JPS59222996A - Device for holding hanger in surface treating equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring the resistance of a plated portion of a plated through hole of a printed wiring board.

Methods for determining the plating thickness and plating quality of through-hole plating areas include cross-sectional methods using a microscope and methods using a beta reflection type measuring device. By the way, the former method requires a lot of time and effort to prepare the test piece because it requires removal of νJ from the through-hole part, etching, etc., and the measurement is extremely troublesome. Since it is impossible to detect cracks, cavities, etc., it cannot be said that it is suitable for the above-mentioned detection.

Therefore, as an easy and simple method that does not have these drawbacks, there is a resistance measurement method that measures the resistance due to the voltage drop in the plated portion.

By the way, the relationship between such resistance and plating thickness is expressed by the following equation.

R=ρT/π(D+t)t where R: resistance T; substrate thickness D; inner diameter t of through-hole; plating thickness ρ in through-hole; resistivity of plated copper In the previous equation, for example, T=1. ffmm, D=Imm, t
= 25g m, p = 1.72X 1O-6Q catosult R = 350gQ,! : If a current is passed through LA, only a minute voltage drop of 350 = v can be obtained, which is difficult to measure.

Therefore, in order to accurately measure the resistance, a four-terminal method is used in which current supply and resistance measurement are made using different contacts, and each contact is brought into contact with the upper edge and lower edge of the through hole.

As a measuring device adapted to this four-terminal method,
No. 100572, the conical electrode has a small ridge extending from its tip in the conical direction as a voltage detection contact, and the other surface serves as a current supply contact, and by insulating each of them, a current supply contact is provided to the conical electrode. and a voltage detection contact, and current supply and resistance measurement are performed by applying the conical surface of the conical electrode to the circumferential edge of a plating-covered through hole of the printed wiring board and the circumferential edge of Shimoda, respectively. There is.

By the way, through-holes on a wiring board are processed by drilling holes in a board with copper foil capped on both sides, then copper plating the inner circumferential surface of the through-hole, and electrically connecting the copper foils on both sides of the board. After that, circuits are applied to both sides of the substrate. For this reason, the through holes are drilled with a drill, and due to the curling of the substrate, they are not perfectly circular. Therefore, when the conical electrode is applied to the upper and lower circumferential edges of the through hole, the electrode does not come into contact with the entire circumferential edge, but only a part of it, and in some cases, the voltage detection contact starts from the tip of the conical electrode. Since the contact point has a small rtJ shape along the conical direction, the contact point may not come into contact with the circumferential edge of the surpole. In addition, the resistance value changes depending on the position of the upper and lower current supply contacts, but as shown in Figure 5 CI), in the above configuration, the contact part is unstable and is divided into contact lines xr and x2, so the resistance value is the same. The measured value at the through hole fluctuates,
This results in numerical values that are not reproducible. This is the sixth
A more detailed explanation will be given according to the graph in the figure.

Figure t56 shows the inner diameter of a) ■, 0φ, b) 1.2φ, c) 1.6φ for a wiring board with a thickness of 1.6 mm+ by changing the angle of the upper and lower current supply contacts using the device of the present invention, which will be described later. The voltages are measured for each through hole. This horizontal axis shows the following values: (a) when the upper and lower electrodes are arranged so that the current supply contacts are aligned vertically; (b) when the upper electrode is rotated 90 degrees in the counterclockwise direction; ) - The case where the upper electrode is rotated by 180 degrees and the case where the upper electrode is rotated by 9'00 clockwise are plotted, respectively. According to the measurement results, it can be seen that as the inner diameter of the through hole approaches the thickness of the broken wire, the resistance value becomes significantly different depending on the relative angle of the upper and lower current supply contacts. For this reason, in the conventional conical contact, the contact positions of the upper and lower current supply contacts are unstable, and the contact line is discontinuous, resulting in a constant value of 111, which is somewhat large.

The present invention is aimed at eliminating the above-mentioned drawbacks, and includes a conical surface of a conical electrode with a small 11
A voltage detection contact is formed, and a current supply contact is formed with a fan-shaped partial conical surface that is discontinuous in the circumferential direction from the detection contact and expands rearward from the tip, and each is electrically insulated. Therefore, the current supply contact is not arranged around almost the entire circumference of the conical surface, but is made into a fan shape facing the voltage detection contact, so that the voltage detection contact is surely brought into contact with the upper and lower circular edges, and the contact of the current supply contact is not broken. This is done using a contact line, and the contact position can be specified, making it optimal for measuring the plating thickness and conductivity described above.

An embodiment of the invention will be described with reference to the accompanying drawings.

FIG. 1 shows an outline of the measuring device, in which conical electrodes 4, 4 are arranged at the upper and lower parts of a through hole 2 in which a plated part 3 is formed on the inner periphery of a printed wiring board l, and the voltage is detected by the conical electrodes 4, 4. A resistance measuring device 10 is connected to the contacts 5, 5, and a DC constant current source 12 is connected to the current supply contacts 6, 6 via a measuring switch 11. The conical surface of is brought into contact with the upper and lower circular edges 2a of the through hole 2, the measurement switch 11 is closed, a current is passed between the current supply contacts 6, 6 of the upper and lower conical electrodes 4.4, and the resistance is detected as a voltage. It is detected by the resistance measuring device 10 from the contacts 5,5.

