WO2013004775A1

WO2013004775A1 - Adapter for an examination apparatus and examination apparatus for testing printed circuit boards

Info

Publication number: WO2013004775A1
Application number: PCT/EP2012/063109
Authority: WO
Inventors: Victor Romanov; Andreas Gülzow; Bernd-Ulrich OTT
Original assignee: Dtg International Gmbh
Priority date: 2011-07-06
Filing date: 2012-07-05
Publication date: 2013-01-10
Also published as: DE102011051607A1; TW201303331A

Abstract

The present invention relates to an adapter for a parallel tester for testing bare printed circuit boards and to a parallel tester for testing bare printed circuit boards. According to the invention, in each case at least two test needles (19) are arranged in a plurality of guide holes (22) in a test-article contacting plate (15) that can be arranged adjacent to a test article (6), and said test needles (19) are electrically insulated from each other. It is thus possible to carry out a four-wire measurement in a parallel tester and still provide a high density of contact locations.

Description

Adapter for a tester and tester for testing printed circuit boards

The present invention relates to an adapter for a test apparatus and a test apparatus for testing printed circuit boards. In particular, the present invention relates to an adapter for a parallel tester for testing bare printed circuit boards and a parallel tester for testing bare printed circuit boards.

Devices for testing printed circuit boards are fundamentally subdivided into two groups, the finger testers, which serially scan test points of a printed circuit board under test with a plurality of contact fingers, and the parallel testers, which contact all test points or board test points of a printed circuit board to be examined simultaneously by means of a multiplicity of contacts ,

The parallel testers once again differentiate between the universal tester and the dedicated tester.

Universal testers are parallel testers with a basic grid. The basic grid is a regular grid of contact points, which are connected to an evaluation device. Since the board test points to be tested a printed circuit board to be tested are normally arranged in a grid deviating from the regular grid of the basic grid, it is necessary to provide an adapter, which connects in each case a circuit board test point of the printed circuit board to be tested with a contact point of the basic grid. Such adapters are also referred to as Rasteranpassungsadap- ter, since they implement the predetermined, regular basic grid of the tester on the usually irregular arrangement of the board test points of a circuit board to be tested. Such an adapter generally has a plurality of spaced apart guide plates, in which guide holes are introduced for receiving test needle. The test needle can be arranged obliquely in the adapter, so that the contact points of the regular basic grid can electrically connect to the circuit board test points, which generally differ from the regular arrangement of the basic grid.

In general, the adapter is not arranged directly on the basic grid, but it is provided between the basic grid and the adapter, a so-called full grid cassette. A full grid cassette is similar to the adapter formed of a plurality of guide plates, in which contact pins are arranged in the same grid as the basic grid. These pins are resilient. The reason why such a full raste cassette is used is that it is difficult to insert resilient contact pins into the adapter because they are too thick to be able to arrange them diagonally in the adapter can. On the other hand, it is necessary that differences in height due to unevenness in the circuit board to be tested or due to the inclination of the needles in the adapter can be compensated by the resilient contact pins of the full grid cassette.

Instead of a full grid cassette, an elastic conductive rubber plate can be provided, which establishes an electrical connection between the needles of the adapter and the corresponding contact points of the basic grid. For a type of printed circuit board to be tested, a special adapter must be produced in each case. The basic grid and the full grid cassette, however, are independent of the type of printed circuit board to be tested. Such parallel tester with a basic grid is also called universal tester, since only the adapter is specific to the respective printed circuit board. to adapt to the type of tent. The remaining components of the test apparatus can be used to test any type of board.

By contrast, the dedicated testers are parallel testers which have a contact plate in which contact elements are arranged in the grid of the board test points of the circuit board to be tested. The contact elements of the contact plate are connected individually with wires or thin cables directly to the connection points of an evaluation or an evaluation. Such dedicated testers are used primarily for testing microchips (ICs). However, they are also increasingly being used in the testing of printed circuit boards, in particular if the printed circuit boards have very small printed circuit board test points arranged close to one another. However, the production of the contact plate is very expensive, since the individual contact elements must be soldered by hand with the appropriate cables. Dedicated testers are therefore disadvantageous in the case of large-area, bare printed circuit boards, which at the same time have to contact thousands of printed circuit board test points.

