Patent Description:
As a probe pin for inspecting a BGA type semiconductor IC, there is a contact for an electronic device disclosed in Patent Document <NUM>, for example.

That is, as illustrated in <FIG>, there is a probe pin for inspecting the semiconductor IC <NUM> by coming into contact with a ball-like lead <NUM> provided on the bottom surface of the semiconductor IC <NUM>. As illustrated in <FIG>, a contact part <NUM>, cut out into a substantially V shape, in an upper contact pin <NUM> comes into contact with the ball-like lead <NUM> for electrical connection, so that the probe pin can inspect the semiconductor IC <NUM>.

Further prior art documents are <CIT>, <CIT>, <CIT>, <CIT>, non-patent literature <NPL>, <CIT>, <CIT>, <CIT> and <CIT>.

<CIT> discloses the preambles of independent claims <NUM>, <NUM> and <NUM>.

However, in the upper contact pin <NUM>, the lead <NUM> merely comes into contact with the contact surface of the substantially V shaped contact part <NUM>. As a result, an oxide film formed on the surface of the lead <NUM> cannot be reliably scraped off, causing contact failure to easily occur and variation in inspection accuracy to easily occur, which has been problematic.

In view of the above problem, it is an object of the present invention to provide a probe pin in which contact failure hardly occurs and has uniform inspection accuracy. This object is achieved by the subject matter of the independent claims. Further advantageous modifications and embodiments of the invention are the subject matter of the dependent claims. Aspects of the invention are set out below.

A probe pin according to one aspect of the present invention as defined in one of claims <NUM>, <NUM> and <NUM>, is a probe pin including: an elastic part extending and contracting along a center line; a first contact disposed on one side of the center line and having a rectangular cross section; and a second contact disposed on the other side of the center line and having a rectangular cross section, the probe pin being where the first contact and the second contact are supported so as to be reciprocable via the elastic part and are electrically connected to each other, and it is configured such that a contact surface of at least one of the first contact and the second contact is an inclined surface inclined so as to descend along a thickness direction.

According to the above aspect of the present invention, when a ball solder comes into contact with the inclined contact surface of the contact, the ball solder slides on the contact surface, so that the oxide film of the ball solder is scraped off. Therefore, contact failure hardly occurs, and probe pins having no variation in inspection accuracy can be obtained.

Before continuing with the description of the present invention, the same reference numerals are provided to the same parts in the accompanying drawings.

Hereinafter, a first comparative example not claimed will be described in detail with reference to the drawings.

A probe pin will be described with reference to the attached drawings of <FIG>.

In the following description, in order to describe the configuration shown in the drawing, terms indicating directions such as "upper", "lower", "left", and "right", in addition to "X direction", "Y direction", and "Z direction", and other terms including those terms will be used. The purpose of using these terms is to facilitate understanding of the embodiments and comparative examples through the drawings. Accordingly, those terms do not necessarily indicate directions used at the time of actually using the embodiments of the present invention. A technical scope of the invention recited in the claims shall not be restrictively interpreted by using those terms.

As illustrated in <FIG>, the probe pin <NUM> according to the first comparative example not claimed includes a coil spring <NUM> as an example of an elastic part, a first plunger <NUM>, and a second plunger <NUM>. Each of the first and second plungers <NUM>, <NUM> has electrical conductivity, and is formed by, for example, an electroforming method. The coil spring <NUM> expands and contracts along a center line. A first contact <NUM> is disposed on one side on the center line and has a rectangular cross section. A second contact <NUM> is disposed on the other side on the center line and has a rectangular cross section. The first contact <NUM> and the second contact <NUM> are supported so as to be reciprocable via the coil spring <NUM> and are electrically connected to each other as a probe pin <NUM>.

The coil spring <NUM> is formed of carbon steel or stainless steel, for example. As illustrated in <FIG> and <FIG>, an inner diameter of the coil spring <NUM> is slightly larger than the width dimension (X1-X2 direction) of a clamped part <NUM> of the first plunger <NUM>, which will be described later. The inner diameter of the coil spring <NUM> is slightly larger than the width dimension (Y1-Y2 direction) of each of the first and second elastic pieces <NUM>, <NUM> provided on the second plunger <NUM>, which will be described later. Further, an outer diameter of the coil spring <NUM> is mostly the same as the width dimension (X1-X2 direction) of each of the retaining parts <NUM>, <NUM> of the first plunger <NUM>. The outer diameter of the coil spring <NUM> is mostly the same as the width dimension (Y1-Y2 direction) of each of the retaining parts <NUM>, <NUM> of the second plunger <NUM>.

