Probe system for QFP IC device test tools

Abstract

The present disclosure provides a probe system for a QFP integrated circuit device test tool. The present disclosure describes an automated high-speed test solution for a square flat package device package that enables connection between a test instrument and an integrated circuit under test. A test probe geometry is provided that provides high repeatability and reliability connection suitable for use with consumer-grade QFP devices, as well as ease of maintenance. In some embodiments, the probe tip end is chisel-shaped. The probe can be slightly tilted relative to the longitudinal axis of the probe holding block.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to pending U.S. Provisional Application No. 63 / 182,733 (Attorney Docket No. ES-2102-P), filed on April 30, 2021, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to systems and methods for reliable testing tools for packaged integrated circuit (IC) devices. In particular, improved probe configurations and accessories for quad flat pack IC device testing tools are provided. Background Art

[0004] Test socket solutions for packaged IC devices suffer from deviations and inconsistencies in the ability of contacts to connect and therefore in electrical connectivity due to wear and tear stresses during the life cycle. These unavoidable effects continue to result in invalid test failures, higher retest rates, longer test tool downtime, and higher IC device test costs. High-performance packaging for integrated circuits with a large number of connection structures requires densely packed contacts, and in many cases, these contacts are located in a grid array at one or both of the top and bottom of the package.

[0005] While most signal connections can tolerate some degradation in series resistance due to wear of the probe assembly, ground connections are less tolerant of introduced series resistance, as ground currents can cause crosstalk between signal connections and signal distortion. The effect of resistive elements in signal distortion is fairly broadband and more or less independent of frequency; skin effect, in which current is not located in the bulk of the conductor but in a thin layer at the surface, also contributes to some extent, but for small signals, skin effect can generally be considered a minor concern. Test fixtures are used for characterization and qualification and are therefore expected to produce reliable and repeatable results for any of the device under test (DUT) parameters in a single run. This is in contrast to the use of the same DUT in a real application, where the external parameters of the device (such as voltage and current) are fixed during the prototyping phase, after which the only significant variable is the device itself. Where a precision contact array is provided, probes with sharp tips can be used to generate sufficient pressure to penetrate oxides or coatings that may be present in the contact area. By setting the probe at a shallow angle to the part being measured, displacement of the probe contact point also results in lateral movement. This added scraping action improves the quality of contact, but at the expense of some wear on the probe element itself.

[0006] The contact probes of test tools used to test IC devices are usually made of conductive metals and metal alloys, such as beryllium copper (BeCu), brass and steel alloys. Depending on the specific application, these contact probes can be coated and / or plated with suitable conductive materials, such as gold, iridium, nickel, palladium and cobalt, to provide low resistance that is not affected by oxidation (especially at higher frequencies where the skin effect dominates the current flow), and then passivated with a suitable insulating layer to avoid short circuits in the fixture itself.

[0007] However, during repeated testing of IC devices, for example, after 100,000 test cycles, these contact probes of the test tool will continue to be affected by repeated connection and disconnection to the IC device under test. As a result, the contact probes often suffer from contact degradation due to the peeling of the plated conductive layer, metal oxidation and foreign matter adhesion, resulting in substantial contact capability degradation. Although the introduction of resistance in the circuit can be tolerated by signal connections when small currents are involved, areas of high current (such as shared ground connections) will present serious problems. In addition to introducing resistance changes in the current path, these physical changes will also cause the reactance elements of the circuit to change, which will result in a modified input signal that varies with frequency.

[0008] Furthermore, after repeated, sequential testing of IC devices as described above, the penetration capability of the test tool contact probes is also affected by the substantial loss of inherent compliant forces generated by the spring or resilient element contained by the corresponding contact probe body or barrel. This problem is exacerbated as the IC device contact pitch size decreases, and for commercial quality devices manufactured with leads located at the edge of the package (e.g., quad flat packs), the variability in contact location presents a new type of problem beyond the need to penetrate the oxide layer on the lead surface.

