper alloy plate material having a crystal orientation satisfying the following formulas (1) and (2) as the material of the connector terminal.
I {420} / I ₀ {420}> 1.0 (1)
I {220} / I ₀ {220} ≦ 3.0 (2)
Here, I {420} is the X-ray diffraction intensity of the {420} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {420} is the X-ray diffraction intensity of the {420} crystal plane of the pure copper standard powder. Similarly, I {220} is the X-ray diffraction intensity of the {220} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {220} is the X-ray diffraction intensity of the {220} crystal plane of the pure copper standard powder.

  The copper alloy sheet has an average crystal grain size of 5 to 60 μm. It is preferable that it is 10-60 micrometers, and it is more preferable that it is 15-40 micrometers. Here, the average crystal grain size can be obtained by a cutting method of JIS H0501 by etching after polishing the plate surface (rolled surface), and observing the surface with a microscope. The copper alloy sheet used for the processing material in the present invention is preferably subjected to a surface treatment such as reflow Sn plating.

  Moreover, as said copper alloy, Cu-Ni-Si type (so-called Corson alloy), Cu-Ni-Sn-P type, Cu-Be type (so-called beryl copper), Cu-Ti type (so-called titanium copper), etc. Components can be used. Specifically, the copper alloy of the following compositions is mentioned.

[Cu-Ni-Si system]
In mass%, Ni: 0.7-4.2%, Si: 0.2-1%, or even Fe, Zn, Mg, Sn, Co, Cr, Be, Zr, Ti, Mn, V, Ag, A copper alloy containing one or more of P and B within a total range of 3% or less, and the balance substantially having a composition of Cu

[Cu-Ni-Sn-P system]
In mass%, Ni: 0.1-5%, Sn: 0.1-5%, P: 0.01-0.5%, or even Fe, Zn, Mg, Si, Co, Cr, Be, Zr , Ti, Mn, V, B containing at least one total in a range of 3% or less, copper alloy having the remainder substantially Cu composition

[Cu-Be system]
By mass%, Be: 0.1~5%, Ni : 0.1~2.5%, or even Fe, Zn, Mg, Co, Cr, Z r, Sn, Ti, Mn, V, P, B A copper alloy containing at least one of the above in a total range of 3% or less and the balance substantially having a composition of Cu

[Cu-Ti system]
In mass%, Ti: 0.1 to 5%, or further 3% in total of one or more of Al, Ni, Si, Fe, Zn, Sn, Co, Cr, Be, Zr, Mn, V, P, B Copper alloy containing in the following range, the balance substantially having a composition of Cu

  According to the present invention, since the copper alloy plate material having a special crystal orientation suitable for forming the tab portion and the box portion of the connector terminal is used as the processing material, in the connector terminal that has undergone severe processing by miniaturization and weight reduction. A machined part having no cracks and excellent dimensional accuracy is provided. That is, a thin plate of high strength material that could not be used for a conventional connector terminal can be used as a material for the connector terminal, and an unprecedented small and lightweight connector terminal can be realized. In addition, since the copper alloy having the above crystal orientation has an excellent bending workability, the crystal grain size can be increased to about 5 to 60 μm. The material having greatly improved stress relaxation resistance is provided. Therefore, the connector terminal of the present invention can contribute to the reduction in size and weight of electric / electronic devices, improvement in design flexibility, and improvement in electrical reliability.

<< Texture
In the present invention, a copper alloy plate material adjusted to a texture with a specific crystal orientation is used as a connector terminal processing material.
An X-ray diffraction pattern from a plate surface (rolled surface) of a copper alloy sheet is generally composed of diffraction peaks of four crystal planes {111}, {200}, {220}, {311}, and other crystal planes. The X-ray diffraction intensity from is very small compared to those from these crystal planes. However, the inventors have found that copper alloy sheet materials having a texture with {420} as the main orientation component can be obtained. Japanese Patent Application Nos. 2007-032623, 2007-071550, 2007-147465 and 2007- 157935 (hereinafter, these may be referred to as “prior application”), the detailed production method was clarified. According to detailed examinations by the inventors, the stronger the texture with {420} as the main orientation component, the more convenient it is for forming the tab portion and the box portion of the connector terminal. Thinks as follows.

