Contact detection mechanism for high frequency probe

Abstract

To accurately detect the push-in amount of a probe to a measuring pad.SOLUTION: This detecting mechanism 20 is supported movably in the vertical direction Z of the surface of a substrate 41, is provided with a tip part 11 projected to be inclined to the surface, and detects the position in the direction Z when the tip part 51a is brought into contact with the pad 11a in the high-frequency probe 1 provided with the tip part 11a brought into contact with the measuring pad 51a of the line to be measured on the tip side of the part 11. The sensor dog 2 is disposed on the side of the probe 1 opposite to the wired circuit substrate with the dog tip in contact with the side of the portion 11 opposite to the wired circuit substrate in the direction Z, the movable support portion 3 supports the dog 2 so as to be movable substantially in the direction Z with respect to the probe 1, the biasing portion 3a biases the support portion 3 so that the dog tip of the dog 2 comes into contact with the portion 11, and the sensor portion 4 detects the relative movement of the dog 2 driven via the dog tip with respect to the probe 1 according to the deflection of the portion 11 generated when the tip portion 51a comes into contact with the pad 11a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a contact detection mechanism for a high frequency probe, which detects the position at which a high frequency probe for testing the characteristic impedance of a printed circuit board comes into contact with a measurement pad. [Background technology]

[0002] An example of background art is the electrical characteristic testing device described in Patent Document 1. This electrical characteristic testing device aims to provide an electrical characteristic testing device for guaranteeing the characteristic impedance of a wiring circuit board such as a semiconductor package that includes a high-speed signal line on which a semiconductor element is mounted, and is composed of a high-frequency probe 110, a contact sensor 120, and a high-frequency probe fixing component 131. The contact sensor 120 detects the contact position between the high-frequency probe 110 and a measurement pad 151a of the line under test (SIGNAL) 151, and measures the characteristic impedance while maintaining a constant contact pressure between the high-frequency probe 110 and the measurement pad 151a of the line under test (SIGNAL) 151, thereby guaranteeing the characteristic impedance of the wiring circuit board such as a semiconductor package that includes a high-speed signal line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-292339 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the electrical characteristic testing device of Patent Document 1, as shown in FIG. 9, the contact position between the high-frequency probe 110 and the measurement pad 151a of the measured line 151 is indirectly detected based on the sensor signal of the contact sensor 120 that is arranged to contact the substrate 141 at a position away from the contact point of the high-frequency probe 110 with the substrate 141.

[0005] Therefore, if the contact sensor 120 is located outside the substrate because the measurement pad 151a is located near the edge of the substrate, there is a problem that the contact sensor 120 cannot detect that the high-frequency probe 110 has come into contact with the measurement pad 151a.

[0006] Furthermore, when the measurement pad 151a is located near the center of the board rather than near the edge, the contact sensor 120 can detect that the high-frequency probe 110 has come into contact with the measurement pad 151a. However, it is not easy to determine whether the contact sensor 120 is located on the SR (solder resist) 161. If the contact sensor 120 is located in a position where the SR 161 is not present (above the SR opening), the measurement is performed with the contact sensor 120 depressed 25 μm, which is the thickness of the SR 161. However, if the contact sensor 120 is located on the SR 161 and the thickness of the SR 161 varies and is 20 μm, the measurement is performed with the high-frequency probe 110 depressed 5 μm. This inconsistent depression of the high-frequency probe 110 results in an inconsistent contact pressure between the high-frequency probe 110 and the SR 161, which may result in unstable measurement values. Conversely, if a via (hole) or the like is located at the position of the contact sensor 120, the high-frequency probe 110 may be depressed too far, potentially damaging the high-frequency probe 110 in the worst case scenario. That is, the electrical characteristic inspection device of Patent Document 1 has a problem in that the amount of pressing of the high-frequency probe 110 depends on the surface state of the substrate 141 at the position of the contact sensor 120, and the amount of pressing is not constant.

