JPH0592749U - Through-hole resistance measurement probe - Google Patents

Abstract

(57) [Abstract] [Purpose] The printed wiring board has through holes for electricity. There is a method of measuring the resistance value of the through hole as a convenient method for checking the finish quality of the through hole. However, since a through hole usually has a minute resistance of about several hundred μΩ, it is necessary to perform the four-terminal measurement method. A convenient through-hole resistance measurement probe for performing this measurement method has a conical convex tip, which is convenient for applying to the measurement end of a through-hole. Since it is configured in an equal relationship with the terminals, the reference measurement current flowing in the through hole does not flow uniformly and becomes non-uniform, resulting in a measurement error. The purpose of the present invention is to eliminate this measurement error. [Structure] The entire outer portion of the conical convex shape of the tip of the resistance measuring probe is used as a current terminal 1, and the voltage terminal 2 is a pin-shaped conductor that coincides with the central axis of the cylindrical portion of the probe. Make electrical connection to the outer current terminal only at the apex.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention determines the electric resistance (simply referred to as resistance) value of a hole that penetrates an object, particularly a plate-like object, that is, a through hole, or a hole for electricity that is usually provided in a print plate (insulator), that is, a normal through hole. It relates to a stylus or probe for measuring.

[0002]

[Prior Art]

 One convenient method for inspecting the quality of finished conductive holes, that is, through holes, on a printed circuit board is to measure the resistance between both ends of the through holes.

The resistance value of an ordinary through hole is small, and in particular, the through hole for conduction of a printed wiring board for printed wiring is a very small resistance, usually on the order of several hundreds of μΩ. A 4-terminal measurement is required so that is not included in the measured value.

FIG. 5 shows the configuration of the tip portion of a conventional probe that allows the through-hole resistance to be measured with four terminals and can be easily measured, where 1 is a current terminal and 2 is a voltage terminal. Terminals 5 are insulating layers. (A) is a plan view and (b) is an elevation view. Then, FIG. 6 shows a state during the measurement. In this way, two probes are used, which are provided on the printed circuit board 3 and are pressed against the measurement end from both sides of the through hole 6 which is usually copper-plated 4, and is known from the constant current circuit between the two current terminals. Current, that is, the reference measurement current is passed. FIG. 7A shows an example of the distribution of the current flowing through the through hole from the current terminal contact line at this time.

In the case of the example shown in FIG. 7A, it is substantially equal to the voltage terminal contacting the portion of the current path closest to the voltage terminal contact line as shown by the arrow in FIG. 7A. However, the resistance inside the through hole is measured, which causes an error. (See (b) of FIG. 7) At this time, the resistance R of the through hole is calculated from the voltage V measured at the voltage terminal and the known current I from the equation R = V / I.

In the case of this conventional technique, depending on how the probe hits the measurement end of the through hole, the result may not be as shown in FIG. 7A, but in any case, the measurement is not performed by the conventional probe. For all the circumferences of the through hole, the current terminals contact at less than half of both measuring ends, that is, the contact can be made in close contact, that is, the known reference measurement current flowing for measurement is uniform in the through hole. It will not flow, which is a cause of error.

[0007]

[Problems to be solved by the device]

 In the conventional probe for measuring through-hole resistance, the conical convex portion at the tip has 50 and 50 current terminals and 50 voltage terminals as shown in FIG. Even though it is convenient, there is a problem that the reference measurement current is not caused by the through hole side but is caused by the probe side, which causes a measurement error because it does not flow uniformly through the through hole as described above. there were.

The present invention seeks to solve this problem. In other words, by improving the configuration of the probe side, the reference measurement current for measurement should be made to flow in the through hole as uniformly as possible and, if possible, to reduce this problem. It is the purpose of the present invention to try to solve it.