Note that the length dimension (Z1-Z2 direction) of the coil spring <NUM> may be adjusted such that the coil spring <NUM> is constantly compressed as required in the state illustrated in <FIG>, <NUM>(A) and <NUM>(B), or may be adjusted such that the coil spring <NUM> comes into a free state without compression.

As illustrated in <FIG> and <FIG>, the first plunger <NUM> has a flat plate shape extending along the Z1-Z2 direction and is formed to have mostly the same thickness dimension. The first plunger <NUM> is made up of the clamped part <NUM> and a first contact part <NUM> continuous from the clamped part <NUM> in the Z1 direction. In the first plunger <NUM>, the surface along the X1-X2 direction is a main surface, and the surface along the Y1-Y2 direction orthogonal to the main surface is a side surface.

The clamped part <NUM> has a rectangular guide groove <NUM> penetrating the main surface. The guide groove <NUM> is formed along the Z1 direction from the lower end edge of the clamped part <NUM>. The width dimension (X1-X2 direction) of the guide groove <NUM> is larger than a thickness dimension (X1-X2 direction) of the second plunger <NUM>.

The first contact part <NUM> has the first contact <NUM> at its tip (the upper end in <FIG>). The first contact <NUM> has a substantially V shape as seen from the main surface. Further, as illustrated in <FIG>, a contact surface of the first contact <NUM> is constituted by an inclined surface which is inclined so as to descend in the Y2 direction to form a wiping surface. An inclination angle is preferably <NUM> degree to <NUM> degrees, particularly preferably <NUM> degrees to <NUM> degrees. This is because, when the inclination angle is less than <NUM> degree, an oxide film of the ball solder cannot be efficiently scraped off, and when the inclination angle exceeds <NUM> degrees, the manufacturing by the electroforming method becomes difficult. Further, from both side surfaces located at the base end (the lower end in <FIG>) of the first contact part <NUM>, the retaining parts <NUM>, <NUM> respectively extend in the X1-X2 direction. As illustrated in <FIG>, the width dimension of each of the retaining parts <NUM>, <NUM> in the X1-X2 direction is smaller than an inner diameter of a first housing hole <NUM> of a housing cover <NUM>, described later, and is larger than an inner diameter of a first sliding hole <NUM>. It is sufficient that the contact surface of at least one of the first contact <NUM> and the second contact <NUM> is inclined so as to descend along the thickness direction. Although the first contact <NUM> is described here, the contact surface of the second contact <NUM> may be made inclined so as to descend along the thickness direction.

As illustrated in <FIG>, the second plunger <NUM> has a flat plate shape extending along the Z1-Z2 direction and is formed to have mostly the same thickness dimension. The second plunger <NUM> is made up of a second contact part <NUM> and the first and second elastic pieces <NUM>, <NUM> extending from the base end (the upper end in <FIG>) of the second contact part <NUM> in the Z1 direction. A surface along the Y1-Y2 direction of the second plunger <NUM> is defined as a main surface, and a surface along the X1-X2 direction orthogonal to the main surface is defined as a side surface.

The second contact part <NUM> has a flat plate shape having a substantially rectangular cross section, and the second contact <NUM> having a V shape as seen from the main surface is provided at the tip (the lower end in <FIG>) of the second contact part <NUM>. Further, from both side surfaces located at the base end (the upper end in <FIG>) of the second contact part <NUM>, the retaining parts <NUM>, <NUM> respectively protrude in the Y1-Y2 direction. As illustrated in <FIG>, similarly to the retaining parts <NUM>, <NUM> described above, the width dimension of each of the retaining parts <NUM>, <NUM> in the Y1-Y2 direction is smaller than an inner diameter of a second housing hole <NUM> of a housing body <NUM> described later, and is larger than an inner diameter of a second sliding hole <NUM>.