[0009] It is apparent that there is a pressing need to improve the performance of contact probes of IC test tools intended for use with devices having a high density of pins located at the edge of the package after repeated test cycles. This improved probe performance enables more reliable testing of ever-shrinking IC devices for longer periods of time without any unnecessary downtime of the IC test tool associated with failure or substantial degradation of the contact probes. Summary of the invention

[0010] To achieve the above objectives, according to the present invention, a system and method for reliably testing a packaged high-speed integrated circuit (IC) device having a high pin density at the edge of the package is provided.

[0011] In one embodiment, a test probe assembly is configured for testing a packaged quad flat package (QFP) integrated circuit (IC) device. The test probe assembly includes a plurality of probes or probes, a terminal pad adapter, and a docking assembly, wherein the terminal pad adapter allows the test probe or probe located on one side to be connected to the test instrument, and the docking assembly ensures repeatable alignment of the device under test. The docking assembly also includes a pressure pad that provides support for the pins of the QFP device to prevent the pins from being deformed by displacement caused by the contact pressure of the probe. The plurality of probes are configured to repeatedly maintain reliable electrical contact with corresponding plurality of contacts on the device under test (DUT) when under compliance. The transfer pad provides mechanical and electrical coupling with the plurality of probes, and also provides endpoints for connecting to cables from various test instruments to send and receive signals from the DUT. The transfer pad may also include a reactive element containing a section of a transmission line to allow proper matching or elimination of some or all of the parasitic reactance introduced by the test fixture.

[0012] One aspect of the present disclosure provides a test probe assembly for testing a packaged integrated circuit (IC) device under test (DUT), the test probe assembly comprising: a probe holder having a plurality of probe holding cavities; a plurality of compressible probes configured to repeatedly maintain reliable electrical contact with a corresponding plurality of packaged integrated circuit device under test contacts when under a compliant force, each of the probes having a probe barrel, and oppositely extending upper and lower probe tips, wherein the probe barrel is contained within a corresponding one of the plurality of probe holding cavities, wherein at least one of the oppositely extending upper and lower probe tips of each of the probes is capable of being pressed into the probe barrel; and wherein each of the upper probe tips comprises an upper section having a rectangular cross-section and a chisel-shaped tip end, wherein each of the probe holding cavities comprises a corresponding rectangular cross-section hole to enable the chisel-shaped tip end to protrude from a top surface of the probe holder.

[0013] In one embodiment, the chisel tip is rounded at its distal end.

[0014] In one embodiment, the chisel tip is chamfered at its distal end.

[0015] In one embodiment, the chisel-shaped tip distal end has an area substantially parallel to a contact plane of a lead of the packaged integrated circuit device under test.

[0016] In one embodiment, the lower probe tip is tapered, wherein the test probe assembly includes a lower block having a plurality of cylindrical channels for securing the lower probe tip.

[0017] In one embodiment, the plurality of probe holding cavities are angled.

[0018] In one embodiment, a first subset of the plurality of probe holding cavities is counter-inclined relative to a second subset of the plurality of probe holding cavities.

[0019] In one embodiment, the chisel-shaped tip ends of a first subset of the plurality of probes are configured to be arranged at 90 degrees relative to the chisel-shaped tip ends of a second subset of the plurality of probes.

[0020] It should be noted that the various features of the present invention described above can be implemented individually or in combination. These and other features of the present invention will be described in more detail in the following detailed description of the present invention in conjunction with the following drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order that the present invention may be more clearly ascertained, some embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0022] Figure 1 is a simplified diagram showing the components of a high-density QFP test probe according to one embodiment of the present invention, wherein the components of the high-density QFP test probe are greatly enlarged for ease of viewing;

[0023] Figure 2A and Figure 2B Two embodiments of details of the outside of the probe are shown, with emphasis on the portion used to contact the QFP connection pins;

[0024] Figure 3A An example test setup is shown in which contact points of an interposer board, a portion of a probe holding block, and one probe in contact with one of the connection pins of a QFP device are shown;

[0025] Figure 3B An enlarged view showing the connection between the probe element and the connection pins, the enlarged view not showing the probe holding block to avoid obscuring details;

[0026] Figure 3C use Figure 3B A simplified version of FIG. 1 shows a cross-sectional view of a probe assembly positioned in a probe holding block;

