JPS5945105B2 - Automatic testing method and device for printed board circuits - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for testing printed board circuits, and more particularly to an automatic testing method for testing according to input data using an adapter provided with a large number of contacts.

Printed circuit boards usually have a number of insertion holes for mounting components and at least one connecting circuit that short-circuits two or more of the insertion holes. As the adapter, a common adapter is used in which contacts are arranged at all positions for the predicted insertion hole arrangement so that it can be used no matter how the arrangement of the insertion holes of the printed circuit board under test changes. The switches for each contact are then conveniently arranged with the same address corresponding to the address of every position relative to the expected placement of the insertion holes on the printed circuit board. Tests between a certain address and other addresses are performed sequentially from the lowest address to the highest address. The test at each address is based on the input data from the testing machine's central processing unit, and if there is an address with a circuit connection at a higher level than that address, at least a continuity test with the first address and a continuity test with the address at a lower level than that address are performed. It is now possible to perform insulation tests between all addresses.

However, if the circuit component insertion hole is not formed in the address to be tested and a connection circuit between other addresses happens to pass through this, the contactor may not stably contact the circuit. This tends to occur, and therefore, the measured results are often judged to be incorrect. Note that the contact at this address is originally unnecessary for testing this printed board, and therefore the contact at this address is called a surplus contact in this case. Therefore, in conventional test equipment of this kind, in order to prevent the above-mentioned surplus contacts from coming into contact with the printed circuit board, contacts are freely placed only at addresses corresponding to the circuit component insertion holes according to the type of printed circuit board. Tests were conducted by making an insulating sheet (also called a mask) with holes drilled through it and placing it between the printed circuit under test and the common adapter.

This testing method enables reliable inspection of printed circuit boards and has been widely used in practice. However, this test requires a considerable amount of time, so
From the perspective of mass production, this was not necessarily satisfactory. For example, testing a printed circuit board with several thousand addresses can often take several minutes, depending upon the number and arrangement of connected circuits contained therein. The reason for this is that, as will be explained in detail later, the insulation test at one address requires a considerable number of times except for those near the lowest level, and the number of addresses to be tested for insulation (insertion holes with no connection circuits) This is because the sum of the number of contacts and the number of surplus contacts blocked by the mask) is generally quite large. If the input data from the Nazurin central processing unit is properly configured, there will be no need to perform unnecessary insulation tests from the latter's surplus contacts, but
Such software is complex and undesirable in actual testing. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an automatic test method for printed board circuits that eliminates the need to perform unnecessary insulation tests from surplus contacts without complicating the software, and a mask for use in this method.

In short, the method of the present invention consists of all the surplus contacts (divided into two or more groups depending on their arrangement).
They are connected using conductors, as if a connecting circuit was formed at the corresponding position on the printed board. That is, the automatic testing method for printed board circuits of the present invention includes a common adapter in which a contactor that can contact each address is arranged for a large number of predicted component placement addresses of a printed board under test, and a common adapter and a contactor that can be contacted at each address. Used contacts that are placed between test printed boards and that correspond to at least the addresses necessary for testing this printed board under test can be easily inserted, but surplus contacts that correspond to addresses that do not require testing must be inserted as described above. In a test method in which continuity and insulation tests are performed between contacts using a mask that prevents contact, the mask includes a large number of contact areas of the redundant contacts on the side of the common adapter. forming one or more, preferably one, electrical conductor;
This test method is characterized in that the test is performed by connecting surplus contacts corresponding to the conductor to each other in a circuit connection state. Further, the mask used in the above tests of the present invention is characterized in that the common adapter side thereof includes at least a portion that is in contact with a contact and forms one or more conductors.

Next, a detailed explanation will be given with reference to the drawings.

FIG. 1 shows a cross-sectional view of the structural parts of an apparatus for carrying out a conventional automatic testing method for printed circuit boards.

Some parts of the diagram are exaggerated to make it easier to understand. In the figure, 11 is a printed board, 12 is a plated component insertion hole, 13 is a circuit connecting between the component insertion holes, and 14 is a circuit between other component insertion holes not shown in this figure. 15 is a contact holder, 16 is a contact slidably held by this holder and elastically pushed in the direction of the printed board 11 by a spring 7, and 17 is an insulator. A sheet or mask 18 formed of material is a mask hole drilled to allow the tip 16 of the contact to be inserted without contact. In this specification, the contact tip 16 and the holder 15 are collectively referred to as a contact in the general description. Figure 2 shows an outline of the general configuration of an apparatus for testing printed board circuits, and 21 is a common adapter in which a number of contact holders 15 of Figure 1 are fixed in a frame (not shown). and 22
is a switch group.