From EP 875 767 B1, a parallel tester emerges, which has a basic grid plate on whose surface a basic grid is formed. The basic grid plate is a multi-layer printed circuit board, wherein a plurality of contact points of the basic grid are electrically connected to one another by means of scan channels extending in the basic grid plate. Thus, a plurality of contact points of the basic grid, which are each linked to one of the scan channels, are electrically connected to one connection each of an evaluation electronics. As a result, multiple contact points of the basic grid can be operated with a connection of the evaluation electronics, whereby it is possible to provide the contact elements of the basic grid in high density, without the capacity of evaluation must be increased accordingly. On the basic grid an adapter and / or translator, on which the printed circuit board to be tested can be placed.

WO 02/31516 A1 discloses a module for a parallel tester which has a strip-shaped section with contact points, which forms part of a basic grid of the parallel tester. Below the strip-shaped section is a arranged vertically standing plate on which a part of an evaluation for the evaluation of test signals is arranged. The contact points on the strip-shaped section are arranged in a grid with a grid spacing of not more than 2 mm and at least two contact points of a module are electrically connected to one another such that the electrically connected or linked contact points are in contact with a single input of an evaluation electronics stand.

WO 2008/071541 A2 discloses another module for a parallel tester for testing circuit boards. This module has a support plate and a contact plate. The contact plate is formed of a rigid circuit board portion referred to as a basic screen member and at least one flexible circuit board portion. At the base grid contact points are provided, each forming a part of the contact points of the basic grid. The basic screen element is arranged on an end face of the support plate and the flexible printed circuit board section is bent in such a way that at least part of the remaining area of the contact plate is arranged parallel to the support plate. The contact points of the basic grid element are each in electrical contact with conductor tracks running in the contact plate, which extend from the basic grid element into the flexible conductor section. A large number of such modules are arranged next to one another in the parallel tester, so that the basic grid elements form a continuous base grid plate, on which the basic grid is shown in the form of contact points arranged in a regular grid.

The construction of an adapter can be seen, for example, from WO 2009/047160 A2 or US 2010/0283498 A1.

DE 44 41 347 A1 discloses a method and a device for testing populated assemblies by means of a four-wire measurement. For this purpose, at least four needles which are freely movable in the X and Y directions are provided. Testing populated assemblies requires significantly fewer contacts than testing bare PCBs. When testing unpopulated printed circuit boards, each trace must be contacted separately, whereas when testing populated assemblies, a bump test or in-circuit test can be performed the function of a complete electrical circuit with a few contacts is tested.

Test probes for a finger tester for carrying out the four-wire measurement are described in US Pat. No. 6,384,614 B1.

EP 1 031 840 A2 discloses a test device for testing printed circuit boards, in which the electrodes can be brought into contact with the contact points of the test object by means of an electrically conductive elastomer layer. This electrically conductive elastomer layer is designed so that it reduces its electrical resistance in the compression direction when compressed. As a result, the individual electrodes in the contact plates can be arranged very closely adjacent and nevertheless an individual contact to the test points of the printed circuit board can be produced. The arrangement of the electrodes may even be formed so close adjacent that two adjacent electrodes together contact a contact point of a printed circuit board, wherein via the one electrode, a measuring current is supplied and the voltage is measured by means of the other electrode.