The first and second elastic pieces <NUM>, <NUM> extend from the base end of the second contact part <NUM> in parallel at a predetermined interval therebetween and along the Z1 direction. Further, the first and second elastic pieces <NUM>, <NUM> extend from both side edges of the base end of the second contact part <NUM> so as to have a gap larger than the thickness dimension (Y1-Y2 direction) of the first plunger <NUM>.

The distance between the outer surfaces of the first and second elastic pieces <NUM>, <NUM>, namely, the distance in the Y1-Y2 direction is substantially equal to the width dimension of the second contact part <NUM> in the Y1-Y2 direction. The distance between the opposed inner surfaces of the first and second elastic pieces <NUM>, <NUM> is larger than the thickness dimension (Y1-Y2 direction) of the first plunger <NUM>. The first elastic piece <NUM> is longer than the second elastic piece <NUM>.

Moreover, a contact protrusion <NUM> protrudes toward the Y2 direction at the tip of the inner surface of the first elastic piece <NUM>. A guide protrusion <NUM> protrudes toward the Y1 direction at the tip of the inner surface of the second elastic piece <NUM>. The probe pin is formed such that, when the guide protrusion <NUM> of the second elastic piece <NUM> is fitted into the guide groove <NUM> of the first plunger <NUM>, the contact protrusion <NUM> always comes into contact with the main surface of the clamped part <NUM> of the first plunger <NUM>.

Next, a process of assembling an inspection unit <NUM> provided with the probe pin <NUM> of the first comparative example not claimed will be described. The inspection unit <NUM> is an example of an electronic device.

First, the probe pin <NUM> is assembled. First, as illustrated in <FIG>, the clamped part <NUM> of the first plunger <NUM> is inserted from the upper end side of the coil spring <NUM> in the Z1 direction. Then, the first and second elastic pieces <NUM>, <NUM> of the second plunger <NUM> are inserted from the lower end side of the coil spring <NUM> in the Z2 direction. At this time, as illustrated in <FIG>, the first and second plungers <NUM>, <NUM> are assembled such that the main surface of the first plunger <NUM> and the main surface of the second plunger <NUM> are orthogonal to each other.

When the first and second plungers <NUM>, <NUM> are inserted deeply into the coil spring <NUM>, the clamped part <NUM> of the first plunger <NUM> is inserted between the first and second elastic pieces <NUM>, <NUM> of the second plunger <NUM>. Hence, the clamped part <NUM> is sandwiched between the first elastic piece <NUM> and the second elastic piece <NUM>. Further, when the first and second plungers <NUM>, <NUM> are inserted deeply into the coil spring <NUM>, the guide protrusion <NUM> of the second plunger <NUM> is fitted into the guide groove <NUM> of the first plunger <NUM>, to connect the first and second plungers <NUM>, <NUM>. As a result, the assembly of the probe pin <NUM> having the configuration in which the first and second plungers <NUM>, <NUM> are coupled to each other so as to be slidable in the coil spring <NUM> is completed. At this time, the contact protrusion <NUM> of the second elastic piece <NUM> of the second plunger <NUM> is constantly in contact with the main surface located above the guide groove <NUM>, illustrated in <FIG>, out of the main surface of the clamped part <NUM> of the first plunger <NUM>.

Next, as illustrated in <FIG>, <NUM>(A) and <NUM>(B), the assembled probe pin <NUM> is assembled into the insulative housing of the inspection unit <NUM>. That is, the second plunger <NUM> is inserted into the second housing hole <NUM> provided in the insulating housing body <NUM> constituting the housing. Then, after the second contact part <NUM> and the first and second elastic pieces <NUM>, <NUM> of the second plunger <NUM> are respectively housed into the second sliding hole <NUM> and the second housing hole <NUM> of the housing body <NUM>, the housing body <NUM> is covered with an insulating housing cover <NUM>. As a result, the clamped part <NUM> and the first contact part <NUM> of the first plunger <NUM> are respectively housed into the first housing hole <NUM> and the first sliding hole <NUM> of the housing cover <NUM>, and the assembling work of the inspection unit <NUM> is completed.