[0007] Furthermore, if we consider the case where the inspection device is equipped with a component that serves as a height reference, there will be no interference if the measurement pad 151a is located near the edge of the board, but if the measurement pad 151a is located near the center of the board, there is a risk that the component that serves as the height reference will interfere with the board 141 (SR161 on the board), which also poses the problem of not being able to detect the height accurately. [Means for solving the problem]

[0008] In order to solve the above problems, the contact detection mechanism for a high frequency probe of the present invention comprises: A high-frequency probe is supported so as to be movable relative to a surface of a wiring circuit board on which a line to be measured exists in a vertical direction, and has a tip portion that protrudes at an angle toward the surface, and has a probe tip portion on the tip side of the tip portion that comes into contact with a measurement pad of the line to be measured. A contact detection mechanism for a high-frequency probe detects the position in the vertical direction when the probe tip portion comes into contact with the measurement pad, a sensor dog disposed on the opposite side of the high frequency probe to the wired circuit board, with the dog tip abutting against the opposite side of the wired circuit board in the vertical direction of the tip portion; a movable support portion that supports the sensor dog so that the sensor dog can move back and forth in the substantially vertical direction relative to the high-frequency probe; a biasing portion that biases the movable support portion so that the tip of the sensor dog contacts the tip portion; a sensor unit that detects relative movement of the sensor dog with respect to the high-frequency probe, the sensor dog being driven via the dog tip in response to bending of the tip portion that occurs when the probe tip contacts the measurement pad; It is equipped with:

[0009] According to this configuration, the amount of pressing of the tip portion of the high-frequency probe into the measurement pad is detected by detecting the amount of bending of the tip portion when the tip portion is brought into contact with the measurement pad, and the amount of pressing can be detected accurately and stably. This is realized by the electrical characteristic testing device of the present invention being configured to directly detect the contact between the high-frequency probe and the measurement pad, unlike the electrical characteristic testing device of the background art which is configured to indirectly detect the contact between the high-frequency probe and the measurement pad based on a sensor signal of a contact sensor that may come into contact with a portion of the wired circuit board other than the measurement pad. Furthermore, since the sensor dog is disposed on the side of the high-frequency probe opposite the wired circuit board, when the high-frequency probe is moved parallel to the surface of the wired circuit board, the sensor dog does not interfere with parts or members provided on the surface of the wired circuit board.

[0010] The sensor dog has a tip end that abuts against the approximate center of the tip end portion in the protruding direction.

[0011] According to this configuration, the contact detection mechanism for the high-frequency probe according to the present invention (the sensor dog) is not present on the tip side of the tip portion, so the probe tips of the multiple high-frequency probes can be brought close to each other as needed.

[0012] The movable support portion and the biasing portion are not particularly limited, but the following embodiments are given as examples. (1) The movable support unit includes a pair of links arranged parallel to each other at a distance from each other in the substantially vertical direction, the base ends of the pair of links are supported on the high-frequency probe side, and the sensor dog is supported on the tip ends of the pair of links, and each of the links is flexible enough to bend in the substantially vertical direction, either entirely or at both ends. In addition to this aspect, the biasing unit has an aspect in which the flexible portion has elasticity for biasing. (2) The movable support unit includes a pair of links arranged parallel to each other at a distance from each other in the substantially vertical direction, the base ends of the pair of links are supported on the high-frequency probe side, the sensor dog is supported on the tip ends of the pair of links, and both ends of each link are supported rotatably via shafts extending substantially parallel to the surface. In addition to this aspect, the biasing unit includes biasing means for biasing at least one of the links in the substantially vertical direction. (3) The movable support unit includes a rotating piece whose proximal end is supported on the high-frequency probe side via a rotating shaft extending substantially parallel to the surface, and whose distal end is rotatable in substantially the vertical direction, and the sensor dog is supported on the distal end of the rotating piece. In addition to this aspect, the biasing unit includes biasing means for biasing the rotating piece in the substantially vertical direction. [Effects of the Invention]