The document DE 197 15 094 A1 describes an adapter for testing printed circuit boards, which consists of a minimum number of individual parts and can be assembled quickly and easily. This adapter has a plurality of guide plates in which holes are drilled. Needle-shaped test probes are stored in the holes. An upper guide plate has holes in a standard grid arrangement that corresponds to the grid arrangement of the contact points of an electronic test or analysis device. The bottom plate is provided with an array of holes drilled according to the locations of the test points of the circuit board to be tested. Each hole of the upper plate is associated with a respective hole in the lower plates. A needle-shaped test probe is inserted into these corresponding holes so that the probe is held at each plate level. The invention has for its object to provide an adapter and a parallel tester, with which it is possible to test unpopulated printed circuit boards with a high density of contact points very precise. The object is achieved by an adapter with the features of claim 1 and by a parallel tester with the features of claim 9. Advantageous embodiments of the invention are specified in the respective subclaims.

An inventive adapter for a parallel tester for testing unpopulated printed circuit boards comprises

at least one master grid guide plate and a test fixture guide plate, the master grid guide plate having guide bores arranged in a regular grid whose grid corresponds to a basic grid of a parallel tester,

and the sample guide plate has patterned guide holes corresponding to the pattern of board test points of a printed circuit board to be tested, and

Test probes, each bearing one end portion in one of the guide holes of the base grid guide plate and the other end portion in one of the guide holes of the sample guide plate.

The invention is characterized in that in each case at least two test needles are arranged in several guide bores of the Prüflingsführungsplatte and arranged jointly in guide bores of the Prüflingsführungsplatte test needles are insulated from each other.

Since at least two test probes are arranged in each case in a plurality of guide bores, the corresponding circuit board test points are contacted simultaneously with two test probes, so that a four-wire measurement can be carried out at these circuit board test points. A four-wire measurement is much more accurate than a 2-wire measurement. There have been attempts with adapters where the pilot holes are so close together that two test probes can simultaneously contact a board test point of a board to be tested. This also allows a four-wire measurement. However, the density of the printed circuit board test points to be contacted is low, since the two guide holes require much more space than the guide bore according to the invention for receiving two test pins.

The fact that the test needles are insulated from one another ensures that the test probes arranged together in the guide bore independently contact the respective circuit board test point, so that the contact resistance between the test probes and the respective circuit board test point can be reliably eliminated. If there was an electrical contact between the two test probes, then the current flows through the two needles could not be separated cleanly.

In order to isolate the test probes located together in a guide bore, at least one of the test needles has an electrically insulating coating which comprises at least the portion of the test needle located in the region of this guide bore, wherein a tip of the test needle adjacent thereto is not coated. Preferably, all located in the guide hole test pins are coated.

The coating is preferably formed from aluminum oxide, titanium oxide or from a carbon coating.

However, the test probes may also be electrically insulated from each other by means of a thin foil placed between the test probes. In this case, it is possible for the film to partially surround at least one of the test needles in the form of a sleeve. The film consists of an abrasion-resistant plastic, in particular a fiber-reinforced plastic.

A parallel tester according to the invention comprises

a Prüflingskontaktierungsplatte arranged in a predetermined pattern Holes corresponding to the pattern of circuit board test points of a printed circuit board to be tested, wherein a plurality of pairs of test pins are respectively disposed in a common bore of the Prüflingskontaktierungsplatte with one of its end portions, so that contacted with a arranged in a bore pair of test probes each a circuit board test point of a circuit board to be tested can be.

The parallel tester can be designed as a universal tester with a basic grid and an adapter described above. However, the parallel tester can also be a dedicated tester, the test probes being connected by means of wires or cables directly to an evaluation device. In the case of the dedicated tester, the test probes arranged together in a bore are preferably also electrically isolated from one another, wherein the electrical insulation can be realized by means of one of the above-explained coatings and / or by means of a foil. Preferably, the parallel tester is designed such that each of the test probes is electrically connected to a terminal of an evaluation device, wherein two or more test needles are each connected to the same terminal of the evaluation, and connected to the same terminal of the evaluation test probes are in each case arranged different holes in the Prüflings- contacting plate. This principle of linking groups of test probes and connecting the group of test probes to a common terminal of the evaluation device is known from EP 875 767 B1. In the case of a universal tester with a basic raster plate, the linkage can take place by means of scanning channels running within the base raster plate, and in the case of a dedicated tester, a plurality of wires or cables can be connected directly to a connection of the evaluation device.