[0009]

[Means for Solving the Problems]

 In the present invention, the tip of a probe having a current terminal at the tip and a voltage terminal insulated from the tip is formed into a conical convex shape for measuring the resistance of a through hole. Up to this point, the idea is the same as in the prior art, but in the present invention, the current terminal and the voltage terminal are not equal, and the voltage terminal is made smaller and the probe tip is divided into four or eight as shown in FIG. Insulation is performed between both terminals by dividing so that it can be easily processed along the generatrix of the cone that passes through the apex of the cone. In this case, the smaller of the divided parts is the voltage terminal, and the larger part or the one with the larger number of divisions is the current terminal.

In another aspect of the present invention, the tip of the probe is formed into a conical convex shape as in the conventional case, but the entire outer circumference of the conical convex shape is used as a current terminal. The voltage terminal is electrically connected to the current terminal on the outer side in the vicinity of the inner vertex of the conical convex shape. Then, except for the tip of the probe, it is formed in a cylindrical shape. It is necessary to configure so that the current-carrying path conducted to the voltage terminal provided inside the cylindrical shape does not make electrical contact with the cylindrical shape.

[0011]

[Action]

 In the present invention, the outer shape of the conventional measuring probe is not changed, and the current terminal portion is larger than the conventional one. In another aspect of the present invention described above, all the probes that hit the measurement end of the through hole are current terminals.

The fact that the current terminal portion is large means that when the probe comes into contact with the measurement end of the through hole to be measured, the portion in contact with the current terminal of the probe or the measurement end of the through hole is large. The reference measurement current flows almost uniformly within the area, reducing the measurement error. For this reason, the voltage terminal section should be as small as possible.

Further, according to another aspect of the present invention, when the probe contacts the measurement end of the through hole, all the probes at the contact part are current terminals, so that the reference measurement current flows uniformly in the through hole. Therefore, the measurement error due to the non-uniformity of the reference measurement current flowing in the through hole can be eliminated.

[0014]

Embodiments For ease of understanding, an embodiment which is another aspect of the present invention will be described.

FIG. 1 is a plan view (a) showing a tip portion of a probe of the embodiment and an elevation view (b) mainly showing a tip portion of the probe. This cylindrical probe is made hollow, and one conductor is connected along the central axis of the inner part at the apex of the outer conductor having a conical convex shape only at its tip to form a pin shape. The pin-shaped conductor is the voltage terminal 2, and the outer cylindrical conductor is the current terminal 1 including the tip. In this example, since the voltage terminal and the current terminal are electrically connected at the apex of the cone, which is the tip of the cylinder, care must be taken when handling during non-measurement. The reference measurement current flows evenly through the through-hole when it comes into close contact with the measurement end, and the voltage detection end also becomes the contact surface between the probe and the through-hole, allowing measurement without error.

FIG. 2 is a sectional view of the through hole, showing how the reference measurement current flows uniformly through the copper plating 4 in the through hole provided in the printed board 3. Of course, when actually measuring as shown in FIG. 2, it is necessary to use two probes of the present invention (two as the Hi terminal and the Lo terminal) so that the total four terminals can be measured.

As another embodiment, examples of those shown in FIG. 3 and FIG. 4 will be described. The one shown in Fig. 3 has the same overall shape as the conventional one, and the tip of the cylindrical probe is made to be a conical convex shape. The voltage terminal is made smaller.

As shown in FIG. 3 (a), in the plane projection plane showing the tip of the probe, the rotation region portion of the plane projection angle of about 270 ° from the center point showing the apex is the tip of the current terminal 1. Is represented. With the exception of the insulating layer 5 made of a thin insulator, a fan-shaped portion having a rotation angle of about 90 ° from the center in a plane projection angle, that is, a rotation region represents the tip of the voltage terminal 2.

As described above, the fact that the current terminal portion is large means that the surface to which the current terminal contacts when the probe is in close contact with the through hole to be measured is large, so that the reference measurement flowing in the through hole is almost uniform. It means that the flow rate becomes larger and the measurement error becomes smaller accordingly. This means that the central angle of the fan shape at the tip of the voltage terminal 2, that is, the rotation angle, should be as small as possible.

