CN112611900A - Package assembly attachment technique using UV-cured conductive adhesive - Google Patents

Abstract

Encapsulation assembly attachment techniques using UV-cured conductive adhesives are disclosed. A method for acquiring a signal from an encapsulated test point on a device under test, comprising: forming an aperture in the enclosure adjacent the test site, the aperture extending through the enclosure to the test site; delivering a UV curable conductive adhesive into the hole such that the delivered adhesive contacts the test point; applying UV light from a UV light source to cure the delivered adhesive; and connecting the conductive element between the cured adhesive and the test and measurement instrument.

Description

Package assembly attachment technique using UV-cured conductive adhesive

Cross reference to related applications.

This patent application is a partial continuation of co-pending U.S. patent application No.16/288,060 filed on 27.2.2019 and claiming benefit thereof, and co-pending U.S. patent application No.16/288,060 is a partial continuation of U.S. patent application No.15/978,090 filed on 11.5.2018 (which is now U.S. patent No.10,7390,381 published on 11.8.2020). This patent application also claims the benefit of U.S. provisional patent application No.62/910,347 filed on 3/10/2020. Each of these applications is incorporated by reference herein.

Technical Field

The present disclosure is directed to systems and methods for electrically and mechanically connecting electronic components together using an adhesive formulation cured by Ultraviolet (UV) light instead of solder, and more particularly to systems and methods for attaching test probes to test points of a device under test using a UV-cured conductive adhesive.

Background

Electrical devices, such as printed circuit boards, are typically evaluated by test and measurement equipment to provide information about the operation of the device. This may be done, for example, during development, production, or only when the device is not functioning properly after fabrication. By way of example, the test and measurement equipment may include a meter, a logic analyzer, and an observation appliance such as an oscilloscope. The connection between the Device Under Test (DUT) and the test and measurement equipment may be by way of probes.

There are many ways to connect test and measurement probes to contact points on a device under test. One of the most popular conventional methods is to solder the probe tips directly to the metal contacts on the DUT via generally short wires. This has been the standard for many years.

Soldering probe tips to DUTs can be challenging. For example, soldering requires a hot and often large soldering iron tip. The high temperatures typically required for lead-free solders to melt solder above 700 degrees fahrenheit (above 370 degrees celsius) also have a tendency to burn or burn the probe tip or portion of the DUT during the soldering process. This temperature problem is exacerbated because the solder tip is typically larger in size than the desired test point (such as a blind via) on the DUT, making it very difficult to apply high heat from the solder to only the desired test point. Although wires can be soldered between the probe tips and the DUT, the wires should be as short as possible for optimal electrical performance. But when using conventional soldering techniques, the shorter the wiring, the more difficult it is to perform the soldering attachment process. Still further, removal of solder in the probe tip or rework of the solder joint is difficult. And these problems are magnified by the ever shrinking geometries of DUTs, including printed circuit boards that are now significantly smaller than a penny.

Embodiments of the disclosed system and method address these and other problems in the art.

Drawings

Fig. 1 is a flow diagram illustrating an example method for curing a conductive adhesive using UV according to an embodiment.

Fig. 2 illustrates an example arrangement for using a UV-curable conductive adhesive according to an embodiment.

Fig. 3A and 3B illustrate an example of a process of applying pressure to cure a UV-curable conductive adhesive according to an embodiment.

Fig. 4 is a flowchart illustrating another example method for curing a conductive adhesive using UV according to an embodiment.

Fig. 5A, 5B, and 5C illustrate another example arrangement for using a UV-curable conductive adhesive according to an embodiment.

Fig. 6 illustrates examples of blind and buried vias.

Fig. 7 illustrates a process of accessing buried vias for signal detection purposes in accordance with an embodiment of the disclosed technology.

Fig. 8A and 8B illustrate a process for attaching a wire or probe tip to a device under test in accordance with an embodiment of the disclosed technology.

Fig. 9 illustrates conductive pins mated into backside drilled holes in a PCB in accordance with an embodiment of the disclosed technology.

Fig. 10 illustrates a non-conductive tip for dispensing a conductive UV-curable adhesive into a hole on a PCB in accordance with an embodiment of the disclosed technology.

Fig. 11 illustrates a process for attaching wires or probe tips to vias in a PCB using a UV-cured conductive adhesive in accordance with an embodiment of the disclosed technology.

Fig. 12 illustrates attaching a resistor with routing leads into vias in a PCB using a UV-cured conductive adhesive in accordance with an embodiment of the disclosed technology.

Fig. 13 is a flow diagram of another example method for curing a conductive adhesive using UV according to an embodiment.

Detailed Description

As described herein, embodiments of the present invention may assist a user (such as a test engineer) in temporarily attaching test probes directly to test points of a Device Under Test (DUT) using a conductive UV-cured conductive adhesive. As used in this disclosure, the term "UV-curable conductive adhesive" may include UV-curable epoxy resin. Existing connection techniques typically use soldering to temporarily attach probes, or pressure contacts (such as wiper probes) to retrieve signals from the DUT. In contrast to welding techniques, the described embodiments provide a faster and easier attachment system that eliminates the high heat and skill required by conventional welding techniques.

Fig. 1 is a flow chart illustrating a method for curing a conductive adhesive using UV in accordance with an embodiment of the disclosed technology. As illustrated in fig. 1, a method 100 for bonding a conductive element to a Device Under Test (DUT) may include: positioning 101 a conductive element proximate to an electrical connection point of a DUT; dispensing 102 a UV-curable conductive adhesive between the conductive element and the electrical connection point of the DUT; and bonding 103 the dispensed UV-curable conductive adhesive to the conductive elements and the electrical connection points of the DUT by applying UV light from the UV light source to the dispensed UV-curable conductive adhesive.

The conductive elements may be, for example, springs, pads, vias, traces, pins, connector contacts, wires, or other electrically conductive electrical contacts. Preferably, the conductive element is part of or coupled to the test probe tip.

As used in this disclosure, "positioning a conductive element proximate to an electrical connection point of a DUT" means: the conductive element is positioned so that the UV-cured conductive adhesive can create an electrical connection between the conductive element and an electrical connection point of the DUT. In other words, the conductive element may be touching the electrical connection point of the DUT. Alternatively, if not touched, the conductive elements can be sufficiently close to the electrical connection points of the DUT so that the UV-cured conductive adhesive can electrically and structurally bridge the distance between the conductive elements and the electrical connection points of the DUT. To determine whether the proximity is sufficiently close, the operator may perform an electrical continuity test between the conductive element and the electrical connection point of the DUT, for example, once the UV-curable conductive adhesive is cured.

The UV-curable conductive adhesive may be, for example, EMCAST 401 or EMCAST 501 conductive epoxy, each provided by Electronic Materials Incorporated of colorado brankenci. The UV curable conductive adhesive may also be a z-axis conductive UV curable material. The z-axis conductive UV curable material preferably has a compressive vertical conductive bonding composition that does not electrically bond in the cross-axis (x and y) directions while mechanically bonding in all directions. Such z-axis conductive material allows for close contact point alignment and selective vertical conduction, eliminating cross-connection to non-targeted electrical signals. Thus, for example, the UV curable conductive adhesive may be ELECOLIT 3065 anisotropic conductive adhesive available from Panacol-Elosol GmbH.

In embodiments, the conductive element or the electrical connection point on the DUT, or both, may be or include tin, lead solder, lead-free solder, gold, silver, or copper. Conventional adhesives or epoxies may not bond to those materials (in particular, gold, silver, and copper). Accordingly, in such embodiments, the UV-curable conductive adhesive is preferably an acrylic-based UV-curable conductive adhesive.

Preferably, the UV-curable conductive adhesive has a viscosity between about 15,000 centipoise and about 75,000 centipoise. The UV curable conductive adhesive preferably uses silver as the conductive filler in a proportion of approximately 75% filler material.