The combination of pairs of probes, which are arranged together in a bore of the Prüflingskontaktierungsplatte, and the combination of several test needles different holes is particularly advantageous because the number of probes per parallel tester increases by the arrangement of at least two probes in each hole , where by linking test probes the capacity of the evaluation device or the evaluation must not be increased accordingly.

The invention will now be described by way of example in more detail with reference to the drawings. The drawings show in:

1 shows a detail of an adapter and a full grid cassette in a sectional view,

2 shows the boundary region between the adapter and the full grid cassette from FIG. 1 in an enlarged view, FIG.

3 shows a guide bore of the adapter of FIG. 1 with two test probes in a sectional view, FIG.

4 shows an alternative embodiment of an adapter in the region of a guide bore with two test probes in a sectional view,

Fig. 5 shows a parallel tester (universal tester) with full grid cassette and adapter schematically simplified in an exploded view, and

Fig. 6 shows a parallel tester (Dedicated Tester) schematically simplified in an exploded view. The invention is first explained by means of a parallel tester in the form of a universal tester (FIGS. 1 to 5).

Such a parallel tester has a plate-shaped basic screen element 1 (FIG. 5) which has a plurality of contact points in the form of contact surfaces which are arranged in a regular grid. These contact points of the basic grid element 1 are each connected to a terminal of an evaluation device or evaluation electronics 2. The basic grid element 1 may be formed from a plurality of strip-shaped modules 3, as e.g. from the US 7,893,705; or EP 1 322 967 B1 are known.

On the basic grid element 1, a full grid cassette 4 is arranged, which has spring contact pins 5. The spring contact pins 5 of the full grid cassette 4 are arranged in the same grid as the contact points of the basic grid element 1, so that each contact point of the basic grid element 1 touches a spring contact pin 5 and is electrically contacted. The spring contact pins 5 are arranged parallel to each other. The electrical connection between the arranged in the regular grid spring contact pins 5 and the irregularly arranged contact points of a circuit board to be tested 6, which are referred to below as printed circuit board test points, is made via an adapter 7. The adapter 7 is formed of a plurality of mutually parallel guide plates 8 (Fig. 1). Adjacent to the full grid cassette 2, a plate pack 9 is arranged with two plates having holes in the grid of the arrangement of the spring contact pins 5 of the full grid cassette 4 and the contact points of the basic grid. This plate pack is referred to below as the basic grid unit 9 or GR unit 9. The GR unit 9 is composed of a cover plate 10 and a structural plate 1 1. The cover plate is disposed immediately adjacent to the full grid cassette 4 and has a thickness of 1, 5 mm. The structural plate 1 1 is applied to the cover plate 10. It has a thickness of 3 mm and gives the adapter the necessary mechanical strength on the side facing the full grid cassette. Since the basic grid unit has 9 holes in the grid of the arrangement of the spring contact pins 5 of the full grid cassette 4 and the contact points of the basic grid, the two plates 10, 1 1 of the basic grid unit respectively a Grundrasterfüh- approximately plate 10, 1 1 represents. With some distance to the structural plate 1 1, a holding plate 12 is arranged. The holding plate 12 has a thickness of 3 mm.

Four thin guide plates 8 are arranged at a distance from each other. They each have a thickness of 0.3 mm. The number of guide plates varies depending on the size of the surface that is to be covered with an adapter (= test field) and on the maximum offset of the printed circuit board test points with respect to the corresponding contact points of the basic grid and thus the thickness of the adapter. At the PCB facing side of the adapter 7 is a Plate unit provided with three plates, which is hereinafter referred to as PCB unit or LP unit 13. The LP unit 13 is composed of a structural plate 14, a guide plate 15 and a cover plate 16. The structural plate 14 gives the LP unit 13 the necessary mechanical strength. This structural plate is formed in the present embodiment with a thickness of 4 mm.