  There is a Schmid factor as an index indicating the ease of plastic deformation (slip) when an external force is applied in a certain direction of the crystal. When the angle between the direction of the external force applied to the crystal and the normal of the slip surface is φ, and the angle between the direction of the external force applied to the crystal and the slip direction is λ, the Schmid factor is expressed as cos φ · cos λ. The value is in the range of 0.5 or less. A larger Schmid factor (that is, closer to 0.5) means a greater shear stress in the slip direction. Therefore, when an external force is applied to a certain crystal from a certain direction, the larger the Schmid factor (that is, the closer to 0.5), the easier the crystal is deformed. The crystal structure of the copper alloy which is the subject of the present invention is a face centered cubic (fcc). The slip system of the face-centered cubic crystal has a slip plane {111} and a slip direction <110>, and it is known that even in an actual crystal, the larger the Schmid factor, the easier the deformation and the less work hardening.

  FIG. 3 shows a standard inverse pole figure representing the Schmid factor distribution of face-centered cubic crystals. The Schmid factor in the <120> direction is 0.490, close to 0.5. That is, when an external force is applied in the <120> direction, the face-centered cubic crystal is very easily deformed. The Schmid factors in the other directions are 0.408 in the <100> direction, 0.445 in the <113> direction, 0.408 in the <110> direction, 0.408 in the <112> direction, and 0 in the <111> direction. .272.

  The texture having {420} as the main orientation component means a texture having a large amount of crystals in which the {420} plane, that is, the {210} plane is substantially parallel to the plate surface (rolled surface). In a crystal whose principal orientation plane is the {210} plane, the direction (ND) perpendicular to the plate surface is the <120> direction, and its Schmitt factor is close to 0.5, so that the transformation to ND is very easy. There is little work hardening. On the other hand, the general rolling texture of each type of copper alloy conventionally used for connector terminals has {220} as the main orientation component. In this case, the {220} plane, that is, the {110} plane, There is a large proportion of crystals that are substantially parallel to the plate surface (rolled surface). A crystal whose principal orientation plane is the {110} plane has ND in the <110> direction and its Schmitt factor is about 0.4, so that it is ND compared to a crystal whose principal orientation plane is the {210} plane. The work hardening accompanying the deformation to becomes larger. Moreover, the general recrystallization texture of each type of copper alloy conventionally used for connector terminals has {311} as the main orientation component. The crystal whose principal orientation plane is the {311} plane has the ND <113> direction and its Schmitt factor is about 0.45, so that it is still ND compared with the crystal whose principal orientation plane is the {210} plane. The work hardening accompanying the deformation to becomes larger.

  In the “bending method after notching”, the degree of work hardening at the time of deformation in the direction perpendicular to the plate surface (ND) is extremely important. This is because notching is exactly a deformation to ND, and the degree of work hardening of the portion where the plate thickness is reduced by notching largely governs the bending workability when bent along the notch. In the case of a texture having {420} as the main orientation component satisfying the expression (1), work hardening by notching is smaller than that of a conventional rolled texture or recrystallized texture of a copper alloy. This is considered to be a factor that significantly improves the bending workability in the “post-bending method”.

  Further, in the case of a texture having {420} as a main orientation component that satisfies the expression (1), in a crystal whose main orientation plane is a {210} plane, There are <120> direction and <100> direction, which are orthogonal to each other. Actually, it has been confirmed that the rolling direction (LD) is the <100> direction and the direction perpendicular to the rolling direction (TD) is the <120> direction. As a specific crystal direction, for example, in a crystal whose main orientation plane is the (120) plane, LD is the [001] direction and TD is the [−2, 1, 0] direction. The Schmid factor of such crystals is LD of 0.408 and TD of 0.490. On the other hand, in the case of a crystal whose principal orientation plane is the {110} plane as in the conventional rolling texture of a copper alloy, LD is in the <112> direction and TD is in the <111> direction, and its Schmitt factor. LD is 0.408 and TD is 0.272. In the case of a crystal whose principal orientation plane is the {113} plane as in the conventional recrystallization texture of a copper alloy, LD is in the <112> direction and TD is in the <110> direction, and the Schmitt factor is , LD is 0.408, and TD is 0.408. Thus, looking at the Schmid factor of LD and TD, in the case of a texture having {420} as the main orientation component, the deformation in the plate surface is compared with the rolling texture or recrystallized texture of the conventional copper alloy. Can be said to be easy. This point is also considered to be advantageous in preventing cracking in bending after notching.