[0027] Figure 4A The probe element is shown protruding through the surface of the probe holding block without showing the device under test;

[0028] Figure 4B Shows Figure 4A sectional form for illustrating how the probe assembly is positioned within the probe holding block; and

[0029] Figure 5 Elements of a device holder that positions and supports a device under test relative to a probe assembly are shown. DETAILED DESCRIPTION

[0030] The present invention will now be described in detail with reference to several embodiments shown in the accompanying drawings. In the following description, many specific details are set forth to provide a thorough understanding of embodiments of the present invention. However, it is apparent to those skilled in the art that embodiments may be practiced without some or all of these specific details. In other cases, in order to avoid unnecessarily confusing the present invention, well-known process steps and / or structures are not described in detail. The features and advantages of the embodiments may be better understood with reference to the following drawings and discussion.

[0031] By combining the following description of (one or more) drawings, the aspects, features and advantages of the exemplary embodiments of the present invention will be better understood. It should be clear to those skilled in the art that the embodiments described in the present invention provided here are only exemplary and non-restrictive, and are presented only by way of example. Unless otherwise expressly stated, all features disclosed in this specification can be replaced by alternative features for the same or similar purpose. Therefore, many other embodiments of its modification are expected to fall within the scope of the present invention as defined herein and its equivalents. Therefore, the use of absolute and / or sequential terms, such as "will", "will not", "should", "should not", "must", "must not", "first", "initially", "next", "subsequently", "before", "after", "last" and "finally" does not mean to limit the scope of the present invention, because the embodiments disclosed here are merely exemplary.

[0032] The present invention relates to a system and method for an improved contact probe for a reliable test tool for packaged integrated circuit (IC) devices that use edge mounted connection pins according to a square flat package layout. Devices of this type are intended for high density or high pin count circuits that are intended for batch assembly using conventional soldering techniques commonly used to manufacture consumer electronic devices. Historically, early integrated circuits were packaged using a row of pins with a defined pitch of 0.1 inches, and although there are examples of "single in-line" packaged devices for passive components, active devices are more commonly packaged in "dual in-line" packages. The physical size of the packaged device depends on the complexity of the device in terms of the number of required input connections, output connections, and power connections. As the number of pins increases, the circuit board area required for such packaged devices is forced to change to use not only two edges of the package, but also two ends. Coupled with the task of minimizing area, the result is a four-sided, approximately square package with pins on each edge of the package. Common sizes range from 32QFP with 8 pins on each edge to 304QFP with 76 pins on each edge. The distance between pin centers is typically between 0.4 mm and 1 mm (approximately from 0.015 in. to 0.040 in.), and of course, as this size decreases, the pins become more fragile and more susceptible to deformation. One operating limitation of the smaller size is the tendency for solder bridges to form during soldering, although this is an acceptably small risk for modern surface mount technology. Automated testing requires that the test instrumentation does not cause damage to the pin geometry, so steps must be taken to ensure that probe pressure is offset by an appropriate support mechanism for the pins.

[0033] Probes of the type described herein typically allow a complex set of test instruments to be connected to an integrated circuit having a large number of connection structures: the test instrument often includes a power supply, a signal source or generator, a data collection instrument, and an analysis instrument. The test instrument can be hardwired to any test probe assembly, but modern implementations of test instruments conventionally terminate the instrument with a terminal piece or terminal board, a transfer pad, which is then attached to the assembly containing the probe. In this way, one end of the probe that makes up the probe assembly is coupled to the terminal board, while the other end is prepared for connection to the device under test. One aspect that needs to be noted is that automated test instruments are intended to test a large number of devices, so the need for repeated connections and disconnections with high repeatability and reliability is a fundamental consideration in the design.