Preferably, the dispensed UV-curable conductive adhesive is continuously covering at least a portion of the conductive elements and at least a portion of the electrical connection points of the DUT. As noted, the UV-cured conductive adhesive will preferably electrically and structurally bridge the distance between the conductive elements and the electrical connection points of the DUT. Thus, in the present disclosure, "continuously" means spatially continuous in the sense of "continuously covering".

Accordingly, the amount of UV-curable conductive adhesive dispensed is at least that amount necessary to continuously cover at least a portion of the conductive element and at least a portion of the electrical connection points of the DUT. To determine if the amount is sufficient, the operator can perform an electrical continuity test between the conductive element and the electrical connection point of the DUT, for example, once the UV-curable conductive adhesive is cured.

In an embodiment, the dispensed UV-curable conductive adhesive may also be continuously covering at least a portion of the non-metallic region of the DUT. The non-metallic regions may be, for example, FR4, MEGTRON @, laminates of Teflon @, laminates of Polytetrafluoroethylene (PTFE) available from Rogers, Inc., as well as other substrate materials used with printed circuit boards. As noted above, the DUT may be or may include a printed circuit board. An example is the DUT substrate 214 shown in fig. 2 and fig. 5A-5C. Typically, the electrical connection points are embedded in or extend from the non-metallic region. In such embodiments, the dispensed UV-curable conductive adhesive bonds to the conductive elements, the electrical connection points of the DUT, and the non-metallic regions of the DUT by applying UV light from a UV light source to the dispensed UV-curable conductive adhesive. In contrast, conventional solders only adhere to a particular metallic surface. Bonding the dispensed UV-curable conductive adhesive to non-metallic areas of the DUT helps to reduce the risk of pulling electrical connection points of the DUT, such as pads, traces, and pins of a printed circuit board assembly.

As an example, the UV light source may be a hand-held battery-powered Light Emitting Diode (LED), such as a consumer-grade UV pencil torch or a laboratory-grade UV adjustable spotlight. In an example implementation, the UV light may have a wavelength between about 365 nanometers and about 460 nanometers, and the UV light from the UV light source may be applied to the dispensed UV-curable conductive adhesive for a duration between about twenty-five seconds and about thirty-five seconds. The operator can determine whether UV light has been applied for a sufficient period of time by, for example, visually inspecting the dispensed UV curable conductive adhesive. For example, an uncured UV-curable conductive adhesive may have a bright whitish appearance, while a cured UV-curable conductive adhesive may have a dull grayed appearance. As other examples, the operator may determine whether UV light has been applied for a sufficient period of time by reference to a timer or light intensity meter on or connected to the UV light source. The light intensity meter may determine the color-to-color shift of the phosphorescent material in, for example, a UV-cured conductive adhesive.

Fig. 2 illustrates an example arrangement for using a UV-curable conductive adhesive in accordance with an embodiment of the disclosed technology. As illustrated in fig. 2, the arrangement for attaching the test probes 201 to the DUT 202 using UV-curing conductive adhesive may include, for example: placing a droplet of UV-curable conductive adhesive 203 on a test point 204 of the DUT 202; placing the input wires, spring wires, or probe tips 205 of the test probes 201 into the adhesive 203; and applying UV light from UV light source 206 and optionally heat or optionally pressure from heat source 213 to cure UV-cured conductive adhesive 203, thereby bonding input wires, spring wires, or probe tips 205 to test points 204 and providing electrical connections between test probes 201 and DUTs 202. Test points 204 may be pads, vias, traces, pins, connector contacts, wires, or other electrically conductive electrical contacts on DUT 202. As noted above, the DUT 202 may be or may include a printed circuit board.

Returning to fig. 1, the operation of bonding the dispensed UV-curable conductive adhesive may further include: pressure is applied 104 to the electrical connection points of the conductive element and DUT to compress the dispensed UV curable conductive adhesive. Preferably, pressure is applied during the operation of applying 103 UV light from the UV light source to the dispensed UV curable conductive adhesive.

Fig. 3A and 3B illustrate an example process of applying pressure during an operation of curing a UV-curable conductive adhesive. Fig. 3B graphically shows an upper side of DUT 202 and a lower side of probe tip 205 (where "upper side" and "lower side" refer to fig. 3A), indicating representative locations of test points 204 on DUT 202 and corresponding points 207 on the lower side of probe tip 205. Each test point 204 of DUT 202 and each test point 207 of probe tips 205 may be a pad, via, trace, pin, connector contact, wire, or other electrically conductive electrical contact. As above, the test points 204 of the DUT 202 may be embedded in non-metallic regions of the DUT 202 or may extend from non-metallic regions of the DUT 202. Similarly, test point 207 of probe tip 205 may be embedded in a non-metallic region of probe tip 205 or may extend from a non-metallic region of probe tip 205.

As illustrated in fig. 3A, in order to apply pressure to cure the UV-curing conductive adhesive while providing the UV light, the applicator 209 may include a UV light source 206 and a tapered tip 210. The UV light source 206 may shine UV light through the tapered tip 210, and the tapered tip 210 may contact the probe tip 205 while the UV-curable conductive adhesive is being compressed between the probe tip 205 and the DUT 202. The tapered tip 210 is formed from a material that will transmit UV light. The tapered tips 210 may be made of, for example, fluorinated ethylene propylene (such as The Chemours Company FC, LLC of TEFLON FEP or The Chemours Company FC, LLC of PTFE). Probe tips 205 can be made of clear or translucent material to allow UV light from UV light source 206 to pass through probe tips 205 and illuminate test points 204 of DUT 202 and test points 207 of probe tips 205. Accordingly, while test points 204 of DUT 202 and test points 207 of probe tips 205 are in the cured adhesive, applicator 209 may apply UV light to cure the UV cured conductive adhesive while also providing pressure to probe tips 205 through physical contact of tapered tips 210. Fig. 3A shows a UV-curable conductive adhesive being applied to test points 204 of DUT 202 and test points 207 of probe tips 205 by syringe 208, although the UV-curable conductive adhesive may be applied in any suitable manner.

The implementation shown in fig. 3A and 3B is particularly useful for embodiments where the UV-cured conductive adhesive is a z-axis conductive UV material. For example, a test point on the DUT and a corresponding point on the underside of a probe tip may be alongside or near other undesirable points. However, the z-axis conductive UV material only allows conduction to occur in one axis, the axis between the test point on the DUT and the corresponding point on the probe tip, thus reducing or preventing shorting to adjacent undesired points.

Returning to fig. 1, the operation of joining the dispensed UV-curable conductive adhesive may further include: heat is applied 105 from a heat source to the dispensed UV curable conductive adhesive. Preferably, the heat is applied after the operation of applying 103 UV light from the UV light source to the dispensed UV curable conductive adhesive. The heat source 213 (see fig. 2) may be, for example, a conventional skills heat gun or a hobby (hobby) heat gun. In an example implementation, the heat may have a temperature of less than about 200 degrees celsius (about 390 degrees fahrenheit) and the heat may be applied to the dispensed UV-curable conductive adhesive for a duration of between about twenty-five seconds and about thirty-five seconds. Preferably, heat is applied to raise the temperature of the dispensed UV-curable conductive adhesive to about 100 degrees celsius (about 210 degrees fahrenheit) in about thirty seconds. Temperatures greater than about 200 degrees celsius (about 390 degrees fahrenheit) may thermally degrade DUTs with conventional substrates, such as FR4 substrates, if heat is applied for a period of time substantially longer than typical cure times of about sixty seconds or less.

Thus, the dispensed UV-curable conductive adhesive can preferably be bonded to the conductive elements and electrical connection points of the DUT by: (a) applying UV light from a UV light source to the dispensed UV curable conductive adhesive without applying heat or pressure; (b) applying UV light from a UV light source to the dispensed UV curable conductive adhesive and then applying heat from a heat source to the dispensed UV curable conductive adhesive without applying pressure; or (c) applying UV light from a UV light source to the dispensed UV curable conductive adhesive and simultaneously applying pressure to the dispensed UV curable conductive adhesive without applying heat.

