JPS6333678A - Substrate hold-down mechanism for in-circuit tester - Google Patents

Abstract

PURPOSE:To prevent the breakage of a part or the crack of a substrate by inserting a sensing rod provided with a switch at the center of a hold-down rod and stopping the descent of the hold-down rod when it abuts against a part. CONSTITUTION:In checking a circuit, a press 7 is operated and attachment plate 4 and hold-down rods 3 integrally descend to press a substrate 6 by the hold-down rods 3. At this time, when the hold-down rod 3 descends onto a part 14, the lower end of a sensing rod 10 is brought into contact with the part 14 and the sensing rod 10 relatively ascends with respect to the hold-down rod 3 to turn off a normally-closed switch 11 whereby a controller 12 stops the descending operation of the press 7. Since a plurality of the switches 11 are connected in series, turning off either one of them feeds an OFF signal to the controller 12 to stop the descent of the press 7, so that the breakage of the part or the crack of the substrate is avoided.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a board holder for holding a board in an in-circuit tester that checks circuits on a printed wiring board. l! Regarding the side.

[Prior Art] The above-mentioned in-circuit tester is used to test printed wiring boards in which circuit patterns are formed on an insulating substrate and electrical components are mounted.
This is a device that automatically checks a large number of items to see if the circuit is as designed. Figure 2 shows the schematic configuration of this in-circuit tester, which includes a lower attachment plate 2 on which a number of contact pins 1 are attached in accordance with the circuit pattern of the printed wiring board, and an upper attachment plate 4 on which a presser bar 3 is fixed. A printed wiring board (substrate) 6 is supported on the contact pins 1 by springs 5, etc., and the attachment upper plate 4 fixed to the ram 7a is lowered by a press 7 such as an air cylinder, and the board 6 is held down. The contact pins 1 are pressed down by the contact pins 3 to bring them into contact with the pattern on the back surface of the board 6, and then electricity is applied and circuit checks are successively performed via the contact pins 1 by the built-in circuit check device.

The presser rods 3 are arranged at a plurality of locations on the attachment top plate 4 by selecting locations where there are no components on the board 6, but unlike the conventional board presser 8! The structure was simply a rod-shaped presser rod fixed to the top plate of the attachment.

(1) [Problems to be solved by the invention] The above board holder 8! ! Although the presser bar is placed in a place where there are no parts on the board, it is lowered onto a board where parts are crowded, so for some reason,
It is difficult to completely prevent the presser bar from hitting the parts. In such a case, the above-mentioned conventional board holder 8! In the structure, even if the presser bar hits a component, it will continue to be pressed, leading to damage to the component, and furthermore, there is a risk that concentrated load will be applied to the board, causing it to crack.

This invention solves the above problems and prevents component damage and board cracking! ? The purpose is to obtain +curvature.

[Means for Solving Problem 7] In order to solve the above-mentioned problems, the present invention has a sensing rod that is movable up and down at the center of the presser rod fixed to the upper plate of the attachment, and has its lower end protruding. A switch is provided in the upper jaw of the sensing rod that turns on or off when the sensing rod is inserted and the sensing rod rises relative to the presser bar, and the switch is turned on or off before the presser rod reaches a predetermined lowered position. The structure is such that the lowering of the attachment top plate is stopped when the attachment top plate is turned off.

[Function] In the above configuration, when the C1 presser bar descends, it descends onto the component and the tip of the sensing rod protruding from its lower end comes into contact with the component, causing the sensing rod to move relative to the presser bar. rise and turn on or off the switch at its upper end,
The lowering of the attachment upper plate is stopped by the ON or OFF signal of this switch.