  In the bending process of the metal plate, the crystal orientation of each crystal grain is different, so that there is a crystal grain that is not easily deformed but a crystal grain that is easily deformed during bending and a crystal grain that is difficult to deform. As the degree of bending increases, the deformable crystal grains become more preferentially deformed, and micro unevenness is generated on the surface of the bent part of the plate due to uneven deformation among the crystal grains. This develops into wrinkles, and in some cases leads to cracks (breaks). As described above, the metal plate having a texture satisfying the expression (1) is more likely to be deformed into ND and more easily deformed in the plate surface than the conventional metal plate. It can be inferred that this leads to a marked improvement in the bending workability after notching and the normal bending workability even if the crystal grains are not particularly refined.

According to the study by the inventors, such crystal orientation can be specified by the following formula (1).
I {420} / I ₀ {420}> 1.0 (1)
Here, I {420} is the X-ray diffraction intensity of the {420} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {420} is the X-ray diffraction intensity of the {420} crystal plane of the pure copper standard powder. In the face-centered cubic X-ray diffraction pattern, {420} plane reflection occurs, but {210} plane reflection does not occur, so the {210} plane crystal orientation is evaluated by {420} plane reflection. Those satisfying the following formula (1) ′ are more preferable.
I {420} / I ₀ {420}> 1.5 (1) ′

The texture having {420} as the main orientation component is formed as a recrystallized texture by solution treatment as disclosed in the previous application. However, cold rolling after the solution treatment is extremely effective for increasing the strength of the copper alloy sheet. As this cold rolling, intermediate cold rolling and finish cold rolling are applied. As the cold rolling rate increases, a rolling texture having {220} as a main orientation component develops. As the {220} orientation density increases, the {420} orientation density decreases. However, the rolling rate may be adjusted so that the formula (1), preferably the formula (1) ′ is maintained. However, if the texture having {220} as the main azimuth component is developed too much, the workability may be deteriorated. Therefore, it is preferable to satisfy the following formula (2). Further, in order to achieve both “strength” and “bending workability” at a high level with a good balance, it is more preferable to satisfy the following expression (2) ′.
I {220} / I ₀ {220} ≦ 3.0 (2)
0.5 ≦ I {220} / I ₀ {220} ≦ 3.0 (2) ′
Here, I {220} is the X-ray diffraction intensity of the {220} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {220} is the X-ray diffraction intensity of the {220} crystal plane of the pure copper standard powder.

<Average crystal grain size>
The smaller the average crystal grain size, the more advantageous the bending workability is. However, when the average crystal grain size is too small, the stress relaxation resistance tends to deteriorate. As a result of various studies, if the average crystal grain size is finally a value of 5 μm or more, preferably a value exceeding 10 μm, it is easy to secure a stress relaxation resistance level that is satisfactory even for use in a vehicle-mounted connector, which is suitable. . However, if the average crystal grain size becomes too large, the surface of the bent part is likely to be rough, which may lead to a decrease in bending workability. Therefore, the range of 60 μm or less is desirable. More preferably, it is in the range of 15-40 μm.

"composition"
The connector terminal of the present invention includes Cu—Ni—Si (so-called Corson alloy), Cu—Ni—Sn—P, Cu—Be (so-called beryl copper), Cu—Ti (so-called titanium copper), etc. Component-based materials can be used, but any fcc type copper alloy having a crystal orientation satisfying the formula (1) can be used without limitation. The content range of each component element is as described above, and details thereof are disclosed in the prior application.

<Manufacture of copper alloy sheet>
The copper alloy sheet material having the unique crystal orientation applicable to the connector terminal of the present invention can be manufactured, for example, by the following manufacturing process.
・ Cu-Ni-Si system “Melting / Casting → Hot Rolling → Cold Rolling → Solution Treatment → Intermediate Cold Rolling → Aging Treatment → Finish Cold Rolling → Low Temperature Annealing”
・ Cu-Ni-Sn-P system "Melting / Casting-> Hot rolling-> Cold rolling-> Recrystallization annealing-> (Aging treatment)-> Finishing cold rolling-> (Low temperature annealing)
・ Cu-Be series “Melting / Casting → Hot Rolling → Cold Rolling → Solution Treatment → Finish Cold Rolling → (Aging Treatment)”
・ Cu-Ti system “Melting / Casting → Hot Rolling → Cold Rolling → Solution Treatment → Finish Cold Rolling → Aging Treatment”

  Among these steps, in particular, hot rolling, cold rolling before solution treatment (in the Cu-Ni-Sn-P system, cold rolling before recrystallization annealing), solution treatment (Cu-Ni-Sn-P system). In the case of recrystallization annealing), and a sheet material having the above-mentioned unique crystal orientation by devising cold rolling after solution treatment (cold rolling after recrystallization annealing in the Cu-Ni-Sn-P system) Can be made separately. Other steps may be performed in accordance with ordinary methods. Although the specific manufacturing method is disclosed in detail in the above-mentioned prior application, the characteristic steps are summarized as follows.