As illustrated in <FIG>, in the inspection unit <NUM>, the assembling work of which has completed, the retaining part <NUM> of the first plunger <NUM> is engaged with the inner opening edge of the first sliding hole <NUM> of the housing cover <NUM>. Similarly, the retaining part <NUM> of the second plunger <NUM> is engaged with the inner opening edge of the second sliding hole <NUM> of the housing body <NUM>. Then, the coil spring <NUM> is compressed by the retaining part <NUM> and the retaining part <NUM>. Further, the first contact part <NUM> of the first plunger <NUM> protrudes from the first sliding hole <NUM> of the housing cover <NUM>. Similarly, the second contact part <NUM> of the second plunger <NUM> protrudes from the second sliding hole <NUM> of the housing body <NUM>.

When the inspection unit <NUM> having a large number of probe pins <NUM> is to be assembled, the same assembling work as described above may be repeated.

Next, the operation of the probe pin <NUM> assembled in the inspection unit <NUM> will be described.

First, the second contact part <NUM> of the inspection unit <NUM> is positioned above a printed wiring board <NUM>, and the inspection unit <NUM> is lowered. Thereby, the second contact <NUM> of the second contact part <NUM> is pressed against a connection pad <NUM> of the printed wiring board <NUM>. Hence, the coil spring <NUM> is further compressed through the retaining part <NUM> of the second plunger <NUM>.

Then, an inspection object <NUM> is positioned above the inspection unit <NUM>, and the inspection object <NUM> is lowered. Thereby, a ball solder <NUM> of the inspection object <NUM> is pressed against the first contact <NUM>, having the V shaped cross section, of the first plunger <NUM>. Hence, the retaining part <NUM> of the first plunger <NUM> pushes down and compresses the coil spring <NUM>. As a result, the clamped part <NUM> of the first plunger <NUM> descends and the guide protrusion <NUM> of the second plunger <NUM> slides in the guide groove <NUM> of the first plunger <NUM>. At the same time, the contact protrusion <NUM> of the second plunger <NUM> slides on the main surface of the clamped part <NUM> of the first plunger and is electrically connected. It is thereby possible to inspect whether or not the inspection object <NUM> normally operates.

According to the comparative example, as illustrated in <FIG>, the contact surface of the first contact <NUM> is inclined so as to descend in the Y2 direction. Therefore, the ball solder <NUM> slides along the wiping surface which is the contact surface descending in the Y2 direction, and the oxide film of the ball solder <NUM> is scraped off on the contact surface of the first contact <NUM>. As a result, contact failure does not occur and variation in inspection accuracy does not occur.

Particularly, when the ball solder <NUM> comes into partial contact with the first contact <NUM>, the ball solder <NUM> is also scraped along the V shaped inclined surface of the first contact <NUM>. Thus, since the oxide film of the ball solder <NUM> is more reliably scraped off, contact failure is less likely to occur and the inspection accuracy is improved.

Further, since the contact surface of the first contact <NUM> has a V shape, there is an advantage that the ball solder <NUM> hardly falls off when the ball solder <NUM> comes into contact with the contact surface of the first contact <NUM>.

Finally, when the inspection object <NUM> is pulled up and the ball solder <NUM> is released from the first contact <NUM>, the retaining part <NUM> of the first plunger <NUM> is pushed up by the spring force of the coil spring <NUM>. Then, the retaining part <NUM> of the first plunger <NUM> is engaged with the inner edge of the first sliding hole <NUM> of the housing cover <NUM>, and returns to the initial state. Thereafter, repeating a similar operation enables inspection of the inspection object <NUM>.

When the guide protrusion <NUM> of the second plunger <NUM> is fitted in the guide groove <NUM> of the first plunger <NUM>, the contact protrusion <NUM> of the second elastic piece <NUM> is constantly pressed against the main surface of the clamped part <NUM> of the first plunger <NUM>. Hence, it is possible to ensure high contact stability between the first and second plungers <NUM>, <NUM>.

The relative sliding movement of the first and second plungers <NUM>, <NUM> is performed by the guide protrusion <NUM> of the second plunger <NUM> being engaged with the guide groove <NUM> of the first plunger <NUM>. There is thus no variation in the contact position between the clamped part <NUM> of the first plunger <NUM> and the contact protrusion <NUM> of the second plunger <NUM>, and an inspection unit having no variation in inspection accuracy can be obtained.