The reason why the measurement switch 11 is closed after the conical electrodes 4, 4 come into contact is to prevent the conical surfaces of the conical electrodes 4, 4 and the through hole 2 from being damaged by sparks.

The structure of the conical electrode 4 will be explained in more detail.

As shown enlarged in FIGS. 2 and 3, the conical electrode 4 has a pointed conical tip, and a small +1J surface is divided from the tip along the conical surface. , this is used as a voltage detection contact 5, and a fan-shaped partial conical surface extending backward along the cone direction from the tip at a position 180 degrees opposite to the detection contact 5 is used as a current supply contact 6, and the voltage detection contact 5. The current supply contact 6 is insulated by an insulating film 7. The voltage detection contact 5. Between the current supply contacts 6, the current supply contacts 6
Smoothly machined surfaces 8, 8 are formed of the same member with an inclination angle of approximately 45°, and as a result, the voltage detection contact 5 and the current supply contact 6 are discontinuous in the circumferential direction.

The operation of the above embodiment will be explained with reference to FIGS. 4 and 5. When the conical electrodes 4, 4 are placed on the upper and lower sides of the through hole 2 and brought into contact with the upper and lower circular edges 2a, the smooth-cut surfaces 8, 8 are It does not contact the circular edge 2a, and the width of the voltage detection contact 5 is approximately Q.
, is minute at about 2 mm and has a single narrow line edge (approximately point contact)
Therefore, the contact pressure of the through hole 2 is maintained at the voltage detection contact 5 and the current supply contact 6. Therefore, as shown in Fig. 5 (■), even if the through hole 2 is not a perfect circle, not only the voltage detection contact 5 but also the current supply contact 6 will be
line contact across almost the front mountain of the fan shape, and the contact line y
is not divided, and therefore the measurement position can be specified and stable values with reproducibility can be obtained.

In the embodiment described above, the conical surfaces are smoothed and smoothed on both sides of the voltage detection contact 5, and the fan-shaped current supply contact 6 is formed at a position 180 degrees opposite the detection contact 5. , the supply contact 6 only needs to be discontinuous with the voltage detection contact 5 in the circumferential direction, and does not necessarily need to be located at an opposite position. However, in order for the conical electrode 4 to stably contact the circular edge 2a, it is preferable that the conical electrode 4 be in a position facing the circular edge 2a at 180 degrees. Further, the conical electrode 4 may have a truncated shape.

The present invention includes, on the conical surface of the conical electrode 4, a small I11 voltage detection contact 5 extending from the tip in the conical direction, and a fan-shaped portion extending rearward from the tip, which is discontinuous with the detection contact in the circumferential direction. Since the current supply contacts 6 each have a conical surface and are electrically insulated from each other, a) Even if the through hole 2 is not a perfect circle, the voltage detection contact 5 and the current supply contact 6 can be reliably connected to the inner edge. I came into contact with 2a,
``Poor resistance measurement due to poor contact of the voltage detection contact 5 does not occur.

Mouth) Since it is always in contact with the circular edge 2a at a fixed position, reproducibility occurs in the measured values. Therefore, when making the measurement, change the contact positions of the voltage detection contact 5 and the voltage supply contact 6 to the through hole 2 and measure at several points, so that the value can be adjusted along the circumference of the through hole 2. This has the effect of making it possible to measure variations in the thickness of the plated portion along its circumference.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the measuring device, Figs. 2 to 4 show embodiments of the present invention, Fig. 2 is a side view of the conical electrode 4, Fig. 3 is an end view, and Fig. 4 shows the contact state. The side view, Figures 5 I) and 5 II) are cross-sectional plan views showing the contact state of the current supply contacts 6 in comparison with the conventional structure, and Figure 6 shows the relative angles of the upper and lower current supply contacts 6, 6, and measured values. It is a graph showing the relationship between 2; Through hole 2a; Circular edge 4; Conical electrode 5: Voltage detection contact 6; Current supply contact 'jpJ1 Fig. 20 Fig. 3 Fig. 40 No. Feng

Claims (1)

[Claims] A device that measures the resistance of the through-hole plated portion by contacting a current supply contact and a voltage detection contact with the upper periphery and lower periphery of the plated through-hole of a printed wiring board, respectively, and using the upper and lower voltage detection contacts. , on the conical surface of the conical electrode,
A small 111 voltage detection contact is formed from the tip along the conical direction, and a current supply contact is formed from a fan-shaped partial conical surface that is discontinuous with the detection contact in the circumferential direction and expands rearward from the tip. , a resistance measuring device for a through-hole plating part, characterized in that both the contacts are electrically insulated.