(Hot rolling)
Usually, the hot rolling of each of the above-described copper alloys is performed by a method of rolling in a high temperature range of 700 ° C. or higher or 750 ° C. or higher and quenching after the rolling is finished in order not to generate precipitates during rolling. Is called. However, it is difficult to produce a copper alloy sheet having a unique texture applicable in the present invention under such common-sense hot rolling conditions. That is, when such hot rolling conditions are adopted, a copper alloy sheet having {420} in the main orientation cannot be manufactured with good reproducibility even if the conditions of the post-process are changed over a wide range. As a result of detailed studies by the inventors, the first rolling pass was performed in a temperature range of 700 ° C. or higher, and a temperature range of less than 700 ° C. to 400 ° C. (in the Cu—Ti system, less than 700 ° C. to 500 ° C.). Therefore, it is important to adopt the hot rolling conditions in which rolling is performed at a rolling rate of 40% or more (30% or more in the case of Cu-Ti system).

  When the slab is hot-rolled, by performing the first rolling pass at a temperature higher than 700 ° C. where recrystallization is likely to occur, the cast structure is destroyed, and the components and the structure can be made uniform. However, rolling at an excessively high temperature is not preferable because cracks may occur at locations where the melting point is lowered, such as segregated locations of alloy components. In order to ensure complete recrystallization during the hot rolling process, the first rolling pass is performed in a temperature range lower by 30 ° C. than the solidus temperature. It is extremely effective to perform rolling at a rolling rate of 60% or more in a temperature range of 700 ° C. or higher. This further promotes tissue homogenization. However, in order to obtain 60% in one pass, a large rolling load is required, so that a rolling rate of 60% or more in total can be secured by dividing into multiple passes. Further, in the present invention, a rolling rate of 40% or more (30% or more in the Cu-Ti system) in a temperature range of less than 700 ° C to 400 ° C where the rolling distortion is likely to occur (less than 700 ° C to 500 ° C in the Cu-Ti system). It is important to ensure. Thereby, a part of precipitates are generated, and a recrystallized texture having {420} as a main orientation component is easily formed by a combination of “cold rolling + solution treatment” in the subsequent step. Also in this case, several passes of rolling can be performed in the above temperature range of less than 700 ° C. It is more effective to set the final pass temperature of hot rolling to 600 ° C. or lower. The total rolling rate in the hot rolling may be about 80 to 97%.

Here, the rolling rate ε (%) in each temperature range is calculated by the equation (3).
ε = (t ₀ −t ₁ ) / t ₀ × 100 (3)
For example, the plate thickness of the slab used for the first rolling pass performed between 950 and 700 ° C. is 120 mm, and rolling is performed in a temperature range of 700 ° C. or higher (returning to the furnace during the process may be performed again) The sheet thickness is 30 mm at the end of the last rolling pass carried out at a temperature of 700 ° C. or higher, and the rolling is continued continuously, and the final pass of hot rolling is in the range of less than 700 ° C. to 400 ° C. It is assumed that a hot rolled material having a thickness of 10 mm is finally obtained. In this case, the rolling rate of the rolling performed in the temperature range of 950 ° C. to 700 ° C. is (120−30) / 120 × 100 = 75 (%) according to the equation (3). Moreover, the rolling rate in the temperature range of less than 700 ° C. to 400 ° C. is (30−10) /30×100=66.7 (%) according to the same expression (3).