Fig. 4 is a flow chart illustrating a method for curing a conductive adhesive using UV in accordance with an embodiment of the disclosed technology. As illustrated in fig. 4, a method 400 for engaging conductive elements between electrical connection points of a test probe tip and electrical connection points of a Device Under Test (DUT) may include: positioning 401 a first portion of a conductive element proximate to an electrical connection point of the DUT; dispensing 402 a first quantity of UV-curable conductive adhesive between a first portion of a conductive element and an electrical connection point of the DUT; bonding 403 a first quantity of dispensed UV-curable conductive adhesive to the first portion of the conductive element and the electrical connection point of the DUT by applying UV light from the UV light source to the first quantity of dispensed UV-curable conductive adhesive; positioning 406 a second portion of the conductive element proximate to an electrical connection point of the test probe tip; dispensing 407 a second quantity of UV curable conductive adhesive between the second portion of the conductive element and the electrical connection point of the test probe tip; the second quantity of dispensed UV curable conductive adhesive is bonded to the second portion of the conductive element and the electrical connection points of the test probe tips by applying 408 UV light from the UV light source to the second quantity of dispensed UV curable conductive adhesive.

The first amount of UV curable conductive adhesive and the second amount of UV curable conductive adhesive may be the same amount of UV curable conductive adhesive, or they may be different amounts.

The operation of bonding the first quantity of dispensed UV-curable conductive adhesive to the first portion of the conductive element may further comprise: pressure is applied 404 to the first portion of the conductive element and the electrical connection points of the DUT to compress the first quantity of dispensed UV curable conductive adhesive during the operation of applying 403 UV light from the UV light source. Similarly, the operation of bonding the second quantity of dispensed UV-curable conductive adhesive to the second portion of the conductive element may further comprise: pressure is applied 409 to the second portion of the conductive element and the electrical connection point of the DUT to compress the second quantity of dispensed UV curable conductive adhesive during the operation of applying 408 UV light from the UV light source.

The operation of bonding the first quantity of dispensed UV-curable conductive adhesive to the first portion of the conductive element may further comprise: heat is applied 405 from a heat source to the first quantity of dispensed UV curable conductive adhesive. Similarly, the operation of bonding the second quantity of dispensed UV-curable conductive adhesive to the second portion of the conductive element may further comprise: heat is applied 410 from the heat source to the second quantity of dispensed UV curable conductive adhesive.

The processes and materials in the method 400 of fig. 4 are as described above for similar processes and materials in the method 100 of fig. 1, including the settings and options shown and described with respect to fig. 2 and 4. Note that the first portion of the conductive element may be, for example, a first end of the conductive wiring. It is further noted that the second portion of the conductive element may be, for example, a second end of the conductive wiring opposite the first end of the conductive wiring.

As used in this disclosure, "positioning a first portion of a conductive element proximate to an electrical connection point of a DUT" means: the first portion of the conductive element is positioned so that the UV-curable conductive adhesive can create an electrical connection between the first portion of the conductive element and an electrical connection point of the DUT. In other words, the first portion of the conductive element may be touching the electrical connection point of the DUT. Alternatively, if not touched, the first portion of the conductive element can be sufficiently close to the electrical connection point of the DUT that the UV-cured conductive adhesive can electrically and structurally bridge the distance between the first portion of the conductive element and the electrical connection point of the DUT. To determine whether the proximity is sufficiently close, the operator may perform an electrical continuity test between the first portion of the conductive element and the electrical connection point of the DUT, for example, once the UV-curable conductive adhesive is cured.

Similarly, as used in this disclosure, "positioning the second portion of the conductive element proximate to the electrical connection point of the test probe tip" means: the second portion of the conductive element is positioned so that the UV-curable conductive adhesive can create an electrical connection between the second portion of the conductive element and the electrical connection point of the test probe tip. In other words, the second portion of the conductive element may be touching the electrical connection point of the test probe tip. Alternatively, if not touched, the second portion of the conductive element may be sufficiently close to the electrical connection point of the test probe tip so that the UV-curable conductive adhesive may electrically and structurally bridge the distance between the second portion of the conductive element and the electrical connection point of the test probe tip. To determine whether the proximity is sufficiently close, the operator may perform an electrical continuity test between the second portion of the conductive element and the electrical connection point of the test probe tip, for example, once the UV-curable conductive adhesive is cured.

Preferably, the first quantity of dispensed UV-curable conductive adhesive is continuously covering at least a portion of the first portion of the conductive element and at least a portion of the electrical connection points of the DUT. Preferably, the second quantity of dispensed UV-curable conductive adhesive is continuously covering at least a portion of the second portion of the conductive element and at least a portion of the electrical connection points of the test probe tips. As with fig. 1 above, therefore, "continuously" in the sense of "continuously covering" in this disclosure means spatially continuous.

Thus, for the method 400 of fig. 4, the dispensed UV-curable conductive adhesive preferably can be suitably bonded to electrical connection points to conductive elements and DUT or test probe tips by: (a) applying UV light from a UV light source to the dispensed UV curable conductive adhesive without applying heat or pressure; (b) applying UV light from a UV light source to the dispensed UV curable conductive adhesive and then applying heat from a heat source to the dispensed UV curable conductive adhesive without applying pressure; or (c) applying UV light from a UV light source to the dispensed UV curable conductive adhesive and simultaneously applying pressure to the dispensed UV curable conductive adhesive without applying heat.

Fig. 5A-5C illustrate an example arrangement for using a UV-curable conductive adhesive in accordance with an embodiment of the disclosed technology. As illustrated in fig. 5A-5C, arrangements for attaching the test probes 201 to the DUT 202 using UV-cured conductive adhesive may include, for example: placing a drop of UV-curable conductive adhesive 203 on a test point 204 of the DUT 202; placing the distal ends 211 of the input wires or the probe tips 205 of the test probes 201 into the adhesive 203; and applying light, and perhaps pressure or heat, from light source 206 to cure the UV-curable conductive adhesive 203, thus bonding the distal ends 211 of the input wires or probe tips 205 to the test points 204 and providing electrical contact between the test probes 201 and the DUT 202.

In a corresponding manner, proximal end 212 of the input wiring or probe tip 205 may be joined to test probe 201 through test point 207 of test probe 201.

Each test point 204 of DUT 202 and each test point 207 of probe tips 205 may be a pad, via, trace, pin, connector contact, wire, or other conductive contact point. As above, the test points 204 of the DUT 202 may be embedded in non-metallic regions of the DUT 202 or may extend from non-metallic regions of the DUT 202. Likewise, test point 207 of probe tip 205 may be embedded in a non-metallic region of probe tip 205 or may extend from a non-metallic region of probe tip 205.

Although fig. 5 is shown as the UV curable conductive adhesive being applied by syringe 208, the UV curable conductive adhesive may be applied in any suitable manner.

In embodiments where the dispensed UV-cured conductive adhesive is bonded to a non-metallic region of the DUT, the UV-cured conductive adhesive is preferably an acrylic-based UV-cured conductive adhesive. Additionally, in embodiments in which pressure is not applied to compress the dispensed UV-curable conductive adhesive (e.g., embodiments lacking operation 104 of fig. 1 and embodiments lacking operations 404 and 409 of fig. 4), the UV-curable conductive adhesive is preferably an acrylic-based UV-curable conductive adhesive. Additionally, in embodiments where neither pressure nor heat is applied to the dispensed UV-curable conductive adhesive (e.g., embodiments lacking operations 104 and 105 of fig. 1 and embodiments lacking operations 404, 405, 409, and 410 of fig. 4), the UV-curable conductive adhesive is preferably an acrylic-based UV-curable conductive adhesive. Preferably, the acrylic-based UV-curable electrically conductive adhesive is a free radical UV-reactive acrylate, which incorporates electrically conductive particles that also have auxiliary thermal conductivity capabilities.

Thus, when the DUT is relatively small, conventional soldering is not an effective way to join a test probe or other electronic component to a test point of the DUT. That is, because of the heat involved, conventional soldering techniques tend to destroy the electronic component that is too close to the soldering iron, necessitating a distance between the point of solder contact and the electronic component. However, this distance, as well as the variable geometry of the solder drop itself, adds unpredictable parasitics that are difficult to correct using standard calibration and Digital Signal Processing (DSP) techniques.