[0034] Repeated connections and disconnections result in wear of the probe assemblies associated with the probe station, with the result of such wear being variations in the quality of the connection to the DUT. Deterioration of the test fixture, whether mechanical or electrical, is problematic because the resulting inappropriate rejection of the component being tested can have serious cost implications, particularly with modern high-density technology. Of course, the actual pin layout and distribution of the pin density is determined by the individual component parts to be tested. By constructing the terminal board of the test instrument as separate from the probe assembly containing the contact probes, it is possible to efficiently replace the probe assembly when the pins begin to wear or according to a planned maintenance schedule, thereby avoiding unplanned production losses with respect to the test instrument; it is noteworthy that the connection between the probe assembly and the transfer pad is only changed when a new probe assembly is positioned as a replacement for the old worn component. As described above, it is an object of the present invention to provide a mechanism for improving the performance of a test fixture assembly including contact probes and their mounting fixtures.

[0035] To facilitate discussion, Figure 1 1 is a side view of an embodiment of a test probe intended for use with a QFP package. The probe 100 includes a plurality of components, wherein two contact probes 115 and 120 are mounted within a cylindrical housing 110, and a spring (not shown) compresses at least one of the two contact probes. The contact probe 115 is a cylindrical probe that tapers to a relatively sharp point. The probe 115 slides into the housing 110 against spring pressure and is intended to contact an adapter board having a plurality of contact pads that are connected to endpoints connected to an external test instrument. The probe is typically confined within the housing by a curled end that allows the probe to move but is formed as an orifice that is small enough to not allow the probe to escape.

[0036] At the other end of the housing, the contact probe 120 is also cylindrical, and the contact probe 120 is inserted into the housing 110 and is imprisoned in the housing 110. However, the contact tip of the contact probe 120 is deformed to form a rectangular cross-section as shown in the cross-sectional view BB-BB. The contact tip can be machined or stamped to form a rectangular cross-section, and its purpose will be clear in the later part of this article. Unlike the contact probe 115, which tapers to a point, the probe 120 has a different geometric structure and is designed to ensure that the device under test is properly connected to the test circuit.

[0037] As with consumer devices, the connection pins on the quad flat package are intended for soldering, so the lead frame is tinned with a suitable material that is easy to solder using conventional techniques. Typically, low-cost, easy-to-solder materials tend to oxidize very quickly, so the typical soldering process involves the application of a flux (usually integrated with the solder paste or solder wire), which chemically removes the oxides when heated, thereby ensuring a good quality, reliable solder bond. The test instrument does not have a wet chemical step, so a good quality connection must be made entirely by mechanical action. The probe system meets this requirement by setting the probe at a small angle to the expected contact point, and when the device under test contacts the probe tip, these probe tips are compressed into the retaining sleeve of the probe tip under spring pressure. Because these probe tips are at a certain angle to the vertical, the compression in the vertical direction also produces mechanical movement in the horizontal direction, which causes a scraping action on the lead or contact of the device under test. The detail 120 of the "chisel-shaped" probe is shown in more detail as circled by the enlarged figure AA, which shows the rounded tip. There are a variety of possible configurations that maximize the reliability of the connection while keeping the wear of the contact probes in the probe assembly within reasonable limits. This wear is unavoidable due to mechanical friction at the contact area itself, but a good service life can be achieved without sacrificing reliability.

[0038] In this embodiment, the "chisel-shaped" end of the probe tip shown at AA may be rounded, meaning that the contact area is formally a tangent to the curve. It can be seen that, in practice, wear will erode this contact tangent to an area, but as this wear continues, the pressure at the contact point will decrease until contact becomes less reliable. To address this issue, a second implementation modifies the tip of the probe to have a flat area parallel to the tangent. The latter has the advantage of avoiding the rather rapid wear rate exhibited by relatively high pressures in the early stages of use, thereby improving repeatability. It is apparent that the tangent is formally parallel to the adapter plate that contacts the opposite end of the probe assembly.

[0039] Figure 2A Shows Figure 1Two perspective views 200A of the probe probe 100 of the embodiment of the present invention. A cylindrical housing 210 holds two contact probes 215 and 220. The ends of the probes located within the housing are separated by springs that allow at least one of the two probes to slide into the housing and simultaneously provide force to hold them firmly against the connection points on the adapter board and the contact leads of the device under test. The cylindrical housing is conductive and cooperates with the spring, which is also conductive, to ensure that there is always good electrical contact between the two contact probes 215 and 220. To help achieve this, the inner surface of the cylindrical housing and the outer surface of the contact probes can be coated with a suitable material to resist oxidation or other damage. Gold or palladium are examples of such coating materials. If a hard, wear-resistant surface is required, nickel can be used; in one implementation, the component is nickel-plated and a fine gold or palladium plating is applied to its tip.