The cover plate 10 and the cover plate 16 are bolted outside the test field with the other plates 1 1, 14 of the adapter. These screw connections can thus not influence the electrical properties of the adapter.

The guide plate 15 is again a thin guide plate with a thickness of 0.3 mm. In such a thin plate, the bores for guiding the probes and pins can be more easily inserted with high precision than in the thick structural and holding plates. The guide plate 15 and the cover plate 16 has a drilling pattern corresponding to the pattern of the board test points and thus ensures that the test pins of the adapter 7 are aligned exactly with the board test points. All plates, with the exception of the cover plates 10, 16, are kept at a distance by several column mechanisms 17, which are known per se. Alignment pins 18 extend between the GR unit 9 and the LP unit 13 and engage in each case in a form-fitting manner through a hole in the holding plate 12 and the guide plates 8, so that the plates 8, 12 are exactly aligned with one another. The alignment pins also serve as spacers between the basic grid unit 9 and the printed circuit board unit 13.

The adapter 7 has probes 19 which are guided in the guide plates 8, 15. The test needles 19 are used to contact Padfeldern on the circuit board to be tested 6. In addition to the test needles 19 and pins 20 may be provided in the adapter. The contact pins 20 are provided for contacting vias of the printed circuit board 6. The test needles 19 may be formed with different diameters. The test needles 19 each have a circular cross-section. They are each provided with a thickening 21 at their ends pointing towards the full-raster cassette. This thickening 21 may be formed by a plugged or shrunk on sleeve or by a pinch of the test needle 19. A pinch is easier and cheaper to produce. However, it requires a certain thickness of the test needle and is particularly suitable for thicker probes. For thinner test probes, it is more expedient to provide an additional sleeve. Stepped bores for receiving the thickenings 21 of the test probes 19 are provided in the cover plate 10 (FIGS. 1, 2). These stepped holes serve that the test needles 19 with their thickening 21 can not be moved through the plate 10 and thus secured against falling out in the direction of the side of the circuit board to be tested 6. The test needles 19 are freely movable in the direction of the full-raster cassette 2 in the adapter 7.

The thin guide plates 8, 15 are provided with substantially smaller through holes than the two cover plates 10, 16, the structural plate 1 1 and retaining plate 12. The position of the test pins 19 is thus essentially determined by the through holes of the thin-walled guide plates 8, 15. The arranged on the Prüflingsseite the adapter 7 guide plate 15, which is part of the printed circuit board unit 13 and is located between the pattern plate 14 and the cover plate 16, hereinafter referred to as Prüflingsführungsplatte, since arranged in this guide plate 15 through holes in the pattern of PCB test points of a circuit board to be tested (DUT) 6 are arranged. According to the invention, at least two test pins 19 are arranged in a plurality of through bores of the test piece guide plate 15. Figure 3 shows such a through hole of the Prüflingsführungsplatte 15, which is also referred to as a guide bore 22 through which two test pins 19 extend. The corresponding through-holes in the adjacent structural plate 14 and cover plate 16 are dimensioned so large that they do not come into contact with the test needles 19. The position of the probes 19 is thus determined solely by the guide bore 22 in the Prüflingsführungsplatte 15. The test needles 19 have a conical tip 23 and an adjoining cylindrical base body 24. In the region of the base body, the test needles have a diameter of about 80 μππ. The diameter is preferably in the range of 70 μππ to 100 μππ and in particular in the range of 75 μππ to 85 μππ. The test probes are made of metal, in particular a highly conductive copper alloy. The guide bore 22 of the present embodiment has a diameter of about 180 μππ. The diameter of the guide bore may be in the range of 170 to 190 μππ.