Embodiments described in this disclosure provide some or all of the following advantages: (a) no 700 degree fahrenheit iron is required; (b) UV-curable conductive adhesives are relatively fast to use when compared to conventional soldering techniques; (c) UV cured conductive adhesive to FR4 and other circuit board substrate materials; (d) easy cleaning: prior to curing, the UV-curable conductive adhesive may be wiped off with isopropyl alcohol and a wipe; (e) the user can position the probe tip near the DUT test point contact instead of positioning the probe tip over the DUT test point contact and bridge to the contact with adhesive; (f) easy removal/rework: after curing, the adhesive can be removed by heat or by a common solvent, leaving the DUT; and (g) repeatability of connections: the UV-curable adhesive can be successfully applied repeatedly to the same test point.

For optimized electrical performance of a test probe (such as test probe 201 in fig. 5A-5C), especially when test probe 201 is being used to measure high frequency signals, it is desirable to minimize the electrical length between test point 204 on the DUT and test point 207 on test probe 201; that is, the length of the wiring or probe tips 205 is minimized. As mentioned, the heat and skill required by conventional solder attachment techniques tends to force the length of the wiring 205 to be relatively long in practice, thereby adversely affecting the performance of the test probe 201. In contrast, embodiments of the disclosed technique allow the length of the wiring 205 to be relatively short, thereby improving the performance of the test probe. Furthermore, in some embodiments, the wiring or probe tips 205 are integrated into or fabricated as part of the test probes 201 (such as in the test probes 201 shown in fig. 2). In these embodiments, the wiring or probe tips 205 may be fabricated to a consistent and known length, allowing calibration of the test probe 201 to be performed all the way through to the distal ends 211 of the probe tips 205 at the time of fabrication. With this degree of calibration, DSP techniques can be used to correct and remove electrical loading effects of the test probes 201 on the DUT and provide the user with a more accurate measurement of the signal being measured.

Still further, the electrical performance of the test probe 201 is also improved when the test probe 201 includes resistive or impedance elements as close as possible to the electrical connection points 104, 204 on the DUT. For example, the test probe 201 illustrated in fig. 2 includes a small conventional resistor at the distal end of the probe tip 205. However, in some embodiments of the disclosed technology, the UV-cured conductive adhesive is a resistive formulation. That is, in some embodiments, the UV-cured conductive adhesive is only partially conductive and exhibits a resistance or impedance when measured across the dispensed amount of adhesive. Such resistive formulations may contain, for example, a mixture of silver and carbon as the conductive filler element, with the relative proportions of these materials controlling the amount of resistance per unit volume of adhesive. Thus, in these embodiments, since the UV-cured conductive adhesive is in direct contact with the electrical connection points 104, 204 on the DUT, conventional resistors at the distal ends of the probe tips 205 can be eliminated, and the dispensed UV-cured conductive adhesive itself acts as a resistive element of the test probe 201, thereby further improving the electrical performance of the test probe 201.

Backside drilled via application.

A Printed Circuit Board (PCB) via is a structure used to connect a trace on one layer to a trace on one or more other layers. It is common practice today to use vias as test points on a PCB. When a via extends through all layers of the PCB, the via will typically connect to a pad on a surface layer of the PCB. In these cases, a user of a test and measurement instrument, such as an oscilloscope, may easily touch or otherwise electrically connect contact pins of a measurement accessory, such as a probe, to the surface layer pads to acquire and measure signals of interest delivered by vias of interest in the PCB.

However, for some vias in some PCBs, there are no surface layer pads to which probes can be connected. For example, vias may be classified as blind or buried vias when the vias do not extend through all layers of the PCB. Fig. 6 illustrates an example of a cross section of a blind hole 610 and a buried hole 620. As with normal vias, blind vias such as the example blind via 610 are typically copper plated holes through layers of a Printed Circuit Board (PCB) 600a, except that the blind vias interconnect only one external layer of the PCB 600a (such as the example layer 602) with one or more internal layers of the PCB 600a (such as the example layer 604) rather than travel all the way through all the layers of the PCB 600 a. A buried via, such as exemplary buried via 620, is a copper plated via in PCB 600b that interconnects one or more layers of PCB 600b, such as exemplary layers 606 and 608, but is not connected to an external layer, such as exemplary layer 612, and thus via 620 is completely inside PCB 600b or buried within PCB 600 b. The buried via is typically not visible when viewing the exterior surface of the PCB.

Fig. 7 illustrates a process of backside drilling of PCB 700 for signal detection purposes in order to access blind or buried vias, such as the example blind via 710. Some blind holes, as well as all buried holes, are difficult to detect. Blind holes are sometimes difficult to detect due to their depth in the circuit board. While the blind via has a surface layer pad (such as surface layer pad 712 of example blind via 710), a component such as BGA 730 will often be mounted to the pad, thereby blocking physical access to the pad for probing. In these cases, blind hole 710 may be backside drilled using drill 740 to form hole 750 to access via 710. Buried vias are not normally used for probing in the final product, but during product development, due to the need to troubleshoot unforeseen problems in the signal, the buried vias will be back-drilled to reach the buried vias for probing purposes. In all cases, the ability to stop the drilling tool 740 precisely at the end 714 of the via 710 without damaging the next layer of the PCB 700 is uncommon.

Embodiments of the presently disclosed technology generally include a delivery method for applying a UV-cured conductive adhesive to allow probing of buried vias that are either blind-drilled or backside-drilled. One objective of the presently disclosed technology is to minimize possible wicking of the adhesive in its wet form prior to curing. Another object of the presently disclosed technology is to minimize cross-talk signals and transient signals reaching the detection device.

Aspects of the disclosed technology include processes for delivering UV-cured conductive adhesive into holes, such as backside-drilled vias 750 in PCB 700. Fig. 8A and 8B illustrate an example 800 of such a process, including: at operation 810, an amount of UV-curable conductive adhesive 812 is dispensed into aperture 750; at operation 820, a conductive member 822 (e.g., a wire, pin, etc.) is inserted into the aperture 750; at operation 830, curing the adhesive 812 using the UV light source 832 and optionally a heat source (not shown) to secure the conductive member 822 in the hole 750 for probing at the surface of the PCB 700; or alternatively at operation 840, solder-in probes (SIA) 842 are attached to conductive members 822. In some embodiments, the conductive member 822 includes a portion of a probe tip for the welding probe 842.

Fig. 9 illustrates another aspect of the disclosed technology, including conductive pins 910 that fit into holes 902 in PCB 901. The pins may be stepped, with a larger tip 912 than the tip 911. A tip 911 is inserted into the hole 902 and conductively coupled to the via/trace 903 of interest by a UV-cured conductive adhesive 920 dispensed into the bottom of the hole 902. The large top 912 provides a contact area that a user can use to probe signals using a browser-type probe 930, such as a P7700 series probe browser tip manufactured by Tektronix corporation. The large top may also extend beyond the PCB 901 surface. The large top 912 may have a diameter larger than the hole 902 in the PCB 901. In some embodiments, the large top 912 may include integrated standard connectors (such as square pins, etc.) to allow direct electrical connection between the pins 910 and a test and measurement instrument (not shown). In some embodiments, the pin 910 may include a separation feature 913 that allows the top 912 to be removed (and also the extra electrical length created by the pin top 912) when the user is finished probing the PCB test point. After detaching the top 912, the hole 902 may be filled with a conventional non-conductive epoxy to close the hole 902.

Other aspects of the disclosed technology include solutions for when a hole being backside drilled accidentally invades into unintended traces or transmission lines. For example, if the diameter of the hole being backside drilled is made too large, the hole may inadvertently contact other traces around the location of the via of interest. In these cases, if the hole is filled with a conductive adhesive, the conductive adhesive will undesirably connect these other traces together with the trace/via of interest to be probed.