[0013] The contact detection mechanism for a high-frequency probe according to the present invention has the excellent effect of being able to accurately and stably detect the amount of pressing of a high-frequency probe into a measurement pad of a line to be measured on a printed circuit board. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a side view of a printed circuit board inspection device equipped with a contact detection mechanism for a high-frequency probe according to a first embodiment of the present invention; [Figure 2] FIG. 2 is a plan view of the wired circuit board inspection device. [Figure 3] FIG. 2 is a perspective view of the wired circuit board inspection device. [Figure 4] FIG. 2 is a side cross-sectional view showing the configuration of a sensor unit of the wired circuit board inspection device. [Figure 5] 10 is a graph showing the relationship between the amount of movement of the high-frequency probe in the Z-axis direction and the sensor value of the sensor unit. [Figure 6] FIG. 10 is a side view of a printed circuit board inspection device equipped with a contact detection mechanism for a high-frequency probe according to a second embodiment of the present invention. [Figure 7] FIG. 2 is a plan view of the wired circuit board inspection device. [Figure 8] FIG. 2 is a perspective view of the wired circuit board inspection device. [Figure 9] FIG. 1 is a schematic diagram showing an example of an electrical characteristic inspection device according to the background art; DETAILED DESCRIPTION OF THE INVENTION

[0015] 1 to 5 show a wired circuit board inspection device 30 equipped with a high-frequency probe contact detection mechanism 20 of a first embodiment. As shown in Fig. 1 to 3, this wired circuit board inspection device 30 includes a high-frequency probe 1 that is brought into contact with a measurement pad 51a of a line to be measured 51 on a wired circuit board 41, a high-frequency probe contact detection mechanism 20 that is attached to the high-frequency probe 1, and a relative movement mechanism (not shown) that moves the high-frequency probe 1 and the high-frequency probe contact detection mechanism 20 relative to the surface of the wired circuit board 41 on which the line to be measured 51 exists.

[0016] The high-frequency probe 1 has a tip portion 11 that protrudes at an angle toward the surface of the wired circuit board 41 on which the line under test 51 is located. The tip portion 11 has a probe tip portion 11a at its tip end that comes into contact with a measurement pad 51a of the line under test 51, and a semi-rigid portion 11b that supports the base end of the probe tip portion 11a.

[0017] The relative movement mechanism includes a Z-direction movement mechanism for moving in the Z direction, which is the direction perpendicular to the surface of the wired circuit board, and an X-direction movement mechanism and a Y-direction movement mechanism for moving in the X-direction and Y-direction, which are perpendicular to each other on the same surface. The Z-direction movement mechanism in this example is a mechanism for bringing the high-frequency probe 1 into or out of contact with the measurement pad 51a of the line under test 51, and is composed of a servo motor, a SERVOPACK (registered trademark), etc.

[0018] The high-frequency probe contact detection mechanism 20 detects the position in the Z direction when the probe tip 11a contacts the measurement pad 51a, and includes a sensor dog 2, a movable support unit 3, a biasing unit 3a, and a sensor unit 4. The high-frequency probe 1 is connected to a measurement cable 5, the other end of which is connected to a measurement device (not shown) to perform the desired measurement (S-parameter (Scattering parameter) measurement, TDR (Time Domain Reflectometry) measurement, etc.). The high-frequency probe 1 is not particularly limited, but an ACP probe manufactured by FormFactor, Inc., or the like, can be used.

[0019] The sensor dog 2 is arranged on the opposite side of the wired circuit board of the high-frequency probe 1, with the dog tip abutting against the opposite side of the wired circuit board in the Z direction of the tip portion 11. In this example, the sensor dog 2 has its dog tip abutting against approximately the center in the protruding direction of the tip portion 11. In addition, the sensor dog 2 in this example is made of metal (stainless steel).

[0020] The movable support unit 3 is configured to support the sensor dog 2 so that it can move back and forth in approximately the Z direction relative to the high-frequency probe 1. In this example, the movable support unit 3 is provided on both sides of the base end of the sensor dog 2. The tip end of each movable support unit 3 is fixed to the sensor dog 2, and the base end is fixed to the support unit 7. The movable support unit 3 includes a pair of links arranged parallel to each other and spaced apart in approximately the vertical direction, the base ends of the pair of links are supported on the high-frequency probe side, and the sensor dog 2 is supported on the tip end side of the pair of links, and both ends of each link are flexible so that it can bend in the approximately vertical direction. In addition, the movable support unit 3 in this example is made of resin (PPS (polyphenylene sulfide) resin). Note that each link can be modified to have flexibility so that the entire link is flexible so that it can bend in the approximately vertical direction.