[Cold rolling before solution treatment (Cold rolling before recrystallization annealing in Cu-Ni-Sn-P system)]
When rolling the hot-rolled sheet, it is important that the cold rolling performed at this stage has a rolling rate of 85% or more (80% or more for Cu-Be type and Cu-Ti type), and 90% or more. More preferably. By subjecting the material processed at such a high rolling rate to solution treatment or recrystallization annealing in the next step, it becomes possible to form a recrystallized texture having {420} as the main orientation component. In particular, the recrystallization texture greatly depends on the cold rolling rate before recrystallization. Specifically, the crystal orientation with {420} as the main orientation component hardly generates when the cold rolling rate in this step is 60% or less, and increases the cold rolling rate in the region of about 60 to 80%. Along with this, it gradually increases, and when the cold rolling rate exceeds about 80%, it suddenly increases. In order to obtain a crystal orientation in which the {420} orientation is sufficiently dominant, it is necessary to ensure the high cold rolling rate. The upper limit of the cold rolling rate is inevitably restricted by the mill power or the like, and thus need not be specified. However, good results are likely to be obtained at approximately 98% or less from the viewpoint of preventing edge cracks and the like.

  In addition, after hot rolling, before the solution treatment or recrystallization annealing, a step of performing cold rolling one or more times with intermediate annealing is not adopted. When the intermediate annealing is performed after the hot rolling and before the solution treatment, the recrystallized texture having {420} as a main orientation component formed by the solution treatment is significantly weakened.

[Solution treatment (recrystallization annealing in Cu-Ni-Sn-P system)]
The conventional solution treatment is mainly aimed at “re-solution of solute elements in the matrix” and “recrystallization”, and the conventional recrystallization annealing is mainly aimed at “recrystallization”. In this case, an important objective is to “form a recrystallized texture having {420} as the main orientation component”. This heat treatment is desirably performed at a furnace temperature of 700 to 850 ° C. (600 to 750 ° C. for Cu—Ni—Sn—P system, 700 to 900 ° C. for Cu—Be system). If the temperature is too low, recrystallization is incomplete and in the case of a solution treatment, the solute elements are not sufficiently dissolved. If the temperature is too high, the crystal grains become coarse. In either case, it is difficult to finally obtain a high-strength material excellent in bending workability.

  In addition, it is desirable to perform the heat treatment by setting the heat treatment temperature and time so that the average grain size of recrystallized grains (not considering twin boundaries as crystal grain boundaries) is 5 to 60 μm. It is more preferable to adjust so that it may become 10-60 micrometers, and it is still more preferable to set it as 15-40 micrometers. When the recrystallized grain size becomes too fine, the recrystallized texture having {420} as the main orientation component becomes weak. It is also disadvantageous in improving the stress relaxation resistance. If the recrystallized grain size becomes too large, surface roughness of the bent portion is likely to occur. The recrystallized grain size varies depending on the cold rolling rate and chemical composition before the solution treatment, but by previously obtaining the relationship between the solution treatment heat pattern and the average crystal grain size for each alloy by experiment, Heat treatment conditions can be set. Specifically, the optimum time can be found in the temperature range of about 10 seconds to 10 minutes in the case of solution treatment and in the range of seconds to hours in the case of recrystallization annealing.

[Cold rolling after solution treatment (Cold rolling after recrystallization annealing in Cu-Ni-Sn-P system)]
The strength level is improved by cold rolling at this stage. However, as the cold rolling rate increases, a rolling texture having {220} as the main orientation component develops. If the rolling rate is too high, the rolling texture in the {220} orientation becomes relatively dominant, and crystal orientation in which strength and bending workability are compatible at a high level cannot be realized. As a result of detailed studies by the inventors, cold rolling at this stage is performed in the range of 0 to 50% rolling ratio (30 to 80% for the Cu—Ni—Sn—P system, 0 to 65% for the Cu—Be system). ) Is important. Thereby, the crystal orientation satisfying the formula (1) can be maintained. Here, “rolling rate 0%” means a case where rolling is not performed.

<Processing into connector terminals>
The connector terminal of the present invention uses the above-described copper alloy plate material having a specific crystal orientation (may be subjected to surface treatment such as reflow Sn plating) as a workpiece, for example, by continuous press molding. Manufactured. The press is a processing method in which a pair of upper and lower molds is generally used and a workpiece is sandwiched between the molds. Continuous press molding uses a tandem press in which a plurality of independent presses are arranged continuously and a feeding device that conveys the workpiece is placed between them, or a transfer press in which a plurality of presses and feeding devices are integrated. In this method, a terminal is formed by continuously performing a plurality of processes such as die cutting, notching and bending.

