Ergonomic, rotatable electronic component testing apparatus

Apparatuses and methods for testing electronic components, such as printed circuit boards, in an ergonomic manner are disclosed. An electronic component testing apparatus comprises a base, a test chamber rotatably mounted to the base, and a heating and cooling unit coupled to the test chamber. The test chamber further includes a chassis defining an enclosure having an opening and at least one test slot accessible through the opening for facilitating operative coupling of an electronic component to the test chamber for testing of the electronic component.

TECHNICAL FIELD

The subject matter disclosed herein relates generally to apparatuses and methods for testing electronic components, and more particularly to providing an ergonomic, rotatable testing apparatus for testing of electronic components such as printed circuit boards.

BACKGROUND ART

For electronic components such as printed circuit boards, environmental stress screening, also commonly referred to as “ageing” or “burn-in” is a part of the usual factory quality control process. Despite the use of high-quality components and assembly procedures, the highly complex nature of electronic components subjects them to occasional manufacturing defects and failures during use. Environmental testing, such as testing variations in temperature, voltage, humidity, etc., is often employed as a means to expedite failure occurrence during production testing of electronic components prior to delivery to end-users or as a way to isolate a given failure that has occurred during the manufacturing process or after use in the field. Because of the high costs associated with such defects and failures in terms of manufacturer warranty obligations and end-user down time, typically a manufacturer will use environmental testing as a way to limit the amount of defective circuit boards leaving the factory as new or being returned to the factory as defective. Therefore, this testing is deemed highly important to manufacturers as part of their customer service and support programs.

While many of the environmental testing steps are completely automated, fault isolation procedures require the intervention of a human operator to transfer the electronic component to the testing chamber, to connect the various data and power cables, to set the environmental parameters in order to reproduce the failure conditions, to probe the electronic component to isolate the failure, and to remove the electronic component from the testing chamber following the fault isolation process. These operator-assisted testing procedures usually include many tedious hours of probing fine pitch electronic components which results in considerable eye and neck strain and can increase the incidence of repetitive motion injuries. Intense competition among manufactures strongly motivates the development and implementation of testing procedures that minimize unit-manufacturing costs. Therefore, ergonomic testing devices that can minimize operator injuries and correspondingly reduce overall manufacturing costs are highly desired.

Moreover, in the usual practice, electronic component testing devices have included several cables that must be connected to and disconnected from the component being tested during each test. After tens or hundreds of connect/disconnect cycles, these cables can develop unpredictable failures, such as open circuits, sporadic intermissions and short circuits. These failures may be related to the cyclic mechanical bending of the cables as welt as the tensile stress induced by pulling on the cable to disconnect the electronic component following testing. These types of failures can be very costly to the manufacturer because failed test cables give erroneous quality control test results leading to a high rate of false rejection and unnecessary rework. It is estimated that the situation due to failing cables can cost manufactures millions of dollars per year in unneeded rework expenses. Accordingly, it is desirable to reduce external cabling required to test electronic components.

Additionally, previous methods of environmental fault isolation testing have been very inefficient to the manufacturer. Previous fault isolation chambers have used externally located heating/cooling units connected to the chamber via external duct work, leading to loss of thermal energy and reduced access to the testing chamber. Also, previous testing chambers have used constant wattage frame heaters for external condensation control. Constant wattage frame heaters have numerous disadvantages, such as wasted power, constant heating of the frame leading to possible hazardous burn conditions, and operator attentiveness required for manually switching on and off the heater strips.

In prior environment test chambers without frame heaters, substantial condensation on chamber surfaces may occur when the chambers are operated for extended periods below the ambient dew point. Such condensation can lead to hazardous electrical conditions.

Therefore, it would be advantageous to employ an ergonomic electronic component testing apparatus that limits the amount of operator motion required for full testing of an electronic component, such as a printed circuit board. Additionally, it would be advantageous to provide an electronic component testing apparatus wherein external heating and cooling ducts and electrical wiring are integrated into the testing unit in order to provide a rotatable unit free from external encumbrances.

DISCLOSURE OF THE INVENTION

The present invention provides an electronic component testing apparatus comprising a base, a test chamber rotatably mounted to the base, and a heating and cooling unit coupled to the test chamber. The test chamber includes a chassis or frame defining an enclosure having at least one opening and at least one test slot accessible through the opening for facilitating operative coupling of an electronic component to the test chamber for testing of the electronic component.