The test pins 19 are provided with an insulating coating 25 on the portion extending through the sample guide plate 15. The coating 25 is, for example, a ceramic coating of aluminum oxide or titanium oxide. It may also be a carbon coating, wherein the carbon is present in an electrically non-conductive structure similar to the diamond structure. These coatings form abrasion-resistant coatings, so that even with a repeated mutual rubbing of the test pins 19, the insulation is ensured in the long term. The coating extends from the area of the cone-shaped tip 23 in the direction of the solid grid cassette end of the test probes 19 so far that it is ensured that two adjacent test probes can not come into contact with the uncoated area. The specimen-facing region of the conical tip 23 is free of the insulating coating 25 in order to make electrical contact with the circuit board test point 6 of the test piece. Preferably, however, the coating also extends over a portion of the conical tip 23. In the present embodiment, the conical tip 23 has an angle of about 90 degrees. However, the conical tip may also be formed with a smaller angle.

The two probes 19 in a guide bore 22 come into contact with the same circuit board test point of the printed circuit board to be tested, so that by one of the two test probes 19, a measuring current can be passed with a predetermined current and the voltage with the other test needle, at the corresponding conductor track in the PCB to be tested drops, can be removed. The- This measurement principle is also referred to as four-wire measurement. When determining the ohmic resistance of the measured conductor track of the circuit board to be tested, the contact resistance between the test pins 19 and the circuit board test point is eliminated in the four-wire measurement. This makes this measurement very precise.

In the embodiment shown in Figure 3 extends through the through holes of the other guide plates 8 only a single test needle 19, so that the test needle 19 are spatially separated from each other in the region of the other guide plates 8.

In an alternative exemplary embodiment (FIG. 4), two test needles 19 each are guided through a guide bore 22 of the test object guide plate 15 as well as through a through bore of a guide plate 8 adjacent to the test object guide plate 15.

In this arrangement, the area in which the two probes 19 can touch, much larger, which is why the section in which the two probes 19 are electrically isolated, is to be formed correspondingly longer. This means that the coating extends from the region of the tip 23 further towards the opposite end of the test probes than in the embodiment according to FIG. 3. This section thus still extends through the guide plate 8 arranged adjacent to the printed circuit board unit 13. The advantage of this Embodiment is that the portion of the test probes, which is adjacent to the test circuit board, is less inclined to a vertical to the guide plates 8, 15 and to the test printed circuit board as in the embodiment of Figure 3. This lesser inclination in the portion adjacent the specimen results in the ends of the tip 23 of the two probes 19 located in a guide bore 22 being closer together, allowing smaller printed circuit board test points to be contacted. The test pins 19 are flexible, so that they can be bent away from each other by the guide by means of the further guide plate 8 with the other sections. Internal, unpublished attempts have been made to make an adapter with probes with all the probes in separate through-holes in the sample-guide plate, however, the probes and bore should be chosen small enough to allow four-wire measurement. This would theoretically possible with test probes with a diameter of 60 μππ and holes with a diameter of 80 μππ, wherein the minimum distance between the edges of two holes is 40 μππ. On the one hand, it is difficult to correctly insert such small holes in a guide plate. Although this is expensive, but in principle possible with the existing technical means. However, it has been shown that test needles with a diameter of only 60 μππ are very difficult to handle. For example, such probes are so light and the holes are so small that due to the frictional forces occurring during insertion, it is very difficult to pass the probes through the individual guide plates. It has been shown that guide needles having a thickness of at least 70 μππ, preferably 75 μππ and in particular preferably 80 μππ are much easier to handle, since they are both more stable and heavier and so an adapter can be fitted much easier with these test needles ,

In addition, the two located in a common guide bore 22 probes 19 are arranged substantially narrower to each other than the thinner guided in separate guide holes probes, so that with the inventive arrangement smaller board test points are contacted.

The mutual isolation of the test probes 19 located within a guide bore 22 ensures that the four-wire measurement can be carried out reliably. In the present embodiment, this electrical insulation is accomplished by means of an abrasion-resistant coating.