As a solution to these situations, fig. 10 illustrates another embodiment of the disclosed technique, which uses a non-conductive thin-walled translucent tube 1010, the non-conductive thin-walled translucent tube 1010 being a close clearance fit into a hole 1002 in a PCB 1001. A tight clearance fit means that the outer diameter of the tube 1010 is substantially the same as the diameter of the hole 1002 being back-drilled. Such a close clearance fit will keep the tube 1010 straight, close to each side of the hole 1002. Tube 1010 provides the following flow paths: which is used to travel the dispensed conductive adhesive 1020 toward the trace/via 1003 of interest without the adhesive 1020 touching any other layer/trace 1004 in the hole 1002 being drilled. Since the tube 1010 is non-conductive, it forms an electrically insulating barrier between the conductive adhesive 1020 and the walls of the hole 1002 (which may touch other traces 1004). Openings 1012 in the tube 1010 provide a direct path to insert wires, pins, or other conductive members 1022 (see fig. 11) down into the dispensed conductive adhesive 1020 to pass signals at the traces/vias 1003 of interest outside of the holes 1002 and to, for example, attached probe tips. Since the wall of the tube 1010 is translucent, it acts as a light pipe that transmits UV light from the UV light source 1032 (see fig. 11) to the dispensed conductive adhesive 1020 even when the conductive member 1022 is inserted into the tube 1010. Therefore, the dispensed UV-curing conductive adhesive 1020 may be efficiently cured even when the conductive member 1022 is inserted into the tube. In a preferred exemplary embodiment, the tube 1010 may be formed of Polytetrafluoroethylene (PTFE) (also known commercially as TEFLON) or nylon, both of which provide good electrical insulation and are desirably translucent. In some embodiments, the conductive member 1022 includes portions of a probe tip.

Once tube 1010 is held in place in the hole, the user can insert a small needle-like UV curable conductive adhesive container/dispenser 1030 (e.g., a syringe) through tube 1010 to dispense the appropriate amount of adhesive 1020 as needed. After the uncured adhesive 1020 is dispensed in place, the user may insert conductive members 1022 (wires, pins, etc.) into the tube 1010 and then cure the adhesive 1020. This will make it much easier for the user to have improved adhesive flow control before curing and, particularly in the case of backside drilled vias, reduce wicking of the adhesive to the exposed layer (which may cause electrical problems). When the adhesive 1020 has been cured to secure the conductive member 1022 in the hole 1002, probe tips or probes may be attached to the conductive member to probe signals or points of interest in the via of interest.

Some manufacturers of UV-curable adhesive containers/dispensers use nylon tubing at the end of the dispenser. With the appropriate choice of dispenser tip size, in some embodiments, the dispenser tip itself may form the tube 1010. The use of nylon tips may provide the following advantages: the nylon is flexible enough to be utilized even for cutting at the surface of the PCB 1001 and can be left in place after curing without adverse electrical impact on the measured signal. Fig. 11 illustrates such an embodiment.

Fig. 12 illustrates an exemplary embodiment in which the conductive member inserted into the hole is a resistor 1212 having routing leads. This method can be used in conjunction with the SIP tip when customers require a specific resistance in their measurements. In some embodiments, resistor 1212 includes a portion of a probe tip.

Other aspects of the disclosed technology include a project toolkit that will provide the user with a complete solution for attaching wires or probe tips to test points on a device under test (such as vias on a PCB) using a UV cured conductive adhesive. These kits include a packaged quantity of UV-curable conductive adhesive, UV light sources, and dispensing tips and/or pins according to the disclosed techniques.

Some PCB designs require backside drilled vias to improve the high speed electrical performance of the PCB. The most common and least expensive method of creating vias involves drilling holes through all layers of the PCB and plating the inside of the holes with metal so that any trace on any layer touching a hole will be electrically connected. However, the presence of metal plating in the holes beyond the layers at which the traces touch the vias appears as a stub of a transmission line that interferes with high-speed signal propagation along the traces connected by the vias. To alleviate these stubs, some PCB fabrication processes allow vias to be "backside drilled". In the backside drilling process, a drill having a slightly larger diameter than the via is inserted to a partial depth and used to remove the plated unwanted portion forming the stub. The holes that are backside drilled are then typically filled with a non-conductive epoxy to form a mechanical seal.

While backside drilling provides a much cleaner transmission line environment for signals routed through vias, it eliminates the use of vias as possible probe points for evaluation and/or debugging of the completed PCB. In practice, critical high speed signal lines may be routed from one Ball Grid Array (BGA) package below to another BGA package below through backside drilled vias and internal layer traces, leaving no probe access to the signals at all.

Even if it is desired to place probe tips down into the backside drilled portion of the via to access the signal without the non-conductive epoxy, the inserted probe tips will become transmission line stubs as they are already in the non-drilled via, disturbing the probed signal and creating similar undesirable signal effects as stubs.

One solution to this dilemma is to fill the backside drilled vias with a resistively formulated UV cured adhesive instead of a non-conductive epoxy as discussed above. The UV-cured resistive adhesive may be similar in nature to the resistive solder paste used to form the resistor on a hybrid circuit or in an internal layer of a PCB. Most high speed probes contain series resistors faithfully near the probe tip for the purpose of unambiguously minimizing the stub effect of the tip. Embodiments of the disclosed technology include the use of UV-cured resistive adhesive to effectively place a series tip resistor (e.g., resistor 1212, when integrated into a probe tip) directly in a via that is backside drilled rather than in a probe. Thus, the UV-cured resistive adhesive acts as both the electromechanical connection between the via and probe of interest and the probe tip resistor itself. The user can then place the probe tip over the resistive epoxy at the end of the via that is back drilled with less effect on the signal to be tested than would be seen if the conductive stub extended out to the resistor in the probe itself.

The value of the via resistor will have a direct effect on the high frequency gain of the probe and thus the resistance value will need to be known or determined in order to properly measure the signal to be tested. The resistance value may vary from one via to another or from one PCB to another due to the diameter and depth of the backside bore and possibly the adhesive resistivity. Thus, it means that a probe operating in such an environment should have some form of de-embedded capability in which it is able to measure the source impedance (now a combination of DUT signal impedances in series with the resistive epoxy plug) and compensate for the effect of the source impedance driving the probe load.

A practical limitation of this approach is direct connection and/or capacitive coupling from traces on other layers that touch or are near the portion of the via that is backside drilled to the via probe resistor and into the probe. Trace clearance and/or ground shield structures around any backside drilled vias intended for probing would be helpful in minimizing these considerations.

Encapsulated assembly applications.

Test and measurement probes, such as the IsoVu series of insulation probes available from the Tektron Nick company, may be used to probe pins of components on a Printed Circuit Board (PCB) and transmit signals of interest from the probed components to a test and measurement instrument, such as an oscilloscope, for viewing and analysis. In particular, for example, an IsoVu probe may be used to measure current flowing through a power device, such as a Metal Oxide Silicon Field Effect Transistor (MOSFET) device, a silicon carbide (SiC) device, or a gallium nitride (GaN) device. Such devices may be mounted on a PCB and typically have three pins, also known as leads or pins, which may be probed.

During the design phase and the debug phase of evaluating the circuit and PCB design, components such as these MOSFET devices are typically left open to air so that conventional probing techniques can be used. However, once the debug phase is complete and the design is sufficient and the production phase is entered, manufacturers typically use an encapsulation process to encapsulate the devices. Encapsulation generally involves pouring a non-conductive liquid epoxy or resin around the device. The encapsulant then hardens to seal the assembly from air, moisture, and other environmental factors. This process makes probing impossible once the encapsulation has been completed.

However, in another aspect of the disclosed technology, the process may be used to electrically connect to the device to be measured through the solidified encapsulant. Generally, according to embodiments of the disclosed technology, by forming a hole through the encapsulant material, electrical contact can be established with the device through the use of a UV curable conductive adhesive. With electrical contact established, a signal can be taken from the encapsulated test site.

Fig. 13 illustrates an exemplary embodiment of a method 1300 for acquiring a signal from an encapsulated test point on a device under test.