If it is made too small, manufacturing difficulty will occur, but as shown in FIG. 4, it is divided into 4 or 8 along the line passing through the apex of the tip, and one of them is subjected to insulation processing as shown in the figure. And all others may be current terminals. In the case of the figure, there are 4 divisions and 8 divisions, but it is better to increase the number of divisions as long as there is no difficulty in manufacturing and to use more current terminals. It may be one or more. However, the measurement error decreases as the number of current terminals increases.

[0021]

[Effect of the device]

 INDUSTRIAL APPLICABILITY The present invention is suitable for measuring the resistance of a through hole, especially a low resistance through hole by four-terminal measurement. The body of the probe is cylindrical and its tip is formed in a conical convex shape, and it is formed symmetrically around its apex.Therefore, even if the probe is slightly tilted, the size of the through hole hole It becomes possible to measure without any. Moreover, if two probes configured as in the present proposal are used and the resistance is measured by the 4-terminal measurement technique, the reference measurement current for measurement is more uniform in the through-hole than the conventional one. Since the current flows close to or completely uniform, the measurement error caused by the nonuniform flow of the reference measurement current can be reduced or eliminated altogether.

[Brief description of drawings]

FIG. 1 is a diagram showing a probe according to an embodiment of the present invention. (A) is its plan view (b) is its elevation view

FIG. 2 is a diagram showing how a reference measurement current flows in a through hole when performing measurement with the probe of FIG.

FIG. 3 is a view showing a probe according to another embodiment of the present invention. (A) is its plan view (b) is its elevation view

FIG. 4 is a view showing a tip of a probe of a modified example of another embodiment of the present invention. (A) A plan view showing the tip of the probe divided into four (b) A plan view showing the tip of the probe divided into eight.

FIG. 5 is a diagram showing a probe according to a conventional technique. (A) A plan view thereof (b) An elevation view thereof

FIG. 6 is a partial cross-sectional view showing a mode in which a probe is brought into close contact with a through hole when performing measurement by a conventional technique.

FIG. 7 is a diagram showing a distribution of a reference measurement current in a through hole at the time of measurement by a conventional technique and an equivalent circuit at the time of measurement. (A) Diagram showing the distribution of the reference measurement current (b) Equivalent circuit diagram at the time of measurement

[Explanation of symbols]

 1 Current terminal 2 Voltage terminal 3 Printed board 4 Copper plating 5 Insulation layer 6 Through hole

Claims (4)

[Scope of utility model registration request] 1. For measuring the resistance of a through hole,
A probe having a current terminal and a voltage terminal insulated from this at the tip, and forming the tip into a conical convex shape,
At least 180 as a plane projection angle with respect to the entire rotation region of the generatrix extending from the apex of the cone on the outer side of the conical convex tip that contacts the measured portion and that forms the conical convex shape around the apex. Corresponding to all rotations over 3
A probe for measuring through-hole resistance, characterized in that most of the rotation angle region of less than 60 ° is a current terminal region and the remaining rotation angle region is a voltage terminal region. 2. The current terminal area according to claim 1, wherein the continuous 3/4 or 7/8 of all rotation angles is substantially the area and the rest is substantially the voltage terminal area. Through-hole resistance measurement probe. 3. A probe for measuring the resistance of a through hole, the tip of which is formed into a conical convex shape, and the entire circumference of the outer side of the conical convex tip that contacts the measured portion. Is a current terminal, and the voltage terminal is electrically connected from the inside to the outside current terminal only near the apex of the inner side of the conical convex shape. probe. 4. Except for the tip end portion of claim 3, the tip end portion is formed into a cylindrical shape, and this cylindrical portion serves as an electrical conduction path to be guided to a current terminal of the tip end portion, and the inside thereof is insulated from the cylindrical portion. A probe for measuring a through-hole resistance, characterized in that a conducting wire electrically connected to a voltage terminal is provided in parallel with the bus bar of the cylinder.