In the first comparative example not claimed, as illustrated in <FIG>, as another example of the elastic part, the elastic part may be made up of a bellows-shaped elastic body <NUM> in place of the coil spring <NUM>, and may have a form in which a first contact part <NUM> provided with the first contact <NUM> and a second contact part <NUM> provided with the second contact <NUM> are integrally molded so as to be mutually reciprocable via the elastic body <NUM>. With such a configuration, the structure can be simplified.

As illustrated in <FIG>, a probe pin according to a second comparative example not claimed is mostly the same as the above first comparative example not claimed, and the difference from the first comparative example not claimed is that a peeling projection <NUM> having a triangular cross section is provided in the center of the V shaped first contact <NUM> along the thickness direction. Since the others are similar to those in the above first comparative example not claimed, the same portions are provided with the same numerals, and descriptions thereof are omitted.

According to the comparative example, since the peeling projection <NUM> can more reliably peel off the oxide film of the ball solder, there is an advantage that the inspection accuracy is improved.

As illustrated in <FIG>, a probe pin according to a third comparative example not claimed is mostly the same as the above first comparative example not claimed except that the contact surface of the first contact <NUM> is inclined so as to descend in the X2 direction and is made a flat surface. Furthermore, the contact surface of the first contact <NUM> is inclined so as to also descend in the Y2 direction.

According to the comparative example, when the ball solder comes into contact with the contact surface of the first contact <NUM>, the ball solder slides along the diagonal line of the contact surface of the first contact <NUM> and is scraped. Therefore, even when the cross-sectional area of the contact surface of the first contact part <NUM> is small, the ball solder slides a long distance. As a result, the oxide film of the ball solder can be reliably scraped off, and there is thus an advantage that it is possible to obtain a probe pin in which contact failure hardly occurs.

As illustrated in <FIG>, a probe pin according to a first embodiment is mostly the same as the above third comparative example not claimed except that an engagement projection <NUM> is provided on the X2 side edge of the contact surface of the first contact <NUM>. As in the third comparative example not claimed, the contact surface of the first contact <NUM> is inclined so as to descend in the Y2 direction as well.

According to the embodiment, when a ball solder (not shown) comes into contact with the contact surface of the first contact <NUM>, the oxide film of the ball solder is scraped along the contact surface of the first contact <NUM> and an oxide film is peeled off. It is thus possible to obtain a probe pin in which contact failure hardly occurs. In addition, since the ball solder is engaged with the engagement projection <NUM>, there is an advantage that the ball solder hardly falls off.

As illustrated in <FIG>, a probe pin according to a second embodiment is mostly the same as the above first embodiment except that the peeling projection <NUM> having a triangular cross section is provided at the base part of the engagement projection <NUM> of the first contact <NUM> in the thickness direction. In addition, the contact surface of the first contact <NUM> is inclined so as to descend in the Y2 direction.

According to the embodiment, there is an advantage that the oxide film of the ball solder is more reliably scraped off by the peeling projection <NUM>, and contact failure hardly occurs.

As illustrated in <FIG>, a probe pin according to a fourth comparative example not claimed is mostly the same as the above first comparative example not claimed except that the first contact <NUM> has a flat contact surface along the X1 direction and the X2 direction. Further, as illustrated in <FIG>, the contact surface of the first contact <NUM> is inclined so as to descend in the Y2 direction.

According to the comparative example, since the shape of the first contact <NUM> is simple, there is an advantage that the probe pin <NUM> with the first plunger <NUM> easy to manufacture can be obtained.

As illustrated in <FIG>, a probe pin according to a third embodiment is mostly the same as the above fourth comparative example not claimed except that the engagement projection <NUM> having a triangular cross section is provided at the edge in the X2 direction side of the contact surface of the first contact <NUM> in the thickness direction (Y1-Y2 direction). As in the fourth comparative example not claimed, the contact surface of the first contact <NUM> is inclined so as to descend in the Y2 direction, as illustrated in <FIG>.

According to the embodiment, the ball solder slides on the contact surface of the first contact <NUM> which is inclined so as to descend in the Y2 direction, and the oxide film of the ball solder is scraped off. Hence, a probe pin free from contact failure can be obtained. Further, since the ball solder is engaged with the engagement projection <NUM>, there is an advantage that the ball solder hardly falls off.