At 1301, a hole is formed in the encapsulant material around the test site. The holes may be formed using any suitable technique, including physical drilling, laser drilling, chemical treatment, and the like. Holes should be formed through the encapsulant at appropriate locations and depths to contact pins, leads, pins, solder balls, pads, vias or other test points of the device that are required for probing. In some embodiments, the holes are formed at an angle substantially normal to the surface of the test point to provide good conductivity to the test point.

At 1302, an amount of UV curable conductive adhesive is delivered into the formed hole. The UV curable conductive adhesive should be delivered into the hole so that it makes contact with the test point. In some embodiments, the adhesive is delivered into the hole by inserting a tube containing a volume of adhesive into the hole such that the adhesive contacts the test point. In some embodiments, since the adhesive is a liquid prior to curing and the tube is generally open at both ends, the adhesive should have sufficient viscosity to remain in the tube during insertion into the hole while still flowing sufficiently to spread onto the test site once the tube has been minimized in the hole to create good physical coverage of the test site. In some embodiments, the end of the tube may be filled with a volume of adhesive by first loading the adhesive into the tube using an injection type device. In other embodiments, the tube may be a removable part of a dispenser apparatus for the adhesive. That is, the UV curable adhesive dispenser may have a single use or removable tip. The user may dispense a preset amount into the tip and then remove the tip, which then functions as a tube. In still other embodiments, a tube pre-filled with a predetermined volume of adhesive may be supplied to a user. Such tubes may be provided with end closures so that the adhesive does not leak during shipment to the user. The user may remove one or both end closures from the tube just before they are ready for use. Such tubes may be supplied in a kit, which may contain a plurality of tubes. The multiple tubes may have different diameters for use with different sized holes. The plurality of tubes may also contain different formulations of UV curable adhesive, such as formulations having different bulk resistivities, as discussed above.

At 1303, UV light is applied from a UV light source to cure the adhesive delivered into the holes. In some embodiments, the UV light is applied by using a tube with a translucent wall such that the translucent wall forms a UV light pipe for the UV light to reach and cure the UV curable adhesive at the test point in the hole. In a preferred embodiment, the tube used to deliver the UV curable adhesive into the hole is the same tube through which the UV light is applied.

At 1304, the conductive element is connected between the cured adhesive and a test and measurement instrument (such as, for example, an oscilloscope). In some embodiments, the conductive element is placed into the delivered adhesive in the hole prior to applying UV light to the adhesive, such that the conductive element is physically secured in place when the adhesive cures. In some embodiments, the conductive element may be a wire, a resistive element, or a portion of a probe or probe tip. In some embodiments, the UV curable conductive adhesive may have a resistive formulation such that the adhesive itself forms the series tip resistor of the probe, as discussed above. In some embodiments, the conductive elements may be pins as follows: which has a top that can protrude outside the hole and form a probing surface, similar to the pins discussed above. The probe may then be coupled between the probing surface and the test instrument. In some embodiments, the conductive element may comprise a connector. A cable may then be connected between the connector and the test instrument.

At 1305, an electrical signal at a test point may be acquired using the connected test and measurement instrument. For example, a test instrument may be used to measure the current flowing through a test point.

Aspects of the disclosure may operate on specially constructed hardware, firmware, digital signal processors, or a specially programmed general-purpose computer (which includes a processor operating according to programmed instructions). The term controller or processor as used herein is intended to include microprocessors, microcomputers, Application Specific Integrated Circuits (ASICs), and application specific hardware controllers. One or more aspects of the present disclosure may be embodied in computer-usable data and computer-executable instructions, such as in the execution of one or more program modules by one or more computers (including a monitoring module) or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a non-transitory computer readable medium such as a hard disk, an optical disk, a removable storage medium, a solid state memory, a Random Access Memory (RAM), and the like. As will be appreciated by one skilled in the art, the functionality of the program modules may be combined or distributed as desired in various aspects. Further, the functionality may be embodied in whole or in part in firmware or hardware equivalents such as integrated circuits, FPGAs, etc. Particular data structures may be used to more effectively implement one or more aspects of the present disclosure, and such data structures are contemplated within the scope of the computer-executable instructions and computer-usable data described herein.

The disclosed aspects may, in some cases, be implemented in hardware, firmware, software, or any combination thereof. The disclosed aspects may also be implemented as instructions carried by or stored on one or more non-transitory computer-readable media, which may be read and executed by one or more processors. Such instructions may be referred to as a computer program product. Computer-readable media as discussed herein means any media that can be accessed by a computer device. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media.

Computer storage media means any media that can be used to store computer-readable information. By way of example, and not limitation, computer storage media may include RAM, ROM, electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), Digital Video Disc (DVD), or other optical disc storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, and any other volatile or non-volatile, removable or non-removable media implemented in any technology. Computer storage media excludes signals per se and transient forms of signal transmission.

Communication media means any media that can be used for the communication of computer readable information. By way of example, and not limitation, communication media may include coaxial cables, fiber optic cables, air, or any other medium suitable for communication of electrical, optical, Radio Frequency (RF), infrared, acoustic, or other types of signals.

Additionally, this written description refers to particular features. It is to be understood that the disclosure in this specification includes all possible combinations of these specific features. For example, where a particular feature is disclosed in the context of a particular aspect, that feature can also be used, to the extent possible, in the context of other aspects.

In addition, when reference is made in this application to a method having two or more defined steps or operations, the defined steps or operations may be performed in any order or may be performed simultaneously, unless the context excludes these possibilities.

While specific aspects of the present disclosure have been illustrated and described for purposes of illustration, it will be understood that various modifications may be made without deviating from the spirit and scope of the disclosure. Accordingly, the disclosure should not be limited except as by the appended claims.

Examples of the invention

Illustrative examples of the disclosed technology are provided below. Embodiments of the technology may include one or more of the examples described below, as well as any combination.

Example 1 includes a method of conductively bonding a test probe tip having a conductive element to a Device Under Test (DUT) having an electrical connection point, the method comprising: positioning the conductive element of the test probe tip proximate to the electrical connection point of the DUT; dispensing a UV-curable conductive adhesive between said conductive element and said electrical connection point of said DUT, said dispensed UV-curable conductive adhesive continuously covering at least a portion of said conductive element and at least a portion of said electrical connection point of said DUT; and bonding the dispensed UV-curable conductive adhesive to the conductive elements and the electrical connection points of the DUT by applying UV light from a UV light source to the dispensed UV-curable conductive adhesive.

Example 2 includes the method of example 1, wherein applying UV light from a UV light source to the dispensed UV-curable conductive adhesive includes: applying UV light from a UV light source to the dispensed UV-curable conductive adhesive for a duration of between about twenty-five seconds and about thirty-five seconds, the UV light having a wavelength between about 365 nanometers and about 460 nanometers.

Example 3 includes the method of any of examples 1-2, the operation of joining the dispensed UV-curable conductive adhesive further comprising: heat is applied from a heat source to the dispensed UV-curable conductive adhesive.

Example 4 includes the method of example 3, wherein applying heat from the heat source to the dispensed UV-curable conductive adhesive comprises: applying heat from a heat source to the dispensed UV-curable conductive adhesive for a duration of between about twenty-five seconds and about thirty-five seconds, the heat having a temperature of less than about 200 degrees Celsius.

Example 5 includes the method of any one of examples 1-4, further comprising: applying pressure to the conductive elements and the electrical connection points of the DUT to compress the dispensed UV-curable conductive adhesive during operation of applying UV light from the UV light source.

Example 6 includes the method of any of examples 1-5, wherein dispensing a UV-curable conductive adhesive between the conductive element and the electrical connection point of the DUT is: distributing a z-axis conductive UV-curable adhesive between the conductive element and the electrical connection point of the DUT.

Example 7 includes the method of any of examples 1-6, wherein dispensing a UV-curable conductive adhesive between the conductive element and the electrical connection point of the DUT is: dispensing a UV-curable conductive adhesive between the conductive element and the electrical connection point of the DUT, the UV-curable conductive adhesive having a viscosity between about 50,000 centipoise and about 75,000 centipoise.