In one implementation, the base includes an upper horizontal frame and a lower horizontal frame, the upper and lower horizontal frames being connected by at least one vertical strut. Wheels may be attached to the lower horizontal frame so that the base is mobile over a surface. The chassis of the test chamber may be a parallelepiped structure including a top wall, a bottom wall, and two pairs of opposing sidewalls. The sidewalls may each define an opening. One or more doors may be removably attached to each sidewall for closing the test chamber during testing. Door retainers may be provided on the vertical struts for holding the doors when they are removed from the sidewalls.

The test chamber may also include a directable dry air purge apparatus, an interior light source, an integrated power strip, and a self-regulating chassis heater for condensation control.

A method of testing electronic components in an ergonomic manner is also disclosed. The method may include providing an electronic component testing apparatus including a base, a test chamber rotatably mounted to the base, and a heating and cooling unit coupled to the test chamber, wherein the test chamber further includes a chassis defining an enclosure having an opening and at least one test slot accessible through the opening for facilitating operative coupling of an electronic component to the test chamber for testing of the electronic component. The method may further include providing an electronic component to be tested, wherein the electronic component has a first side and a second side (also known in the industry as the “solder side” and “component side”). The electronic component is inserted into the test slot in the test chamber where electronic testing is performed while the electronic component is subjected to varying environmental conditions. A technician may rotate the test chamber to electronically or mechanically probe the electronic component before, during, and/or after the testing.

It is therefore an object to provide an ergonomic electronic component testing apparatus and method for limiting the amount of operator motion required for full testing of an electronic component, such as a printed circuit board.

It is another object to provide an ergonomic electronic component testing apparatus and method wherein external heating and cooling ducts and electrical wiring are integrated into the testing unit in order to provide a rotatable unit free from external encumbrances.

Some of the objects of the invention having been stated hereinabove, and which are addressed in whole or in part by the present invention, other objects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.

DETAILED DESCRIPTION OF THE INVENTION

As stated above, the present invention is related to apparatuses and methods for testing of electronic components, such as printed circuit boards. Referring now toFIGS. 1-4, one embodiment of an electronic component testing apparatus of the present invention, generally designated10, includes a base, generally designated20, a test chamber, generally designated40, and a heating and cooling unit, generally designated80. The electronic component to be tested is shown by way of example as printed circuit board12.

In the illustrated example, base20includes an upper horizontal frame22and a lower horizontal frame24, joined together by vertical struts26to form a rigid generally parallelopiped structure. Upper horizontal frame22, lower horizontal frame24, and vertical struts26may be constructed of plastic, metal, such as extruded aluminum, or any other framing material known to those of skill in the art. Plates28may be located on upper horizontal frame22for defining a work surface for a technician and a place for the technician to place tools. A pair of cross members30provides support for plates28and for chamber40. Cross members30are spaced from each other to define a channel32. Channel32facilitates rotational coupling between chamber40and base20, as will be described in detail below.

Base20may further include wheels34or other form of mobile attachments, which are connected to lower horizontal frame24so that base20is mobile over a surface. Vertical struts26of base10may further include one or more door retainers36for storing removable doors associated with the test chamber40.

Test chamber40may be rotatably coupled to base20so that test chamber40may be rotated in a plane parallel to the plane of plates28as indicated by arrows A1and A2. Test chamber40may rotate through any suitable angle to facilitate access to the interior of chamber40from different sides. In one implementation, test chamber may rotate through an angle of 360°. This rotation allows the technician to test printed circuit board12in an extremely ergonomic manner. An exemplary rotational coupling for providing rotation of test chamber40will be described in detail below.

Test chamber40may include a chassis42forming a thermal enclosure of a box-like structure having pairs of opposing sidewalls43including a plurality of openings, such as opening39, though which printed circuit board12can be accessed for testing. In order to provide a thermally maintainable enclosure with access for the technician, the openings39defined by chassis42may be covered by doors44. Doors44are typically double glazed for maximum thermal protection and may be removable from chassis42during periods of non-thermal testing of circuit board12and stored on door retainers36on base20(seeFIG. 2).

Test chamber40further includes a card cage or support45for positioning and supporting circuit board12within the enclosure. Card support45may be any suitable frame structure fixedly attached to chassis42and adapted to slidably receive an edge of circuit board12and support the same during testing.