[0040] In some embodiments, the outer surface of the cylindrical housing is passivated so that the housing of the probe is insulated from a holder that secures the probe relative to a test fixture. Anodizing is an example of a passivation process, but other coating techniques may be used; the housing of the probe does not move during operation and there is no wear on the outer surface between the probe and the holder that supports the plurality of probes themselves.

[0041] exist Figure 2A In the illustrated embodiment, the tip 225 of the probe 220 can be seen to have a rectangular shape and is also shown as having a smooth, curved end. The rectangular shape is simple to manufacture and resists rotation when engaged with the retaining housing into which all probe pins will be inserted so that the alignment of the tip can be determined at all times. Typically, the tip 225 of the probe 220 is plated in a similar manner to the rest of the probe for purposes of durability and reliability of connection quality. Wear on the QFP leads is irrelevant because the material they are plated with is very soft and the soldering process when the component is built onto the circuit board eliminates the effects of any wear.

[0042] Reference now Figure 2B In another embodiment, the tip 285 of the probe 220 can be seen to have a rectangular shape and is shown with an alternative chamfered tip end profile. The rectangular shape is simple to manufacture and resists rotation when engaged with the retaining housing into which all probe tips will be inserted so that the alignment of the tip can be consistently determined. Typically, the probe tip 285 is plated in a similar manner to the rest of the probe for purposes of durability and reliability of connection quality.

[0043] Other probe tip profiles (not shown) are also contemplated within the spirit of the present invention. For example, the probe tip may be shaped to have tapered lands approximately parallel to the upper and lower surfaces of a holding block to provide an angular displacement that ensures highly repeatable sliding and / or scraping contact when the device under test is placed on a fixture that supports a collection of probes used in a test fixture.

[0044] Now go to Figure 3A , a typical square flat package integrated circuit is shown at 310. QFP details are freely available from any manufacturer, and the precise mechanical specifications form a normal part of the public version of the data sheet. Connecting leads 320 or pins for coupling to the integrated circuit are located on each side of the package, which is typically square in form with the same number of pins along each edge. It should be noted that the package can also be rectangular with one pair of opposite sides having a certain number of pins and the remaining pair of opposite sides having another number of pins. In this figure, feature 315 is an identification feature used to ensure correct placement of the package; typically a depression, bump or notch is used to indicate the first pin in the pin numbering sequence of the packaged device, and in an automatic test setup, this feature is detected to ensure correct insertion direction.

[0045] An adapter circuit board 305 is typically used to connect the test instrument to the test fixture and to properly attach the miscellaneous cables to the probes that will be used to contact the device to be tested. This allows for high quality cable terminations, including strain relief, and allows any termination components to be assembled to ensure proper matching of critical signals, such as resistors or reactance components, such as high frequency signals or fast switching signals. Contact points 325 are typically located on the adapter board, and the contact points 325 are connected to the cables from the test instrument. In one implementation, these contact points are positioned so as to correspond to the connecting leads 320 or pins at the QFP device under test. The probe holder 330 is machined to accommodate the probe and position the probe to contact the adapter contact point 325 at the lower surface of the probe holder 330. One hole 340c of a plurality of probe holes 340c...340d located on the upper surface of the probe holder 330 allows the rectangular end section 335c of the probe 220 to protrude from the probe holder 330.

[0046] Figure 3BThe position of an exemplary probe is shown (depicted in a suspended manner without showing the probe holder), and the connection between the contact point 215 on the adapter board, the cylindrical housing 210 of the probe and the upper contact 220 of the probe to the protruding tip 225 and then to the connecting lead 320 of the device under test is shown. The angle to the normal is set by the geometry of the holder (not shown), and the contact point between the tip 225 and the connecting lead 320 is shown as a smooth curve for simplicity in this figure. It should be understood that the tip can have a predetermined starting area plane that is cut so as to make contact with the adapter circuit board 305 or Figure 3C The upper surface plane 332 of the probe is approximately parallel. It will be appreciated that by using a wide contact line or face, some misalignment of the connecting lead 320 and the tip 225 of the probe can be tolerated. If a point were to be used, misalignment of the connecting lead 320 by half the width would result in lateral displacement and deformation of the connecting lead, which could render the component unusable in production due to the risk of solder shorts during assembly.