In the figure, the switches at addresses 3 and 5 are connected, so the test can be performed between the insertion holes at 3 and 5 (insulation test in this case) by contacting the same address number. It has become a state of affairs. The selection of the two switches to be connected is performed using a decoder (not shown) in response to a selection signal from the central processing unit 23 based on test data input from the magnetic tape MTl, paper tape PT, etc. The central processing unit 23 also determines whether the test result matches pre-given continuity or discontinuation data, and outputs the result to the typewriter 24. In this figure 2, one of the switches to be connected is set to 4.
Then, the contact 16 of this address 4 is masked 17
The test is an insulation test because it is made of insulating material.
At this time, a pulse signal is sent to address 3, and confirmation is made by not receiving a signal from address 5 even after a certain period of time has elapsed. If there is a circuit connection between addresses 3 and 5, the test will send a pulse signal to address 3,
Confirm that the same waveform returns from address 5. Next, it will be explained how many times the test is required when performing the test as described above.

Figure 3 is a diagram explaining the required number of tests using the above configuration.The 19 small circles indicate the contacts for the predicted component arrangement if the printed circuit board circuits are arranged in a line, and the white circles indicate the number of tests required. The redundant contacts for addresses without component insertion holes are indicated by black circles, and the black circles indicate used contacts for addresses with component insertion holes.

Further, solid lines connecting the contacts used indicate that there is a circuit connection. In the first test, first close the switches at addresses 2 and 1 (hereinafter, when referring to address numbers, only the numbers are written), and conduct an insulation test between the redundant contacts of 2 and the redundant contacts of 1. Next, a total of two insulation tests are carried out between contact 3 and 1, and a continuity test is conducted between contact 7 and the contact 7 connected to the circuit. For contacts with no circuit connection, such as surplus contacts 4, used contacts 5, and surplus contacts 6, the addresses in the opposite direction to the test order are Each contact is tested for insulation three times, four times, and five times.

Regarding the contact used in No. 7, the continuity test with No. 3 has already been completed and there is no subsequent contact, so no test will be conducted in this case.

If the test is repeated in the same way, a total of three continuity tests will be required, but a total of 137 insulation tests will be required. The large number of small black dots shown in FIG. 3 are a result of the insulation test described above. Note that the continuity test was performed only three times, so it is not shown. In this way, a total of 140 tests are required. For your reference, if all addresses are not connected to the circuit, the number of insulation tests is 19 (19
-1)/2, or 171. As described above, when using the conventional method, the number of tests is extremely large.

Of course, this is unavoidable if all the test results are necessary, but as mentioned earlier, testing from the extra contacts during these tests is not originally necessary for testing printed circuit board circuits. Of course, software that prevents unnecessary tests from being performed on input data would be complicated and ineffective. In addition, when testing the insulation of one contact, it is not necessary to test between contacts that are connected to the circuit before this contact, but this test is performed infrequently and the input data becomes complex as described above. , usually all tested. FIG. 4 shows a cross-sectional view of the structural part of an apparatus for carrying out the automatic testing method for printed board circuits of the present invention. The difference from FIG. It consists of a metal film 34 deposited on the side of the contact 33.

FIG. 5 is a diagram of the mask 31 seen from the side of the metal film 34, where the cross mark indicates the position of the contact, the inner circle of the double circle indicates the edge of the hole 35 of the insulating sheet 32, and the two circles indicate the position of the contact. In the middle, the edge of the metal layer 34 is slightly retracted and the insulator 32
It shows that a part of the image appears ring-shaped. Therefore, in the insulation test, the four surplus contacts (all of which form a common adapter) shown in FIG. It works the same way as it does.