As illustrated in <FIG>, a probe pin according to a fourth embodiment is mostly the same as the above fourth comparative example not claimed except that peeling grooves <NUM>, <NUM> are provided at both side edges of the contact surface of the first contact <NUM> in parallel along the Y2 direction. As in the fourth comparative example not claimed, the contact surface of the first contact <NUM> is inclined so as to descend in the Y2 direction, as illustrated in <FIG>.

According to the embodiment, the oxide film of the ball solder is scraped off by the peeling grooves <NUM>, <NUM> provided along the Y1-Y2 direction. Hence, a probe pin free from contact failure can be obtained. In addition, since the ball solder is likely to be caught in the peeling groove <NUM>, the ball solder hardly falls off.

As illustrated in <FIG>, a probe pin according to a fifth comparative example not claimed is mostly the same as the above fourth comparative example not claimed except that a recess <NUM> is formed at the corner in the X2 direction and the Y2 direction of the contact surface of the first contact <NUM>. As in the fourth comparative example not claimed, the contact surface of the first contact <NUM> is inclined so as to descend in the Y2 direction, as illustrated in <FIG>.

According to the comparative example, since the oxide film of the ball solder is scraped off in the recess <NUM> of the first contact <NUM>, a probe pin free from contact failure can be obtained. The contact reliability is improved. In addition, since the ball solder is likely to be caught in the peeling groove <NUM>, the ball solder hardly falls off.

As illustrated in <FIG>, a probe pin according to a sixth comparative example not claimed is mostly the same as the above fourth comparative example not claimed except that the contact surface of the first contact <NUM> is an arcuate surface. Further, as illustrated in <FIG>, the first contact <NUM> is inclined so as to descend in the Y2 direction.

According to the comparative example, the ball solder slides on the contact surface of the first contact <NUM> and the oxide film of the ball solder is scraped off, so that a probe pin free from contact failure can be obtained. In particular, since the contact surface of the first contact <NUM> has an arcuate surface, the contact area is large and contact reliability is further improved. In addition, since the first contact <NUM> is an arcuate surface, there is an advantage that a probe pin with which the ball solder hardly falls off can be obtained.

According to the various aspects of the present invention, when the ball solder comes into contact with the inclined contact surface of the probe pin, the ball solder is scraped at the contact surface and the oxide film of the ball solder is scraped off. Therefore, contact failure is less likely to occur, and there is an effect that an electronic device with uniform inspection accuracy can be obtained.

Note that by appropriately combining freely selected embodiments or modifications of the above variety of embodiments and modifications, it is possible to achieve the respective effects of those combined. While it is possible to combine embodiments, combine examples, or combine an embodiment and an example, it is also possible to combine features in different embodiments or examples.

While the present invention has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, a variety of modifications or corrections will be apparent to those skilled in the art. Such modifications or corrections are to be understood as being included in the scope of the invention according to the appended claims so long as not deviating therefrom.

Claim 1:
A probe pin (<NUM>), comprising:
an elastic part (<NUM>) extending and contracting along a center line in an extending direction;
a first plate shaped plunger (<NUM>);
a second plate shaped plunger (<NUM>);
the first plunger (<NUM>) comprising a first contact (<NUM>) disposed on one side of the probe pin (<NUM>) in the direction of the center line and having a rectangular cross section; and
the second plunger (<NUM>) comprising a second contact (<NUM>) disposed on another side of the probe pin (<NUM>) in the direction of the center line and having a rectangular cross section, wherein
the first contact (<NUM>) and the second contact (<NUM>) are supported so as to be reciprocable via the elastic part (<NUM>) and are electrically connected to each other,
the first contact (<NUM>) is an inclined surface which is disposed in an end face of the first contact (<NUM>) in the extending direction and inclined along the thickness direction of the first plunger (<NUM>), characterized in that
the first contact (<NUM>) has an asymmetrical V shape with respect to a center of the first contact (<NUM>) in the width direction of the first plunger (<NUM>), and
an engagement projection (<NUM>) is provided at one of end portions of the first contact (<NUM>) in the width direction of the first plunger (<NUM>), the one of the end portions having a tip that is closer to the second contact (<NUM>) in the extending direction than a tip of the other of the end portions, which engagement projection (<NUM>) can engage in the width direction of the first plunger (<NUM>) an inspection object (<NUM>) contacted by the first contact (<NUM>).