[0047] Go to Figure 3C , Figure 3C 3 is a detailed cross-sectional view of an exemplary probe 210 inserted into a machined pocket 355 in a holder main block 330. The probe 210 is inserted into the main block 330 so that the rectangular section 225 of the upper contact probe 220 engages in the machined approximately rectangular hole 340c. The machined surfaces of the exemplary pocket and hole may be passivated by a hard anodized layer that provides electrical insulation between the holder main block 330 and the individual probes (e.g., probe 210). After all required probes are inserted into the holder main block, the lower block 350 is attached so that the probe probes remain captive in the holder assembly. The holder block with the mounted probes is then secured to the adapter plate so that the lower contact point of the probe contacts the designated contact pad 325 printed on the adapter plate 305, thereby making a connection to the cable to the test instrument. For clarity, the spring that separates the two contact probes of the probe and provides the required contact compliance is not shown.

[0048] Figure 4A The ends 335c, 335d of the two probe probe tips are shown protruding through corresponding holes 340c, 340d located in the upper surface plane 332 of the holder block 330. The figure shows the change of probe orientation at the corner of the holder, where there is a 90° rotation between the rectangular holes 340c, 340d in the upper surface of the holder block 330. Figure 4B A row of three holes 340a, 340b, 340c is shown, including a cross-sectional view showing hole 340c receiving probe tip 225. The spring or other resilient element between the ends of the two contact probes is again omitted to avoid confusion.

[0049] Test probe probes suitable for use in the present application are highly miniaturized, typically less than 0.25 inches in length when fully extended and less than 0.020 inches in outer diameter in the configuration shown in the present application. In a preferred implementation, the test probes are arranged in four single rows corresponding to the arrangement of the connecting leads of the QFP device. In a second implementation, the probes are arranged in two slightly offset rows on each of the four sides, alternating the probes so that the odd-numbered probes are in one row and the even-numbered probes are in another row. This latter implementation allows for slightly larger probe spacing, but requires a more complex holding block manufacturing process.

[0050] Figure 5 A design of a device handler test fixture assembly 500 is shown, which is used to place a device under test (DUT) in a test fixture for testing. The functions that the assembly must perform include collection and retention of the DUT, alignment of the DUT to prevent the DUT from rotating from the correct position, alignment of the DUT to ensure proper placement of the connecting leads relative to the probes used for testing, and proper support of these connecting leads to ensure that the lead alignment arrangement remains within production specifications. Once the test cycle is completed, the assembly must return the DUT to its target location, such as a predetermined bin or collection point corresponding to the test results, and then properly eject the DUT from the assembly.

[0051] There are many ways to deliver the DUT to the device handler 500, but once the DUT is delivered, the DUT must be fixed in the correct position so that the position of the component leads corresponds to the appropriate test probe assignment. If the packaged device has a physical alignment element, such as a single taper angle that specifies pin 1, a component that is not properly aligned will not be properly installed at all. However, if the alignment structure is only a mark or feature that cannot prevent misalignment, a mechanism for alignment needs to be preset before the DUT is placed in the device handler. Once the device is aligned and placed in the handler, the vacuum chuck 510 firmly drags the component to the working position. The ejection pin 515 can be operated in a spring manner so that once the vacuum is released at the end of the test cycle, the component is lifted from the surface of the vacuum chuck to be placed in the subsequent processing element. A properly installed DUT will have its upper surface plane against the base bed 525 of this handler, and the connecting leads of the DUT will be held firmly against the surrounding lead support 530. When the handler engages the DUT with the test probes, the contact forces are counteracted by the lead supports 530 so that the leads themselves do not bend or twist during the engagement cycle.