  FIG. 1 schematically shows the shape of an intermediate product at a stage where a connector terminal portion is formed by continuously press-molding a strip of copper alloy sheet material. Each connector terminal portion 10 is still connected by a pilot portion 11. The connector terminals are female, and each terminal has a box portion 21 and a crimping portion 22. The box part 21 is formed by being bent at the box bending part 31, and a spring part 32 is provided inside the box part 21. When the connector terminal is continuously press-molded, as shown in this figure, the longitudinal direction of the connector terminal is perpendicular to the longitudinal direction (LD) of the strip of the copper alloy sheet material to be processed (TD). (So-called “horizontal chain method”). In addition, continuous press molding may be performed in such an arrangement that the longitudinal direction of the connector terminals coincides with the LD (so-called “vertical chain method”).

  When forming the tab portion of the male connector terminal or the box portion of the female connector terminal, the “bending method after notching” is applied to the bending process. When forming connector terminals using the horizontal chain method, the notch direction (ie, the direction parallel to the grooves) required for bending to form the tabs and boxes of the terminals is TD, and the strength of the workpiece However, it is possible to form the tab portion and the box portion of the terminal with high dimensional accuracy by making a notch having a depth of 1/7 to 1/2 with respect to the plate thickness.

  If the copper alloy plate material adjusted to the above specific crystal orientation is used as a workpiece, for example, a tab portion of a connector terminal or the like can be formed without using a thin plate material having a plate thickness of 0.08 to 0.30 mm. The box part can be formed, and a small connector terminal that cannot be stably formed into a sound component with a conventional copper alloy sheet can be obtained.

  A copper alloy plate material having a composition shown in Tables 1 and 2 and having a thickness of 0.15 mm was manufactured by a method satisfying the conditions described in the above-mentioned "Manufacture of a copper alloy plate material" (example of the present invention) and a method deviating from the conditions. . The balance of the elements described in Tables 1 and 2 is Cu. The characteristics of these plate materials were evaluated and evaluated as follows. In Table 2, in the columns of tensile strength, bending workability and stress relaxation rate, LD and TD mean the longitudinal direction of the test piece.

(Grain structure)
The plate surface (rolled surface) of the test material was polished and etched, the surface was observed with an optical microscope, and the average crystal grain size was measured by the cutting method of JIS H0501.

[X-ray diffraction intensity]
A sample whose plate surface (rolled surface) was polished with # 1500 water-resistant paper was prepared, and using an X-ray diffractometer (XRD), Mo-Kα rays, tube voltage 20 kV, tube current 2 mA conditions Then, the reflection diffraction surface intensity of the {420} plane was measured for the polished surface. On the other hand, using the same X-ray diffractometer as described above, the X-ray diffraction intensity of the {420} plane of pure copper standard powder was measured under the same measurement conditions as described above. Using these measured values, the X-ray diffraction intensity ratio I {420} / I ₀ {420} shown in the formula (1) and the X-ray diffraction intensity ratio I {220} shown in the formula (2) are used. / I ₀ {220} was obtained.

〔conductivity〕
The conductivity was measured according to JIS H0505.
〔Tensile strength〕
An LD tensile test piece (JIS No. 5) was collected from each plate material, a tensile test based on JIS Z2241 was performed with the number of tests n = 3, and the tensile strength was determined by the average value of n = 3.

[Stress relaxation characteristics]
A bending test piece (width: 10 mm) having a longitudinal direction of TD was taken from each test material, and arch-bent was performed so that the surface stress at the center in the longitudinal direction of the test piece was 80% of the 0.2% proof stress. Fixed in state. The surface stress is determined by the following equation.
Surface stress (MPa) = 6 Etδ / L ₀ ²
However,
E: Elastic modulus (MPa)
t: sample thickness (mm)
δ: Deflection height of sample (mm)

The stress relaxation rate was calculated using the following equation from the bending habit after holding the test piece in this state at a temperature of 150 ° C. in the atmosphere for 1000 hours.
Stress relaxation rate (%) = (L ₁ −L ₂ ) / (L ₁ −L ₀ ) × 100
However,
L ₀ : Length of the jig, that is, horizontal distance (mm) between the sample ends fixed during the test
L ₁ : Sample length at the start of the test (mm)
L ₂ : Horizontal distance between the sample ends after the test (mm)
Those having a stress relaxation rate of 5% or less are evaluated as having high durability as in-vehicle connectors.