[0021] The biasing portion 3a is configured to bias the movable support portion 3 so that the tip of the sensor dog 2 contacts the tip portion 11. The biasing portion 3a of this example biases the sensor dog 2 substantially in the Z direction via the movable support portion 3. The biasing portion 3a of this example is configured so that the bendably flexible portion of the link has elasticity for biasing, and the biasing force is exerted by elastic deformation of this portion. Such a biasing portion 3a made of resin is not particularly limited, but an example will be shown in which it is used for the purpose of bringing the probe tip portion 11a into contact with the measurement pad 51a with weak pressure.

[0022] As shown in FIG. 4 , the sensor unit 4 is configured to detect the relative movement of the sensor dog 2, driven via the dog tip, with respect to the high-frequency probe 1 in response to the deflection of the tip portion 11 that occurs when the probe tip 11a contacts the measurement pad 51a. In this example, the sensor unit 4 is an optical sensor that detects the amount of received light that accompanies a change in the position of the sensor dog 2. It includes a light-emitting unit 4b that emits light and a light-receiving unit 4a that receives the light. The light from the light-emitting unit 4b is directed toward a slit 8a in a slit member 8 provided between the sensor dog 2 and the sensor dog 2. When the sensor dog 2 moves to a position overlapping the slit 8a, the light is reflected by the sensor dog 2. The light reflected by the sensor dog 2 is received by the light-receiving unit 4a via the slit 8a in the slit member 8. The amount of reflected light varies depending on the position of the sensor dog 2, and the amount of light incident on the light-receiving unit 4a varies accordingly. In this example, the greater the relative movement of the sensor dog 2 with respect to the high-frequency probe 1, the greater the area of ​​the sensor dog 2 that overlaps the slit hole 8a, thereby increasing the amount of light reflected and incident on the light-receiving unit 4a. As shown in FIG. 5 , the sensor unit 4 in this example is configured so that the sensor value decreases as the amount of light incident on the light-receiving unit 4a increases. The mounting position of the slit member 8 relative to the sensor dog 2 is adjustable in the Z direction. Adjusting this mounting position allows for adjustment of the amount of light incident on the light-receiving unit 4a, thereby enabling adjustment of the sensor value output by the sensor unit 4. Note that the measurement pad contact position (height in the Z direction) is determined in advance, and the sensor value at the desired displacement position (height in the Z direction) is confirmed. By stopping the movement in the Z direction when this sensor value is reached, it is possible to always perform measurements with the high-frequency probe 1 at the same displacement.

[0023] Next, the Z-axis operation of the high-frequency probe 1 in the wired circuit board inspection device 30 configured as above will be described.

[0024] As shown in the graph in Figure 5 which shows the relationship between the amount of movement of the high-frequency probe 1 and the sensor value of the sensor unit 4, the sensor value when not in contact with the measurement pad 51a of the measured line of the wiring circuit board 41 is a, and the sensor value when the measurement pad 51a of the measured line is contacted and then pressed by a set amount is b, and the sensor is set to be ON when the sensor value is b.

[0025] The sensor value is constant (a) until the high-frequency probe 1 comes into contact with the measurement pad 51a of the line under test 51, and once it comes into contact with the measurement pad 51a of the line under test 51, the sensor value begins to decrease. As the high-frequency probe 1 is moved (pushed in), the sensor turns ON when the sensor value reaches b, and the movement of the high-frequency probe 1 stops. (When the sensor value exceeds b, the sensor is OFF; when the sensor value is equal to or less than b, the sensor is ON.) The amount of change in the sensor value when moved by the pushing amount is (ab).

[0026] After the high-frequency probe 1 is moved to a position where the XY coordinates of the tip of the probe tip 11a coincide with the measurement pad 51a of the line under test, the high-frequency probe 1 starts to move in the Z direction (the direction approaching the wired circuit board 41). At this point, the positional relationship between the sensor dog 2 and the high-frequency probe 1 is always constant, and the sensor value is also constant (sensor value a in the case of the graph above).

[0027] When the high-frequency probe 1 is moved in the Z direction (toward the measurement pad 51a), the probe tip 11a eventually comes into contact with the measurement pad 51a. Up until this point, the positional relationship between the sensor dog 2 and the high-frequency probe 1 is always constant, and the sensor value is also constant (sensor value a in the above graph).