Example 8 includes the method of any of examples 1-7, wherein the dispensed UV-curable conductive adhesive is also continuously covering at least a portion of a non-metallic region of the DUT, and wherein joining the dispensed UV-curable conductive adhesive to the conductive element and the electrical connection point of the DUT by applying UV light from a UV light source to the dispensed UV-curable conductive adhesive is: bonding the dispensed UV-curable conductive adhesive to the conductive elements, the electrical connection points of the DUT, and the non-metallic regions of the DUT by applying UV light from a UV light source to the dispensed UV-curable conductive adhesive.

Example 9 includes the method of any of examples 1-8, wherein dispensing a UV-curable conductive adhesive between the conductive element and the electrical connection point of the DUT is: dispensing an acrylic-based UV-curable conductive adhesive between said conductive element and said electrical connection point of said DUT.

Example 10 includes a test probe tip having a conductive element conductively bonded to a Device Under Test (DUT) having an electrical connection point by a process comprising: positioning the conductive element of the test probe tip proximate to the electrical connection point of the DUT; dispensing a UV-curable conductive adhesive between said conductive element and said electrical connection point of said DUT, said dispensed UV-curable conductive adhesive continuously covering at least a portion of said conductive element and at least a portion of said electrical connection point of said DUT; and bonding the dispensed UV-curable conductive adhesive to the conductive elements and the electrical connection points of the DUT by applying UV light from a UV light source to the dispensed UV-curable conductive adhesive.

Example 11 includes the test probe tip of example 10 engaged to a DUT, wherein dispensing a UV-curable conductive adhesive between the conductive element and the electrical connection point of the DUT comprises: distributing a z-axis conductive UV-curable adhesive between the conductive element and the electrical connection point of the DUT.

Example 12 includes the test probe tip engaged to a DUT of any of examples 10-11, wherein dispensing a UV-curable conductive adhesive between the conductive element and the electrical connection point of the DUT comprises: dispensing an acrylic-based UV-curable conductive adhesive between said conductive element and said electrical connection point of said DUT.

Example 13 includes the test probe tip engaged to a DUT of any of examples 10-12, wherein the dispensed UV-curable conductive adhesive is also continuously covering at least a portion of a non-metallic area of the DUT, and wherein engaging the dispensed UV-curable conductive adhesive to the electrically conductive element and the electrically connection point of the DUT by applying UV light from a UV light source to the dispensed UV-curable conductive adhesive is: bonding the dispensed UV-curable conductive adhesive to the conductive elements, the electrical connection points of the DUT, and the non-metallic regions of the DUT by applying UV light from a UV light source to the dispensed UV-curable conductive adhesive.

Example 14 includes the test probe tip of any of examples 10-13 engaged to a DUT, the processing further comprising: applying pressure to the conductive elements and the electrical connection points of the DUT to compress the dispensed UV-curable conductive adhesive during operation of applying UV light from the UV light source.

Example 15 includes the test probe tip engaged to a DUT of any of examples 10-14, wherein dispensing a UV-curable conductive adhesive between the conductive element and the electrical connection point of the DUT comprises: dispensing a UV-curable conductive adhesive between the conductive element and the electrical connection point of the DUT, the UV-curable conductive adhesive having a viscosity between about 50,000 centipoise and about 75,000 centipoise.

Example 16 includes a method of conductively engaging a test probe tip to a Device Under Test (DUT), the method comprising: positioning a first portion of a conductive element proximate to an electrical connection point of the DUT; dispensing a first quantity of UV-curable conductive adhesive between said first portion of said conductive element and said electrical connection point of said DUT, said dispensed first quantity of UV-curable conductive adhesive continuously covering at least a portion of said first portion of said conductive element and at least a portion of said electrical connection point of said DUT; bonding the dispensed first quantity of UV-curable conductive adhesive to the first portion of the conductive element and the electrical connection point of the DUT by applying UV light from a UV light source to the dispensed first quantity of UV-curable conductive adhesive; positioning a second portion of a conductive element proximate to an electrical connection point of the test probe tip; dispensing a second quantity of UV-curable conductive adhesive between the second portion of the conductive element and the electrical connection point of the test probe tip, the dispensed second quantity of UV-curable conductive adhesive continuously covering at least a portion of the second portion of the conductive element and at least a portion of the electrical connection point of the test probe tip; and bonding the dispensed second quantity of UV-curable conductive adhesive to the second portion of the conductive element and the electrical connection points of the test probe tip by applying UV light from the UV light source to the dispensed second quantity of UV-curable conductive adhesive.

Example 17 includes the method of example 16, wherein applying UV light from a UV light source to the dispensed first quantity of UV-curable conductive adhesive includes: applying UV light from a UV light source having a wavelength between about 365 nanometers and about 460 nanometers to the dispensed first quantity of UV-cured conductive adhesive for a duration between about twenty-five seconds and about thirty-five seconds.

Example 18 includes the method of any one of examples 16-17, wherein applying UV light from a UV light source to the dispensed second quantity of UV-curable conductive adhesive includes: applying UV light from a UV light source having a wavelength between about 365 nanometers and about 460 nanometers to the dispensed second quantity of UV-cured conductive adhesive for a duration between about twenty-five seconds and about thirty-five seconds.

Example 19 includes the method of any one of examples 16-18, the operation of engaging the dispensed first quantity of UV-curable conductive adhesive further comprising: heat is applied from a heat source to the dispensed first quantity of UV-curable conductive adhesive.

Example 20 includes the method of example 19, wherein applying heat from a heat source to the first quantity of dispensed UV-curable conductive adhesive includes: applying heat from a heat source to the dispensed first quantity of UV-curable conductive adhesive for a duration of between about twenty-five seconds and about thirty-five seconds, the heat having a temperature of less than about 200 degrees Celsius.

Example 21 includes the method of any one of examples 16-20, the operation of engaging the dispensed second quantity of UV-curable conductive adhesive further comprising: heat is applied from a heat source to the dispensed second quantity of UV-curable conductive adhesive.

Example 22 includes the method of example 21, wherein applying heat from a heat source to the second quantity of dispensed UV-curable conductive adhesive includes: applying heat from a heat source to the dispensed second quantity of UV-curable conductive adhesive for a duration of between about twenty-five seconds and about thirty-five seconds, the heat having a temperature of less than about 200 degrees Celsius.

Example 23 includes the method of any one of examples 16-22, further comprising: applying pressure to the first portion of the conductive element and the electrical connection point of the DUT to compress the dispensed first amount of UV-curable conductive adhesive during operation of applying UV light from the UV light source.

Example 24 includes the method of any one of examples 16-23, further comprising: applying pressure to the second portion of the conductive element and the electrical connection points of the test probe tip to compress the dispensed second quantity of UV-curable conductive adhesive during operation of applying UV light from the UV light source.

Example 25 includes the method of any of examples 16-24, wherein distributing a first quantity of UV-curable conductive adhesive between the first portion of the conductive element and the electrical connection point of the DUT is: dispensing a first quantity of a z-axis conductive UV curable adhesive between said first portion of said conductive element and said electrical connection point of said DUT.

Example 26 includes the method of any of examples 16-25, wherein dispensing a second quantity of UV-curable conductive adhesive between the second portion of the conductive element and the electrical connection point of the test probe tip is to: dispensing a second quantity of a z-axis conductive UV curable adhesive between the second portion of the conductive element and the electrical connection point of the test probe tip.

Example 27 includes the method of any of examples 16-26, wherein distributing a first quantity of UV-curable conductive adhesive between the first portion of the conductive element and the electrical connection point of the DUT is: dispensing a first quantity of UV-curable conductive adhesive between said first portion of said conductive element and said electrical connection point of said DUT, said first quantity of UV-curable conductive adhesive having a viscosity between about 50,000 centipoise and about 75,000 centipoise.