[Bending workability]
A bending test piece having a longitudinal direction of LD and a bending test piece of TD (both 10 mm in width) were sampled from each test material, and a 90 ° W bending test in accordance with JIS H3110 was performed. By observing the surface and cross section of the bent portion of the test piece after the test with an optical microscope at a magnification of 100 times, the minimum bending radius R at which no crack is generated is obtained, and this is divided by the thickness t of the specimen. Thus, R / t values of LD and TD were obtained. The LD and TD of each test material were carried out with n = 3, and the result of the test piece with the worst result among n = 3 was adopted to display the R / t value.

  Each copper alloy sheet material is subjected to reflow Sn plating (plating thickness: 1.0 μm, Cu underlayer thickness: 0.7 μm), and then a female connector terminal (caliber 0.64 mm) having the shape shown in FIG. And produced by the horizontal chain method. However, at the box bending portion of the female connector terminal, bending was performed after notching (grooving) with a depth of 30 μm in the cross-sectional shape shown in FIG. 2 before bending. Further, the space between the spring portion and the box portion was adjusted so that the spring load when the male connector terminal was inserted into the female connector terminal was 4N. In addition, about the copper alloy board | plate material after this reflow Sn plating, it has confirmed that a metal structure (X-ray diffraction intensity ratio and average crystal grain size) is not different from before reflow Sn plating.

[Connector terminal moldability]
By observing the surface and cross section of the bent portion of the female connector terminal of the obtained female connector with an optical microscope at a magnification of 100 times, the presence or absence of cracks is judged. Recognized items were indicated as “x”. In addition, what fractured | ruptured in the box bending part was displayed as "break". The survey was conducted with n = 3, and the result of the connector terminal with the worst result among n = 3 was adopted to evaluate “○”, “×”, “Break”. It was determined to pass.

[Compound environment test]
In order to evaluate the electrical reliability of the connector terminals, a combined environmental test was conducted. A male connector terminal made of a C2600 reflow Sn plating material (plating thickness: 1.0 μm, Cu underlayer thickness: 0.7 μm) having a thickness of 0.15 mm was fitted to the female connector terminal, and “80 ° C. × 30 “Min hold → −40 ° C. × 30 min hold” is one cycle, and 1000 cycles of a combined environmental test in which vibration is applied at each of the two holding temperatures at an acceleration of 3 G and a sweep frequency of 50 Hz. After the test, the contact resistance of the terminal fitting portion was measured. The results are shown in Tables 3 and 4. However, this test was not carried out for those that could not be molded into the terminal shape due to breakage at the box bending part during terminal processing, and the table shows that the test was not performed.
These results are shown in Tables 3 and 4.

  As can be seen from Table 3, the present invention example employs a copper alloy sheet material having a crystal orientation satisfying the formula (1) and a high strength of tensile strength of 600 MPa or more as a work material. Cracks at the box bent part of the connector terminal are not confirmed. Furthermore, because the copper alloy plate material has an excellent characteristic that the stress relaxation rate of TD, which is important in applications such as in-vehicle connectors, is 5% or less, the obtained connector terminal is 1 mΩ even after the composite environmental test. It exhibits the following low contact resistance and has high electrical reliability over a long period of time.

  On the other hand, as shown in Table 4, the comparative example employs an average crystal grain size or a copper alloy sheet that does not satisfy the definition of the formula (1) as a workpiece, and all the comparative female connectors Cracks were confirmed in the terminal box bent part, and in some comparative examples, the box bent part was broken and the terminal shape could not be maintained. Furthermore, the contact resistance after the combined environmental test exceeded 4 mΩ at all terminals because the box part was opened at the end of the test due to the cracking of the box bending part and the stress relaxation rate was as high as 5% or more. Therefore, satisfactory electrical reliability could not be obtained.