Referring toFIGS. 2 and 3, at least one test slot46is mounted inside chassis42for facilitating operative coupling of circuit board12to test chamber40for testing of circuit board12. Test slot46is adapted to receive electrical connectors on circuit board12for sending data from disk drives14to circuit board12and back again to detect errors generated by circuit board12. Thus, when electrical connectors on circuit board12are plugged into test slot46, test chamber40is operably connected to circuit board12for testing purposes.

Referring toFIGS. 3 and 6, a directable dry air purge, generally designated48, can also be provided within test chamber40for minimization of condensation within the apparatus and to provide heating or cooling of printed circuit board12during testing. InFIG. 6, directable dry air purge48includes an air outlet50mounted on a base including a rotating member52and a pivoting member54. Rotating member52rotates directable dry air purge48in a direction that is parallel to the plane of a floor of chamber40, as indicated by arrow A3. Pivoting member54pivots in a direction perpendicular to the floor of chamber40as indicated by arrow A4. A regulator56controls air flow through outlet50. Directable air purge48is preferably connected to a dry air source (not shown inFIG. 3orFIG. 6). Thus, using the structure illustrated inFIG. 6, directable air purge48provides a mechanism for directing a stream of dry air to any desired portion of a component under test. Providing a directable stream of air allows a technician to spot heat or spot cool the component being tested and also allows the technician to remove particulate matter, such as dust or loose solder from a component under test with minimal physical exertion.

In order to minimize cables running to test chamber40, an integrated light source58(seeFIGS. 1 and 3) may be provided in the interior of test chamber40for lighting the work space for the technician. Likewise, in order to minimize power cables running to and from test chamber40, an integrated power strip60(seeFIGS. 2 and 4), such as a universal International Electrotechnical Commission (IEC) power strip, may be mounted on the exterior of chassis42so that all electrical devices used within test chamber40can be plugged into power strip60and rotated along with test chamber40. Power strip60provides a globally compatible, AC power connection to testing apparatus10with the requirement of only one power cable being fed to the apparatus.

As discussed hereinabove, when typical thermal testing apparatuses are cooled to temperatures below the ambient dew point (approximately 15° C.) the frames of the thermal testing chambers can experience substantial condensation leading to electrical and other hazards. Referring toFIG. 7, chassis42of test chamber40of the present invention may further include a self-regulating chassis heater72for heating of the chassis. In one example, chassis heater72may comprise self-regulating heat tape commercially available from Raychem Corporation of Menlo Park, Calif. Self-regulating heat tape suitable for use with embodiments of the present invention may include sixteen-gauge tin to copper bus wirers encased in a self-regulating, conductive core. The cable may be covered with a bonded inner jacket and a thermoplastic elastomer outer jacket. An additional tin to copper overbraid may be provided for a low resistance path to ground. The bus wires of the cable may be connected to a power source, such as an AC power source. Exemplary commercially available heat tape suitable for use with embodiments of the present invention is described in heat systems application and design guide H53585, Raychem Corporation, 1999, the disclosure of which is incorporated herein by reference in its entirety.

Self-regulating heat tape is typically used on metal and plastic pipes for freeze protection and low temperature process maintenance. According to the present embodiment, the heat tape of chassis heater72may be embedded internally or on the surface of chassis42. For example, cross members73that form chassis42may include an internal passageway through which chassis heater72may extend in some parts of chassis42. In other parts of chassis42, such as parts where two cross members73meet and their interior passageways do not intersect, chassis heater72may extend outside of cross members73.

In operation, chassis heater72is designed to maintain chassis42at a temperature above the ambient dew point without the need for a thermostat. For example, if chassis42cools, the temperature output of chassis heater72will increase automatically. As the temperature of chassis heater72rises to heat chassis42, the heat output of chassis heater72automatically decreases. This feature of the present invention prevents condensation from forming on the external surfaces of test chamber40and reduces the hazards associated therewith.