[0028] If the high-frequency probe 1 is further moved in the Z direction, the semi-rigid part 11b of the high-frequency probe 1 deforms, and the sensor dog 2 is pushed in the -Z direction. As the positional relationship between the sensor dog 2 and the high-frequency probe 1 changes, the sensor value also changes. In the graph above, the sensor value gradually decreases from a.

[0029] As the high-frequency probe 1 continues to move in the Z direction, the sensor value eventually reaches b. When the sensor value reaches b, the sensor is set to turn ON, so the high-frequency probe 1 stops moving in the Z direction. The desired measurement is then performed.

[0030] After the desired measurement is performed, the high-frequency probe 1 is moved in the −Z direction to move from the measurement pad 51a of the line under test to a non-contact position.

[0031] The high-frequency probe contact detection mechanism 20 of this embodiment configured as described above is configured to detect the amount of deformation of the tip portion 11 of the high-frequency probe 1 when the tip portion 11 is brought into contact with the measurement pad 51a, thereby detecting the amount of depression of the tip portion 11 into the measurement pad 51a, and can accurately and stably detect the amount of depression. This is achieved by directly detecting contact between the high-frequency probe 1 and the measurement pad 51a, unlike the electrical characteristic testing device of the background art, which is configured to indirectly detect contact between the high-frequency probe and the measurement pad based on a sensor signal from a contact sensor that may contact a portion of the wired circuit board 41 other than the measurement pad 51a. Furthermore, because the sensor dog 2 is located on the side of the high-frequency probe 1 away from the wired circuit board, the sensor dog 2 does not interfere with components or members provided on the surface of the wired circuit board 41 when the high-frequency probe 1 is moved parallel to the surface of the wired circuit board 41.

[0032] Furthermore, the sensor dog 2 has its dog tip abutting against approximately the center in the protruding direction of the tip portion 11. With this configuration, the configuration (sensor dog 2) of the high-frequency probe contact detection mechanism 20 according to the present invention is not present on the tip side of the tip portion 11, so the probe tips 11a of the multiple high-frequency probes 1 can be brought close to each other as needed.

[0033] 6 to 8 show a second embodiment of the present invention. This high-frequency probe contact detection mechanism 20 differs from the first embodiment mainly in the following points. Therefore, parts common to the first embodiment are designated by the same reference numerals and will not be described again.

[0034] In this example, instead of the movable support part 3, movable support parts 9 are provided on both sides of the base end part of the sensor dog 2. The tip side of each movable support part 9 is fixed to the sensor dog 2, and the base side is pivotally supported on the high-frequency probe side via a rotation shaft 9a extending approximately parallel to the surface of the wired circuit board 41. With this configuration, the movable support part 9 rotates back and forth around the rotation shaft 9a, supporting the sensor dog 2 so that it can move back and forth approximately in the Z-axis direction.

[0035] The biasing unit 10 of this embodiment includes a metal leaf spring 10a as a biasing means for biasing the movable support unit 9 in the substantially vertical direction. This metal leaf spring 10a is attached to the support unit 7, and the sensor dog 2 is attached to the opposite side of the support unit 7. When the movable support unit 9 rotates, it elastically deforms, biasing the movable support unit 9 so that the sensor dog 2 always abuts against the semi-rigid portion 11b of the high-frequency probe 1. When not biased by the metal leaf spring 10a, the movable support unit 9 is configured to rotate with almost no load. The biasing unit 3a of the first embodiment has a spring load of 8.1 gf when pressed 1 mm, while the metal leaf spring 10a of this embodiment is designed to have a spring load of 8.1 g / mm. The biasing unit 3a of the first embodiment is made of resin and moves substantially parallel in the Z direction by elastic deformation. Therefore, it is used to bring the probe tip 11a into contact with the measurement pad 51a with weak pressure. On the other hand, as will be described later, the metal plate spring 10a of the biasing portion 10 in this example is also used for the purpose of biasing the sensor dog 2 to always be in contact with the semi-rigid portion 11b of the high-frequency probe 1, because the movable support portion 9 rotates around its rotation axis 9a with almost no load, and has a different role from that of the biasing portion 3a in the first embodiment.