[0052] An improperly positioned DUT risks damaging the test probe and, in turn, causing delays in testing due to the time required to repair or replace the test probe assembly. Misalignment is detected by the DUT not being mounted flat against the base bed 525, which would prevent the desired vacuum from being formed. Such an overpressure can be detected and a fault indication provided in response. The detection also detects the presence of any foreign matter that may prevent the DUT from being properly mounted and reduces the likelihood of an uncorrected fault. Figure 5 Inspection of the 507 shows that the handler consists of two major subassemblies: a bracket 505 that mates with the mechanical fittings of the test fixture, and a replaceable DUT-specific holder 507. Alignment marks 520 ensure that reassembly after service or replacement does not result in serious positioning errors due to any asymmetry of such components. In this particular illustration, the holder 507 is secured to the bracket 505 using screws to provide clamping force, but other methods can be used as long as the two subassemblies are securely secured. It has been found that by manufacturing the handler in two parts, versatility is increased and the setup for small DUT package replacement is greatly simplified.

[0053] Although the present invention has been described according to several embodiments, there are variations, modifications, permutations, and substitutions of equivalents that fall within the scope of the present invention. For example, many modifications are possible, and the above-mentioned features from various embodiments may be used alone or in combination. Although section headings are provided to help describe the present invention, these headings are illustrative only and are not intended to limit the scope of the present invention.

[0054] It should also be noted that there are many alternative ways to implement the methods and apparatus of the present invention. Therefore, it is intended that the appended claims be interpreted as including all such changes, modifications, permutations, and substitute equivalents that fall within the true spirit and scope of the present invention.

Claims

1. A test probe assembly for testing a packaged integrated circuit (IC) device under test (DUT), the test probe assembly comprising: a probe holder having a plurality of probe holding cavities, wherein the plurality of probe holding cavities are inclined relative to a longitudinal axis of the probe holder; a plurality of compressible angled probes configured to repeatedly maintain reliable electrical contact with a corresponding plurality of contacts of a packaged integrated circuit device under test while under a longitudinally compliant force along a longitudinal axis of the probe holder, each of the probes having a probe barrel, and oppositely extending upper and lower probe tips, wherein the probe barrel is contained within a corresponding one of the plurality of probe holding cavities, wherein at least one of the oppositely extending upper and lower probe tips of each of the probes is depressible into the probe barrel; wherein each of the upper probe tips comprises an upper section having a rectangular cross-section and a flat longitudinally-elongated chisel-shaped tip end, wherein each of the probe holding cavities comprises a corresponding rectangular cross-section hole to enable the flat longitudinally-elongated chisel-shaped tip end to protrude from a top surface of the probe holder, wherein the flat longitudinally-elongated chisel-shaped tip end is substantially parallel to an extended contact surface of one of the corresponding plurality of packaged integrated circuit device contacts under test, thereby enabling the flat longitudinally-elongated chisel-shaped tip end to provide a mechanical scraping action with the one of the corresponding plurality of packaged integrated circuit device contacts under test when subjected to the longitudinally-compliant force, and wherein each of the upper probe tips comprises a middle section adjacent to the upper section, and wherein a diagonal of a rectangular cross-section of the upper section is no greater than a diameter of a circular cross-section of the middle section.

2. The test probe assembly according to claim 1, wherein: The chisel-shaped tip is rounded at its distal end.

3. The test probe assembly according to claim 1, wherein: The chisel-shaped tip is chamfered at its distal end.

4. The test probe assembly according to claim 1, wherein: The chisel-shaped tip distal end has an area substantially parallel to a contact plane of a lead of the packaged integrated circuit device under test.

5. The test probe assembly according to claim 1, wherein: The lower probe tip is tapered, wherein the test probe assembly includes a lower block having a plurality of cylindrical channels for securing the lower probe tip.

6. The test probe assembly according to claim 1, wherein: A first subset of the plurality of probe holding cavities is counter-inclined relative to a second subset of the plurality of probe holding cavities.

7. The test probe assembly according to claim 1, wherein: The chisel-shaped tip ends of the first subset of the plurality of probes are configured to be arranged at 90 degrees relative to the chisel-shaped tip ends of the second subset of the plurality of probes.

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