The figure which shows typically the shape of the intermediate product of the stage which formed the connector terminal part by carrying out continuous press molding of the strip | belt of a copper alloy board | plate material. The figure which shows the cross-sectional shape of the notch formed in the site | part which performs a box bending process in an Example. Standard inverse pole figure showing Schmid factor distribution of face-centered cubic crystal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Connector terminal part 11 Pilot part 21 Box part 22 Crimp part 31 Box bending part 32 Spring part

Claims (8)

In mass%, Ni has a composition of 0.7 to 4.2%, Si: 0.2 to 1%, the balance being Cu and inevitable impurities, and satisfies the following formulas (1) and (2) A copper alloy plate having a crystal orientation and an average crystal grain size of 5 to 60 μm and having a plate thickness of 0.08 to 0.30 mm is used as a material, and this is 1/7 to 1/2 of the plate thickness. A connector terminal that has a notch of depth and bends along the notch.
I {420} / I ₀ {420}> 1.0 (1)
I {220} / I ₀ {220} ≦ 3.0 (2)
Here, I {420} is the X-ray diffraction intensity of the {420} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {420} is the X-ray diffraction intensity of the {420} crystal plane of the pure copper standard powder. Similarly, I {220} is the X-ray diffraction intensity of the {220} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {220} is the X-ray diffraction intensity of the {220} crystal plane of the pure copper standard powder.   The copper alloy further contains one or more of Fe, Zn, Mg, Sn, Co, Cr, Be, Zr, Ti, Mn, V, Ag, P, and B in a total range of 3% or less. Connector terminals as described in 1. In mass%, Ni has a composition of 0.1 to 5%, Sn: 0.1 to 5%, P: 0.01 to 0.5%, the balance being Cu and inevitable impurities. ) And a crystal orientation satisfying the formula (2), and a copper alloy plate material having an average crystal grain size of 5 to 60 μm and a thickness of 0.08 to 0.30 mm is used as a raw material. A connector terminal formed by inserting a notch having a depth of 1/7 to 1/2 and bending along the notch.
I {420} / I ₀ {420}> 1.0 (1)
I {220} / I ₀ {220} ≦ 3.0 (2)
Here, I {420} is the X-ray diffraction intensity of the {420} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {420} is the X-ray diffraction intensity of the {420} crystal plane of the pure copper standard powder. Similarly, I {220} is the X-ray diffraction intensity of the {220} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {220} is the X-ray diffraction intensity of the {220} crystal plane of the pure copper standard powder.   The connector according to claim 3, wherein the copper alloy further contains one or more of Fe, Zn, Mg, Si, Co, Cr, Be, Zr, Ti, Mn, V, and B in a total range of 3% or less. Terminal. In mass%, Be: 0.1-5%, Ni: 0.1-2.5%, the balance is Cu and inevitable impurities, and satisfies the following formulas (1) and (2) A copper alloy plate having a crystal orientation and an average crystal grain size of 5 to 60 μm and having a plate thickness of 0.08 to 0.30 mm is used as a material, and this is 1/7 to 1/2 of the plate thickness. A connector terminal that has a notch of depth and bends along the notch.
I {420} / I ₀ {420}> 1.0 (1)
I {220} / I ₀ {220} ≦ 3.0 (2)
Here, I {420} is the X-ray diffraction intensity of the {420} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {420} is the X-ray diffraction intensity of the {420} crystal plane of the pure copper standard powder. Similarly, I {220} is the X-ray diffraction intensity of the {220} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {220} is the X-ray diffraction intensity of the {220} crystal plane of the pure copper standard powder.   The connector according to claim 5, wherein the copper alloy further contains one or more of Fe, Zn, Mg, Co, Cr, Zr, Sn, Ti, Mn, V, P, and B in a total range of 3% or less. Terminal. In mass%, Ti has a composition of 0.1 to 5%, the balance is Cu and inevitable impurities, has a crystal orientation satisfying the following formulas (1) and (2) , and an average crystal grain size is A copper alloy plate material having a thickness of 5 to 60 μm and a thickness of 0.08 to 0.30 mm is used as a material, and a notch having a depth of 1/7 to 1/2 is added to the thickness of the copper alloy plate material. Connector terminals that are bent.
I {420} / I ₀ {420}> 1.0 (1)
I {220} / I ₀ {220} ≦ 3.0 (2)
Here, I {420} is the X-ray diffraction intensity of the {420} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {420} is the X-ray diffraction intensity of the {420} crystal plane of the pure copper standard powder. Similarly, I {220} is the X-ray diffraction intensity of the {220} crystal plane on the plate surface of the copper alloy sheet, and I ₀ {220} is the X-ray diffraction intensity of the {220} crystal plane of the pure copper standard powder.   The copper alloy further contains one or more of Al, Ni, Si, Fe, Zn, Sn, Co, Cr, Be, Zr, Mn, V, P, and B in a total range of 3% or less. Connector terminals as described in 1.

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