Therefore, the risk of the presser bar damaging the component or cracking the board is prevented.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. p
As shown in FIG. tS1, a sensing rod 10 is inserted into the center of the presser bar 3 fixed to the upper attachment plate 4 so as to be movable up and down with respect to the presser bar 3. This sensing pin 10 protrudes from the lower end surface of the presser bar 3. At the upper end of the sensing rod of the attachment upper plate 4, there is provided a switch 11 which is turned off when the sensing rod 10 is raised relative to the presser rod 3 and is turned off at all times. This switch 11 is provided for each patient detection bar 10 of each presser bar 3 provided in plurality on the attachment upper plate 4, and these switches 11
are connected to the control section 12 in series. Reference numeral 13 denotes a position sensor, and this position sensor 13 is arranged to detect when the attachment upper plate 4 is lowered to a position where the lower end of the patient detection rod 10 contacts the substrate 6, or to a position just before that. There is.

In the above configuration, when a circuit check is performed, the press 7 is operated and the attachment upper plate 4 and the presser bar 3 are lowered together to press the board 6 by the presser bar 3. At this time, as shown in FIG. 3 descends onto the component 14, the lower end of the sensing rod 10 contacts the component 14, and the sensing rod 1
0 is raised relative to the presser bar 3, and the switch 11, which is always on, is turned off, and in response to the off signal from this switch 11, the control section 12 stops the lowering operation of the press (F-silling) 7. Furthermore, since the plurality of switches 11 are connected in series, even if any one of them is turned off, that is, no matter which presser bar 3 hits the part, an off signal is sent to the control unit 12 and the lowering stops. do. In this case, the force applied to the component 14 is the switch 1 of the patient detection stick 10.
The contact force is only necessary to operate the presser bar 3, and the presser bar 3 stops before the pressing force is applied, thereby avoiding damage to parts and cracking of the board.

In addition, in the normal case where the push rod 3 descends to a place on the board 6 where there are no parts, the position sensor 13 detects the attachment top plate 4, and the position where the Uchi Azusa 10 contacts the board 6, Alternatively, it is detected that the press has descended to the position just before that position, and the stop of the press lowering operation is released. Therefore, in such a normal case, pressing continues as it is, and the presser bar 3 presses down the substrate 6. As a result, each contact pin 1 comes into contact with a respective position of the circuit pattern on the back surface of the board 60, and then electricity is applied and a circuit check is performed.

Note that as for the switch 11, various types such as a small microswitch can be used.

Further, as a means for detecting that the presser bar 3 has correctly descended onto the root with no parts, the position sensor 13 of the embodiment is used.
However, various methods can be considered, such as a method of numerically measuring the amount of descent of the attachment upper plate 4 itself.

In addition, although the switch 11 that is always on is used in the embodiment, it is naturally possible to use a switch that is always off and stop the lowering of the attachment top plate 4 when the switch is turned on by the sensing rod 10. It is.

[Effects of the Invention] As explained above, according to the present invention, a sensing rod is inserted into the center of the presser bar with its lower end protruding so as to be movable up and down, and a switch is provided at the upper end of the sensing rod, so that the presser bar can be moved vertically. When the switch is turned on or off before the predetermined lowering position is reached, the lowering of the attachment top plate is stopped, so if the presser bar hits a component, the lowering of the presser bar is stopped, It is now possible to prevent component damage and board cracking.

[Brief explanation of drawings]

FIG. 1 is a front view of a convex temporary holding margin hv showing an embodiment of the present invention, and FIG. 2 is a schematic diagram of an in-circuit tester. 3...Pushing nine sticks, 4...Attachment top plate, 6...
...Printed wiring board, 10...Sensing rod, 11...Switch, 13...Position sensor.

Claims (1)

[Claims] A sensing rod is inserted into the center of the presser rod fixed to the top plate of the attachment so that it can move up and down and its lower end protrudes, and a switch that turns on or off is sensed when the sensing rod rises relative to the presser rod. A board holding mechanism for an in-circuit tester, which is provided at the upper end of the bar and stops the lowering of the attachment top plate when the switch is turned on or off before the holding bar reaches a predetermined lowering position.