CN1079536C - Method and device for testing of electronic components - Google Patents

Abstract

A test assembly for use in testing electronic components, preferably surface mount IC-circuit components, includes a carrier (4) by means of which a component (2) is picked-up and brought to and held against the conductors (6) on a printed circuit board (5). The printed circuit board (5) includes at least one cavity (9) underneath the contact conductors (6) in the region where the component (2) is to be held, such as to render the conductors resilient. Pressure pads (7) are placed in the cavity (9) between the bottom of the cavity and the contact conductors (6) such as to regulate the resilience of the conductors (6).

Description

Method and device for measuring electronic components

                    

The present invention relates to a method, a device and a circuit card for measuring electronic components such as IC circuits and especially surface mount components.

Background technique

At present, electronic components such as IC circuits are electronically tested by means of specially designed contactors, and the integrated circuits are temporarily put into the contactors during testing without soldering. The development of testing based on small, fast surface mount components has not grown to meet the new requirements, resulting in greater uncertainty in the testing of the components, which leads to an unnecessarily high number of components being scrapped on the production line. When measuring dynamic parameters such as Wuick function tests, transit delays or high frequency oscillations, the true nature of the component is often offset by the mechanical construction of the test socket. Deviations in the measurement results often occur due to stray capacitances of the test sockets in the measurement loop. When measuring static parameters, measuring the internal resistance and contact resistance of the socket also leads to distortion of the measurement results.

US patent 4 754 555 describes a device for testing the coplanarity of IC capsules. More specifically, the apparatus is used to determine that the legs of the IC packages have the same length. The IC package is pressure-fitted into a socket assembly in the device. The socket assembly contains elastic means corresponding to the legs of the IC circuit, each elastic means contacts one of the legs when pressure is applied on the IC circuit, if the legs are long enough. The elastic means are in contact with a so-called PC card containing control logic which indicates when contact is made between the legs and the PC card. This equipment is not intended to be used to test the function of electronic circuits. The equipment is complex and expensive due to the large number of components.

US patent 4 866 374 describes a so-called contactor assembly. This contactor is mounted on a circuit card and connects a surface mount circuit device under test (DUT) to the circuit card. The assembly is also more complex and expensive due to the higher number of components involved.

Test sockets of similar construction to the one shown in Figure 1 are currently available from several different suppliers. The required contact pressure to the conductor 1 on the element 2 is usually achieved by means of the elastic portion 3, similar to that shown in FIG. 1 . The resilient portion is stamped, cut or etched from a resilient metallic material such as phosphor bronze, beryllium copper or similar. To obtain an effective connection and a suitable contact pressure, it is necessary for the configuration to be relatively geometrically extended. The elastic portions are then arranged adjacent to each other at a distance corresponding to the connection on the element. As the size of such components continues to decrease, the elastic parts are placed closer together, causing undesired stray capacitance between conductors to occur.

None of the above publications teach measuring circuit elements directly on the circuit card.

DE-C1-3 636 361 describes a device for measuring the function of surface-mounted circuits directly on the circuit card. The device is adapted to be inserted into a heating cabinet and includes a circuit card, a receiving plate with recesses corresponding to the circuits and a pressure plate with elastic elements corresponding to the circuits. The card and board include suitable guide and locking means to guide and secure the card and board together. In the test circuit, it is necessary to collect and place the circuit in the notch, after which the circuit card, the circuit containing plate and the pressure plate are put together, aligned with each other and locked together, and the circuit containing plate is placed between the circuit card and the pressure plate, The circuit is thus pressed against the circuit card by the elastic element. Although the device is simple and inexpensive, it contains an unnecessarily large number of components. Test methods applied outside the heated chamber also unnecessarily contain a large number of steps.

There is no document known in the art describing a circuit card specially designed for testing purposes which avoids the use of sockets for the components to be tested. Nor does it describe a method for quickly and easily testing components on a circuit card.

Invention Summary

The purpose of the present invention is to improve the accuracy of measurement compared with the prior art when testing electronic components on a circuit card.

Another object is to provide an electronic component testing device with fewer components.

These objects are achieved by means of a device comprising a component carrier which receives the component and holds the component against a circuit card to be tested which comprises a cavity below the contact conductors in the area of holding the component.

Yet another object is to provide a circuit card for testing electronic components that does not require contact sockets.

This object is achieved by a test circuit card comprising a cavity below the contact conductors in the area where the component is to be held.

Another object of the present invention is to provide a simple and quick method for detecting electronic components on a circuit card to be tested.

This object is achieved by a method in which the components are collected, sent to a printed circuit card for testing and directly against the card during the test.

These and other objects and advantages provided by the present invention will become apparent from the following description of preferred embodiments of the present invention.

Brief description of attached drawings

Fig. 1 is the sectional view of aforementioned known test socket;

Figure 2 is a front sectional view of the inventive device according to the first preferred embodiment;

Figure 3 is a front sectional view of a second preferred embodiment of the inventive device;

Fig. 4 is a sectional view of the device shown in Fig. 3;

FIG. 5 is a view of the components of the device in FIG. 4 from above.