In the context of the invention, it is also possible to provide an abrasion-resistant plastic film as an insulating layer between the two needles. For grid adapters, there are already test probes that are coated with an electrically insulating plastic. Such conventional plastic coatings ensure satisfactory insulation in a static use of the test pins, in which two Touch needles only briefly and with little force. However, these known plastic coatings are not resistant to abrasion, so that they do not suffice for permanent insulation of guided through a common through-bore portions of the test pins. Appropriately, fiber-reinforced plastic coatings are provided, in particular with nanofiber reinforced plastic coatings that can be applied with a small thickness, yet high strength on the needles. Instead of such a plastic coating also a thin plastic sleeve or plastic film between the two needles can be arranged.

The invention has been explained above with reference to a universal tester with a basic grid and an adapter.

However, the invention is also suitable for a dedicated tester (FIG. 6). Such a more dedicated tester has a Prüflingskontaktierungsplatte 26, in which the test needles 19 are fixed in the pattern of board test points of a circuit board to be tested. Adjacent to the Prüflingskontaktierungsplatte 26 one or more guide plates (not shown) may be provided on the side remote from the circuit board to be tested 6 Prüflingskontaktierungsplatte 26. These guide plates serve to arrange the ends of the test probes pointing away from the printed circuit board to be tested so far apart that a wire 27 can be attached to them by means of soldering. In these guide plates, the probes can be held by friction and / or positive locking. The frictional engagement is made, for example, by sliding two adjacent guide plates one against the other so that the probes are clamped in through holes in the guide plates. A positive connection can be made, for example, by a special geometry of the test probes, such as a thick end, with which the test probes engage positively in a corresponding bore of a guide plate. The test probes are individually soldered to the wires 27, which lead to terminals of the transmitter 2. Several such wires 27 can be combined in cables. According to the invention, in each case a few test probes are arranged in several bores of the Prüflingskontaktierungsplatte to simultaneously contact a common printed circuit test point. These test probes are in turn electrically isolated from each other, for example by one of the above-explained coatings. By arranging at least two electrically insulated test probes in a respective bore of the Prüflingskontaktierungsplatte the same advantages as in the above-mentioned universal tester achieved that on the one hand a very precise four-wire measurement is possible and on the other hand PCBs with a high density of PCB test points reliable are contactable.

FIGS. 5 and 6 each show a parallel tester for a two-sided test of a printed circuit board. Therefore, two Prüflingskontaktierungsplatten are provided, wherein in the universal tester according to Figure 5, the Prüflingskontaktierungsplatte is represented by the respective adapter 7 and its printed circuit board unit 13. Of course, the invention may also be practiced in a parallel tester for unilaterally testing an unpopulated circuit board.

The present invention can be briefly summarized as follows: The present invention relates to an adapter for a parallel tester for testing bare printed circuit boards and a parallel tester for testing bare printed circuit boards.

According to the invention, at least two test probes are arranged in each case in a plurality of guide bores of a test object contacting plate which can be arranged adjacent to a test object, and these test probes are electrically insulated from one another.

This makes it possible to carry out a four-wire measurement in a parallel tester and still provide a high density of contact points.

LIST OF REFERENCE NUMBERS

I basic grid element

2 evaluation device

3 module

4 full grid cassette

5 spring contact pins

6 circuit board

7 adapters

8 guide plate

9 basic grid unit

10 cover plate

I I structural plate

12 retaining plate

13 circuit board unit

14 structural plate

15 guide plate (sample guide plate)

6 cover plate

17 column mechanism

18 organizer pin

19 test needle

20 contact pin

21 thickening

22 pilot hole

23 tip

24 basic body

25 coating

26 Prüflingskontaktierungsplatte

27 wire

28 cables

Claims

claims

1 . Adapter for a parallel tester for testing unpopulated printed circuit boards, comprising

at least one basic grid guide plate (10, 11) and a test piece guide plate (15), wherein the basic grid guide plate (10, 11) has bores arranged in a regular grid whose grid corresponds to a basic grid of a parallel tester,

and the sample guide plate (15) has patterned guide holes (22) corresponding to the pattern of board test points of a printed circuit board (6) to be tested, and