[0036] The Z-axis movement of the high-frequency probe 1 in the wired circuit board inspection device 30 of this example is the same as that in the first embodiment.

[0037] The high-frequency probe contact detection mechanism 20 of this embodiment configured as described above can also provide the same effects as those of the first embodiment.

[0038] The present invention is not limited to the above-described embodiment, and can be embodied by making appropriate modifications within the scope of the invention, for example, as follows. (1) The movable support unit is changed to a parallel link mechanism (having a pair of links arranged parallel to each other at a distance from each other in approximately the vertical direction, with the base ends of the pair of links supported on the high-frequency probe side and the sensor dog 2 supported on the tip ends of the pair of links, and each of the links being supported at both ends rotatably via an axis extending approximately parallel to the surface of the wired circuit board 41). In addition to this, the biasing unit is changed to a mode including biasing means for biasing at least one of the links in approximately the Z direction. (2) The sensor unit 4 may be changed to a non-contact sensor that detects changes in magnetic force, or to a contact sensor that detects physical contact. [Explanation of symbols]

[0039] 1 high frequency probe 2 Sensor Dog 3 Movable support part 3a Biasing part 4 Sensor section 4a Light receiving part 4b Light-emitting part 5 Measurement Cable 6 Sensor board 7 Support part 8 Slit member 8a Slit hole 9 Movable support part 9a Rotation axis 10. Actuation section 10a metal leaf spring 11 Tip part 11a Probe tip 11b Semi-rigid section 20 Contact detection mechanism for high frequency probe 30 Wiring circuit board inspection equipment 41 Wired circuit board 51 Line under test 51a Measuring Pad 61 SR (solder resist)

Claims

1. A high-frequency probe is supported so as to be movable relative to a surface of a wiring circuit board on which a line to be measured exists in a vertical direction, and has a tip portion that protrudes at an angle toward the surface, and has a probe tip portion on the tip side of the tip portion that comes into contact with a measurement pad of the line to be measured. A contact detection mechanism for a high-frequency probe detects the position in the vertical direction when the probe tip portion comes into contact with the measurement pad, a sensor dog disposed on the opposite side of the high frequency probe to the wired circuit board, with the dog tip abutting against the opposite side of the wired circuit board in the vertical direction of the tip portion; a movable support portion that supports the sensor dog so that the sensor dog can move back and forth in the substantially vertical direction relative to the high-frequency probe; a biasing portion that biases the movable support portion so that the tip of the sensor dog contacts the tip portion; a sensor unit that detects relative movement of the sensor dog with respect to the high-frequency probe, the sensor dog being driven via the dog tip in response to bending of the tip portion that occurs when the probe tip contacts the measurement pad; Equipped with Contact detection mechanism for high frequency probes.

2. 2. A contact detection mechanism for a high frequency probe according to claim 1, wherein the tip of said sensor dog is in contact with a substantially central portion of said tip portion in a protruding direction.

3. the movable support unit includes a pair of links that are provided parallel to each other at a distance from each other in the substantially vertical direction, the base ends of the pair of links being supported on the high-frequency probe side, and the sensor dog being supported on the tip ends of the pair of links, and each of the links is flexible enough to be bent in the substantially vertical direction, either entirely or at both ends thereof; The biasing portion has a flexible portion that is capable of being bent and has elasticity for biasing.

3. The contact detection mechanism for a high frequency probe according to claim 1.

4. the movable support unit includes a pair of links that are arranged parallel to each other and spaced apart in the substantially vertical direction, the base ends of the pair of links being supported on the high-frequency probe side, and the sensor dog being supported on the tip ends of the pair of links, and both ends of each of the links are supported rotatably via shafts that extend substantially parallel to the surface, The biasing portion includes a biasing means for biasing at least one of the links in the substantially vertical direction.

3. The contact detection mechanism for a high frequency probe according to claim 1.

5. the movable support unit includes a rotating piece whose base end is pivotally supported on the high-frequency probe side via a rotating shaft extending substantially parallel to the surface, and whose tip end is rotatable in substantially the vertical direction, and the sensor dog is supported on the tip end of the rotating piece, The biasing portion includes biasing means for biasing the rotating piece in the substantially vertical direction.

3. The contact detection mechanism for a high frequency probe according to claim 1.

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