Detailed Description of Preferred Embodiments

Figure 2 shows a first preferred embodiment of the invention for testing electronic components 2, preferably surface mount IC components, containing a carrier 4 and a circuit card 5 for testing, a so-called printed circuit board (PCB). ) or motherboard. Only a part of the motherboard 5 is shown in the figure, that is, the place where the device under test (DUT) 2 is placed. Conductors 6 are drawn on the motherboard 5 (only part of two conductors are shown), these conductors 6 usually consist of copper skin on the motherboard. The cavities 9 are placed on the motherboard 5 in the areas where the components 2 are accommodated. The surface of the chamber 9 is configured according to the element 2 to be tested, including its legs. The part of the conductor 6 which is connected to the leg of the element 2 extends over the edge of the cavity 9 . Part of the circuit board material remains under the conductor 6 to be contacted. In the preferred embodiment, two pressure plates 7 extend along opposite sides of the cavity 9 , wherein each pressure plate is placed between the bottom of the cavity 9 and the conductor 6 .

The cavity 9 is provided in the motherboard 5 to provide elasticity for the conductor 6 . Pressing plate 7 can be made by rubber, plastics, insulating material etc., and effect is that the stress in the conductor 6 is controlled, and it can save when needed.

The structure of the motherboard 5 is such that the component 2 can be directly placed on the motherboard 5 when testing the component. When testing a component, the carrier 4 takes the component 2 from the component storage (not shown), moves the component 2 onto the motherboard 5 and holds the component 2 against the motherboard 5 on the cavity 9, the legs of the component 2 are in contact with the The conductors 6 are in direct contact. This can be achieved by utilizing the elasticity of the conductor 6 .

The carrier 4 contains a cavity 11 cooperating with the body region of the component 2, and border portions adjacent to the legs of the component 2, for pressing the component 2 against the motherboard 5, for example with a uniform pressure.

The structure of the motherboard 5 provides greater test accuracy when testing the component 2 than when testing in a test socket. The problem of stray capacitance encountered with test sockets is avoided, the number of electrical connections is reduced, so that fewer components are scrapped during testing, and the HF characteristics are improved.

Figure 3 shows another embodiment of the device, in which the carriage 4 contains a suction cup 8 for picking up, moving and holding the components. Naturally, the carriage 4 could contain some other form of means to perform the same function, such as pneumatic means or other forms of clamping means.

Figure 4 shows a second embodiment of the test assembly in which the printed circuit board contains slots 10 through the cavities 9 on each side of each conductor 6 so that the conductors have their respective elasticity.

Finally, FIG. 5 illustrates the bracket 4 secured to a part of the printed circuit board 5 , where the board 5 contains conductors on both sides of the cavity 9 . The element 2 and its legs are also shown in the figure, although the legs are covered by the bracket 4 . Naturally, the board 5 can be constructed so that the legs of the circuit are on all 4 sides, the shape delimited by the surfaces of the cavity 9 depending only on the shape of the element 2 .

The preferred embodiment comprises a large chamber 9 whose surface covers the entire component 2 to be tested. However, in addition to targeting different element types, the cavity can be varied in several ways. For example, a separate cavity may be provided for a leg under each conductor or a group of legs under several conductors parallel to each other. The key feature is to provide a cavity under each conductor for each leg of the element to provide the desired elasticity.

The bracket is suitable for mounting on robots, especially pick and place robots, to ensure that the testing process is completed quickly and efficiently.

Claims (6)

1. An electronic component testing assembly, especially suitable for surface mount components, comprising a printed circuit board (5) and a component carrier (4) for receiving the component (2) and placing and holding it on On a printed circuit board (5), characterized in that the printed circuit board (5) comprises at least one cavity (9) located below the contact conductor (6) in the area of the fixed component (2) under test , in order to provide elasticity to the conductor. 2. Test assembly according to claim 1, characterized in that between the bottom of the cavity (9) and the one or more contact conductors (6) there is a pressure plate (7) for adjusting the elasticity of the conductors. 3. A test assembly according to claim 1 or 2, characterized in that there are slots (10) through the cavity (9) on both sides of each contact conductor (6) in order to provide elasticity to the conductor respectively. 4. A printed circuit board (5) for testing electronic components, especially surface mount components, characterized in that under the contact conductor (6) on the circuit board in the area where the electronic component (2) to be tested is to be placed There is at least one cavity (9). 5. The printed circuit board (5) according to claim 4, characterized in that a pressure plate (7) is placed between the bottom of the cavity (9) and one or more contact conductors (6) for adjusting the elasticity. 6. A printed circuit board according to claim 4 or 5, characterized in that there are grooves (10) through the cavity (9) on both sides of each conductor (6) in order to provide elasticity to each conductor respectively.

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