Test probes (19), each having an end portion in one of the holes of the basic grid guide plate (10, 1 1) and with the other end portion in one of the guide bores (22) of the Prüflingsführungsplatte (15) store,

characterized,

in that in each case at least two test needles (19) are arranged in a plurality of guide bores (22) of the test object guide plate (15) and these test probes (19) are insulated from one another.

2. Adapter according to claim 1,

characterized,

in that at least one of the test needles (19) arranged together in guide bores (22) of the test piece plate (15) has an electrically insulating coating (25) which at least covers the abradings located in the region of this guide bore (22). includes the test needle (19), wherein an adjacent thereto tip (23) of the test needle (19) is not coated.

3. Adapter according to claim 2,

characterized,

in that all of the test needles (19) arranged together in guide bores (22) of the test object guide plate (15) are provided with the electrically insulating coating (25).

4. Adapter according to claim 2 or 3,

characterized,

in that the coating (25) is formed from aluminum oxide, titanium oxide or from a carbon coating.

5. Adapter according to one of claims 1 to 4,

characterized,

the test needles (19), which are arranged together in one of the guide bores (22), have a diameter of at least 70 μππ and preferably of at least 75 μππ.

6. Adapter according to one of claims 1 to 5,

characterized,

the diameter of the guide bores (22) in which two test probes (19) are arranged is in the range from 160 μππ to 200 μππ and preferably in the range from 170 μππ to 190 μππ.

7. Adapter according to one of claims 1 to 6,

characterized,

that common in guide holes (22) of the Prüflingsführungsplatte (15) arranged test needles (19) are also arranged together in a bore of a further guide plate (8).

8. Includes parallel tester

a sample contacting plate (26, 15) having patterned holes (22) corresponding to the pattern of circuit board test points of a printed circuit board (6) to be tested, wherein a plurality of pairs of test pins (19) are each formed in a common bore of the sample connection plate (26 , 15) are arranged with one of their end regions.

9. parallel tester according to claim 8,

characterized,

each of the test needles (19) is electrically connected to a unit of an evaluation device (2), wherein two or more test needles (19) are each connected to the same terminal of the evaluation device (2), and the test needles connected to the same connection of the evaluation device each different holes (22) of the Prüflingskontaktierungsplatte (26, 15) are arranged.

10. Parallel tester according to claim 8 or 9,

characterized,

in that at least one of the test probes (19) arranged in pairs in bores (22) of the Prüflingskontaktierungsplatte (26) has an electrically insulating coating (259) which comprises at least the portion of the test needle (19) located in the region of this bore (25), wherein a thereto adjacent tip (23) of the test needle (19) is not coated.

1 1. Parallel tester according to claim 10,

characterized,

in that both of the test probes (19) arranged in pairs in each of one of the bores (22) of the test object contacting plate (26, 15) are provided with the electrically insulating coating (25).

12. Parallel tester according to one of claims 8 to 1 1,

characterized,

in that the parallel tester has a plate-shaped basic screen element (1) on which an adapter (7) is arranged, and the test sample contacting plate is part of the Adapters (7), wherein preferably the plate-shaped basic screen element (1) arranged in a regular grid contact points for contacting a respective test needle (19), and each two or more contact points of the plate-shaped basic grid element (1) by means of a respective conductor track electrically mitein - are connected to each other.

13. parallel tester according to claim 12,

characterized,

in that the adapter (7) is designed according to one of claims 1 to 7, wherein the test piece guide plate (15) of the adapter (7) represents the Prüflingskontaktierungsplatte.

14. Parallel tester according to one of claims 9 to 13,

characterized,

in that the test needles (19) are connected to the evaluation device (2) by means of wires.