Example 28 includes the method of any of examples 16-27, wherein dispensing a second quantity of UV-curable conductive adhesive between the second portion of the conductive element and the electrical connection point of the test probe tip is to: dispensing a second quantity of UV-curable conductive adhesive between the second portion of the conductive element and the electrical connection points of the test probe tip, the second quantity of UV-curable conductive adhesive having a viscosity between about 50,000 centipoise and about 75,000 centipoise.

Example 29 includes the method of any of examples 16-28, wherein the dispensed first quantity of UV-curable conductive adhesive is also continuously covering at least a portion of a non-metallic region of the DUT, and wherein joining the dispensed first quantity of UV-curable conductive adhesive to the first portion of the conductive element and the electrical connection point of the DUT by applying UV light from a UV light source to the dispensed first quantity of UV-curable conductive adhesive is: bonding the dispensed first quantity of UV-curable conductive adhesive to the first portion of the conductive element, the electrical connection points of the DUT, and the non-metallic region of the DUT by applying UV light from a UV light source to the dispensed first quantity of UV-curable conductive adhesive.

Example 30 includes the method of any of examples 16-29, wherein the dispensed second quantity of UV-curable conductive adhesive is also continuously covering at least a portion of the non-metallic area of the test probe tip, and wherein the operation of bonding the dispensed second quantity of UV-curable conductive adhesive to the second portion of the conductive element and the electrical connection points of the test probe tip by applying UV light from a UV light source to the dispensed second quantity of UV-curable conductive adhesive is: bonding the dispensed second quantity of UV-curable conductive adhesive to the second portion of the conductive element, the electrical connection points of the test probe tips, and the non-metallic areas of the test probe tips by applying UV light from a UV light source to the dispensed second quantity of UV-curable conductive adhesive.

Example 31 includes the method of any of examples 16-30, wherein distributing a first quantity of UV-curable conductive adhesive between the first portion of the conductive element and the electrical connection point of the DUT is: dispensing a first quantity of an acrylic-based UV-curable conductive adhesive between the first portion of the conductive element and the electrical connection point of the DUT.

Example 32 includes the method of any of examples 16-31, wherein dispensing a second quantity of UV-curable conductive adhesive between the second portion of the conductive element and the electrical connection point of the test probe tip is to: dispensing a second quantity of an acrylic-based UV-curable conductive adhesive between the second portion of the conductive element and the electrical connection point of the test probe tip.

Example 33 includes a test system, comprising: a test and measurement instrument; and a test probe tip having a conductive element, the test probe tip being conductively bonded to a Device Under Test (DUT) having an electrical connection point by a process comprising: positioning the conductive element of the test probe tip proximate to the electrical connection point of the DUT; dispensing a UV-curable conductive adhesive between said conductive element and said electrical connection point of said DUT, said dispensed UV-curable conductive adhesive continuously covering at least a portion of said conductive element and at least a portion of said electrical connection point of said DUT; and bonding the dispensed UV-curable conductive adhesive to the conductive elements and the electrical connection points of the DUT by applying UV light from a UV light source to the dispensed UV-curable conductive adhesive.

Example 34 includes the test system of example 33, wherein the test and measurement instrument is an oscilloscope.

The previously described versions of the disclosed subject matter have many advantages that are described or will be apparent to those of ordinary skill in the art. Even so, not all of these advantages or features are required in all versions of the disclosed apparatus, systems, or methods.

Additionally, the written description makes reference to specific features. It is to be understood that the disclosure in this specification includes all possible combinations of those specific features. For example, where a particular feature is disclosed in the context of a particular aspect or embodiment, that feature can also be used to the extent possible in the context of other aspects and embodiments.

In addition, when reference is made in this application to a method having two or more defined steps or operations, the defined steps or operations may be performed in any order or simultaneously, unless the context excludes those possibilities.

Furthermore, the term "comprising" and its grammatical equivalents are used in this application to indicate that other components, features, steps, processes, operations, etc. are optionally present. For example, an article that "comprises" or "which comprises" components A, B and C can contain only component A, B and C, or it can contain components A, B and C along with one or more other components.

While specific embodiments have been illustrated and described for purposes of illustration, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure.

Claims (20)

1. A method for acquiring a signal from an encapsulated test point on a device under test, the method comprising:

forming an aperture in the enclosure adjacent the test site, the aperture extending through the enclosure to the test site;

delivering a UV curable conductive adhesive into the hole such that the delivered adhesive contacts the test point;

applying UV light from a UV light source to cure the delivered adhesive; and

the conductive element is connected between the cured adhesive and the test and measurement instrument.

2. The method of claim 1, wherein the encapsulated test site comprises one of: a pin, lead, pin, solder ball, pad, via, or via.

3. The method of claim 1, wherein forming the hole in the enclosure adjacent to the test site comprises drilling a hole in the enclosure.

4. The method of claim 1, wherein forming a hole in the enclosure adjacent to the test point comprises forming a hole through the enclosure at an angle substantially normal to a surface of the test point.

5. The method of claim 1, wherein delivering the UV curable conductive adhesive into the aperture comprises inserting a first end of a tube having a translucent wall into the aperture, the first end of the tube containing a volume of the UV curable conductive adhesive sufficient to contact the test point.

6. The method of claim 5, further comprising loading a volume of the UV curable conductive adhesive into the tube using an injector device.

7. The method of claim 5, wherein the tube comprises a removable portion of a dispenser for the UV curable conductive adhesive.

8. The method of claim 5, wherein the tube comprises two end caps and a predetermined volume of UV curable conductive adhesive.

9. The method of claim 1, wherein applying UV light from the UV light source comprises applying UV light through a tube disposed in the bore, the tube having a first end containing the delivered UV curable electrically conductive adhesive in contact with the test point, a second end protruding from the bore, and a translucent wall configured to act as a UV light pipe to transmit UV light from the second end of the tube to the delivered adhesive.

10. The method of claim 1, further comprising placing the first end of the conductive element into the delivered adhesive prior to applying the UV light to the delivered adhesive.

11. The method of claim 1, wherein the conductive element comprises a wire, a resistive element, or a portion of a probe tip.

12. The method of claim 1, wherein the conductive element comprises a pin having a tip and a tip, wherein the tip contacts the delivered adhesive, the tip being structured to form a probing surface, and wherein connecting the conductive element between the cured adhesive and the test and measurement instrument comprises coupling a probe between the probing surface and an input of the test and measurement instrument.

13. The method of claim 1, wherein the conductive element comprises a connector, and wherein connecting the conductive element between the cured adhesive and the test and measurement instrument comprises connecting a cable between the connector and an input of the test and measurement instrument.

14. The method of claim 1, further comprising acquiring the signal at the test point using a test and measurement instrument.

15. The method of claim 1, wherein the delivered UV curable conductive adhesive is a resistive UV curable conductive adhesive, wherein the conductive element comprises a portion of a probe tip, and wherein the conductive element between the cured adhesive and the test and measurement instrument comprises connecting the test and measurement instrument to the probe tip through the probe such that the resistive UV curable conductive adhesive forms a series tip resistor of the probe.

16. A system for electrically connecting a test and measurement instrument to a test point in a device under test, the system comprising:

a tube containing a predetermined volume of a UV curable conductive adhesive, the predetermined volume being selected based on a diameter of the tube such that the adhesive, when cured, establishes electrical contact between the test point and a conductive element proximate to the test point; and

a hand-held UV light source for enabling a user to direct UV light to cure the adhesive at the test site.

17. The system of claim 16, wherein the tube has a first end, a second end, and a translucent wall, the first end structured to be inserted into an aperture formed in the device to be tested to contact the test point, the second end structured to protrude from the aperture, the translucent wall configured to transmit UV light from the UV light source from the second end to the first end.

18. The system of claim 17, wherein the tube is a first tube having a first diameter, further comprising a second tube having a second diameter different from the first diameter.

19. The system of claim 17, wherein the tube is a first tube comprising a resistive UV curable conductive adhesive having a first bulk resistivity, further comprising a second tube comprising a resistive UV curable conductive adhesive having a second bulk resistivity different from the first bulk resistivity.

20. The system of claim 16, wherein the handheld UV light source comprises a translucent tip structured for directing UV light while the user applies pressure.

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