Therefore, the input data for the test includes information that these extra contacts are connected to the circuit, and the following test is performed. FIG. 6 is a diagram for explaining the necessary circuitry for the insulation test in the above-mentioned test method of the present invention. In this figure, the connections indicated by dotted lines indicate circuit connections by the insulating film 34, and are substantially the same as the circuit connections indicated by solid lines on the opposite side. First, surplus contact 2 is connected to the previous surplus contact 1, so an insulation test is not performed, but a continuity test is performed with the next surplus contact 4 belonging to the same circuit connection. Do only. For the next three contacts to be used, an insulation test is performed between the second surplus contact and the first surplus contact, and a continuity test is performed between the next contact 7 in the same circuit connection. In the next 4 extra contacts,
Extra contact 6 corresponding to the test on extra contact 2
Perform only a continuity test between the Although the explanation is omitted below,
The drawing shows only the insulation test among these tests, making a total of 38 tests. Although the continuity test is not shown in the figure, it is carried out 10 times. Therefore, the number of required tests is 48 times in total. Comparing this figure with the conventional case, it is 48/140, or about one-third, and the measurement time can be reduced by that proportion.

As can be seen from the above explanation, the number of insulation tests in the test method of the present invention is determined by the number of single contacts used without circuit connections and the number of connected circuits on the printed board. As these numbers become smaller, the aforementioned proportion becomes smaller and smaller. For a certain printed circuit board circuit with about 4,000 contacts that is currently being planned and is currently being prototyped, testing would have taken about 5 minutes using the conventional method;
In some cases, the method of the present invention has been found to require only about 30 seconds. As described above, according to the present invention in which the structure of the mask and the input data are improved, it is no longer necessary to perform an insulation test on surplus contacts, and the time required for the test can be significantly shortened.

In the above description, the number of conductors 34 formed on the surface of the mask is one over the entire surface of the mask, but there may be two or more conductors 34 depending on the arrangement of the pins used.

However, each time an additional pin is added, an insulation test is required from the first surplus pin, so the time required becomes slightly longer. Also, conductor 3
The reason why the edge of 4 is missing is to ensure that the test can be performed correctly even if the contact comes into contact with this part. If you leave it on, you won't necessarily need this missing part.

Furthermore, in the above embodiment, only the reverse insulation test is performed for contacts without a circuit connection, and for contacts with a circuit connection (extra contacts are also included in this category due to the conductor 34): At the first address, perform one reverse insulation test and a continuity test for the next address, and at the next address, if there is a next address, simply perform a continuity test with this next address. The reverse insulation test is not performed, the same procedure is repeated if any, and no test is performed on the last address.

However, it goes without saying that the use of a mask provided with a conductor is not necessarily limited to the above-mentioned test method, and other methods may be used. In short, any method can be used as long as it can take advantage of the feature that redundant contacts are connected to each other in a circuit during measurement.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a cross section of the structural part of a device for carrying out a conventional automatic testing method for printed board circuits, and Figure 2 is a diagram showing an outline of the configuration of the equipment for testing printed board circuits. , FIG. 3 is a diagram illustrating the required number of tests with the above configuration, and FIG. 4 is a diagram showing a cross section of a structural part of an apparatus for carrying out the automatic testing method for printed board circuits of the present invention. FIG. 5 is a top view of a mask used in the test method of the present invention, and FIG. 6 is a diagram illustrating the required number of tests using the above configuration. Explanation of symbols: 11 is an insulating board (printed board), 221 is a common adapter, 22 is a switch group, 23 is a central processing unit,
31 is a mask, 32 is an insulating sheet, 33 is a contact, 34
indicate conductors, respectively.

Claims (1)

[Scope of Claims] 1. A common adapter in which contacts capable of contacting each address are arranged for a large number of expected component placement addresses of a printed board to be tested, and a common adapter placed between this common adapter and the printed board to be tested. , so that at least the used contacts corresponding to the addresses necessary for testing the printed board to be tested can be easily inserted, but the extra contacts corresponding to addresses that do not need to be tested are prevented from contacting them. In the test method, the continuity test and the insulation test between the contacts are performed using a mask, in which the mask includes one or more contacts on the side of the common adapter that include many of the portions that the redundant contacts contact. , preferably one,
An automatic test method for a printed circuit board, which comprises forming a conductor, and testing is performed by connecting redundant contacts corresponding to the conductor to each other in a circuit connection state. 2. In order to be placed between the printed board under test and the common adapter equipped with a large number of contacts, the contacts can be easily inserted into the position corresponding to the usage address of the component arrangement required for testing on the printed board under test. In a mask with many holes,
A mask for use in a printed circuit board test, characterized in that the common adapter side of the mask includes at least a portion of the contact that corresponds to the mask to form one or more conductors. 3. The mask according to claim 2, wherein the conductor is omitted near the hole.