Referring back toFIG. 1, heating and cooling unit80is integrally coupled to test chamber40. The integration of heating and cooling unit80into test chamber40eliminates all external ducting to a heating and cooling unit that in the past has encumbered access to the testing apparatus by the technician. In one embodiment, heating and cooling unit80is mounted to the top surface of test chamber40so that heated or cooled air is blown into test chamber40in order to create the thermal condition set by the technician. In an alternate embodiment, heating and cooling unit80may be mounted to any of the side surfaces or to the bottom surface of test chamber40without departing from the scope of the invention. The temperature that heating and cooling unit80maintains inside test chamber40is programmed in and maintained by thermostat82which is mounted to heating and cooling unit80. Heating and cooling unit80can be any standard commercial unit, such as Model No. HB160926032ER made by APW, Ltd. of Waukesha, Wis., and thermostat82can be any typical commercial thermostat, such as Model Number A419 commercially available from Johnson Controls Corporation of Milwaukee, Wis.

FIG. 8is an exploded view of heating and cooling unit80and chassis42. InFIG. 8, chassis42includes an upper surface84that includes an air intake aperture86and an air outflow aperture88that match with corresponding apertures90and92, respectively, on the lower surface of heating and cooling apparatus80. Because heating and cooling unit80is mounted to chassis42without external duct work, 360° rotation of chassis42can be easily achieved without disengaging heating and cooling apparatus80.

As stated above, chassis42is preferably rotatably mounted to base20. In one example, as shown inFIG. 2and as shown in more detail inFIG. 5, chassis42may be rotatably mounted to base20using a rotational coupling, such as an axle and hub assembly100, of the same type used to mount wheels to rolling vehicles. InFIG. 5, chassis42is fixedly attached to a flange102of a hub assembly104. Hub assembly104includes roller bearings that allow hub and consequently chassis42to rotate about an axle106. Axle106is fixably attached to cross members30of base20via sprocket108. Because axle106is fixably attached to base20and chassis42is rotatably attached to axle106, chassis42is capable of rotating with respect to base20. Angle brackets110may be mounted on opposing sides of flange102to stabilize chassis42. Although in the example illustrated inFIG. 5, hub assembly104is fixedly attached to chassis42and axle106is fixedly attached to base20, the present invention is not limited to such an embodiment. In an alternate embodiment, hub assembly104may be fixedly attached to base20and axle106may be fixedly attached to chassis42.

In design and operation, the integrated heating and cooling unit and electrical aspects of the testing apparatus, along with the rotation ability of the test chamber allows optimal access to both sides of the printed circuit board or other electronic component by the testing technician without the technician having to move from their posted position. In operation, the technician will first approach testing apparatus10and establish a position that the technician will maintain throughout the testing procedure. If the thermal testing of circuit board12is not required, the technician may remove doors44and place them upon door supports36(FIG. 2) so that testing chamber40is less encumbered by doors44. Otherwise, doors44will remain in place for thermal environment stabilization.

Test chamber40is then rotated to a position so that the technician can insert circuit board12into test slot46so that the circuit board12is operatively coupled to test chamber40for testing. It is envisioned that test chamber40may include a plurality of test slots46and therefore several circuit boards12may be tested simultaneously depending on the parameter to be tested and the speed at which the technician must perform the testing procedure.

If thermal testing is required, the technician will then shut all doors44and will set thermostat82on the desired temperature at which circuit board12should be tested, so that heating and cooling unit80begins to heat or cool test chamber40to the desired temperature.

Once circuit board12has been properly seated in test slot46and the proper test temperature has been reached inside test chamber40(if applicable), the requisite testing data sequence will then be established by the technician so that data begins to flow from drives14to circuit board12. When a fault is indicated, the technician will open doors44(if applicable) and by using probes or other electronic testing tools can test one side of circuit board12for the applicable data information or fault location. Once testing on this side of circuit board12is complete, the technician can easily rotate test chamber40so that additional probing can be performed on the other side of circuit board12.

During testing, if circuit board12requires spot heating or cooling, the technician can direct dry air purge48to a specific position so as to isolate an air stream directly to the component needing the additional air flow. Additionally, as discussed hereinabove, if the temperature within test chamber40should cool down below the ambient dew point during testing, self regulating chassis heater72will automatically turn on, thus warming chassis42and reducing the potential for condensation to form on the unit.

Once testing is complete on circuit board12, the technician will then rotate test chamber40to a position so that circuit board12can be removed from test slot46thereby rendering the test cycle complete. At this point, another test cycle can be commenced or testing apparatus10may be moved from its current position to a storage area for storage.

It will be understood that various details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation, as the invention is defined by the claims as set forth hereinafter.