Resistive Test Probe Tips

Abstract

A test probe tip having a tip component, a resistive element, and a flexible member. The tip component is configured to be electrically connected to a device under test at a first end of the tip component. The resistive element is electrically connected to a second end of the tip component along a signal flow axis. The resistive element is configured to provide electrical impedance to an electrical signal transmitted through the resistive element. The flexible member is configured to allow the tip component to move in a first direction when a mechanical force is applied to the tip component in the first direction and to move the tip component in an opposite second direction when the mechanical force applied to the tip component is removed or reduced. The architecture of the resistive element is also described.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of provisional application no. 62 / 673,793, filed May 18, 2018, which is incorporated into this patent application by this reference. Technical Field

[0003] The present disclosure relates generally to test probes and, more particularly, to probe tips of test probes. Background Art

[0004] Today's engineers are trying to test devices that carry high-speed serial buses. Many of these devices can be identified as, but not limited to, second-generation double data rate (DDR2) synchronous dynamic random access memory (SDRAM), fourth-generation double data rate (DDR4) SDRAM, and Peripheral Component Interconnect Express (PCIe). The amplitude of voltage swings and pulse frequencies is very high and the complexity of the transmitted signals requires precise electrical probing. These and other buses are becoming highly prevalent in various types of consumer hardware devices. There are many test points of interest in each of these products.

[0005] The test points in these products can vary greatly in both geometry and accessibility, typically requiring one or two contact points. Typically, contact points include micro-traces, vias, component pads, and connector contacts that provide electrical contact with, and therefore access to, high-speed signals. However, the test points are not always in the same plane, and if two probing contacts are required at once (as in the case of differential probes), tip compliance may be desirable to assist in positioning the probes for proper contact. Contact points can be located on PCA hardware and at nearly every orientation angle, from vertical to horizontal. In these types of scenarios, the test points are better accessed by probe tips that have flexibility.

[0006] While there are semi-permanent forms of probe contacts for these access points (including soldering of wires to these points), this solution has a number of disadvantages, including potential damage to the device under test (DUT) during connection, long setup times, and the need for exceptional dexterity to solder cables to these test points. Furthermore, semi-permanent contacts do not provide for rapid commissioning. Soldered-in probe tips tend to wear out after only a few connections and thus create the need for replacement, which can be very expensive. Finally, there tends to be high variability in signal fidelity (especially the upper frequency limit of the signal) due to the quality and geometry of the soldered connection.

[0007] Embodiments of the disclosed technology address shortcomings in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is an exploded view of a test probe tip according to an embodiment.

[0009] Figure 2A yes Figure 1 Side view of the test probe tip when assembled. Figure 2B is the edge of the test probe tip Figure 2A A cross-sectional view taken along the line shown in FIG.

[0010] Figure 3 An exemplary test probe tip is shown mounted on an exemplary test probe in accordance with an embodiment.

[0011] Figure 4 An exemplary test probe tip is shown mounted on an exemplary test probe in accordance with an embodiment.

[0012] Figure 5A is a side cross-sectional view of a resistor element according to an embodiment. Figure 5B yes Figure 5A A cross-sectional view of a resistor element taken along a line perpendicular to the signal flow axis of the resistor element.

[0013] Fig. 6A is a side cross-sectional view of a resistor element according to an embodiment. Figure 6B yes Fig. 6A A cross-sectional view of a resistor element taken along a line perpendicular to the signal flow axis of the resistor element.

[0014] The depictions in the drawings are not necessarily to scale. DETAILED DESCRIPTION

[0015] Embodiments of the disclosed technology generally include a probe tip adapted for use with a test probe and configured to provide precise contact with a test point, for example, on a device under test (DUT). Such a test probe tip may be configured as a spring probe including a resistive element or an impedance element positioned almost at the point of contact with the DUT. The resistive element or the impedance element may greatly improve the penetration response of the spring probe and also significantly reduce the DUT loading, thereby enabling high-speed signal acquisition. The spring element or the flexible element may reduce the mechanical load experienced by the test probe tip.

[0016] Test probes and test probe tips according to the disclosed technology can advantageously produce better physical and electrical control over the contact area and also make the test probes and test probe tips well suited for quick commissioning environments that are typically not amenable to long contact setup times. Test probes and probe tips according to the disclosed technology can advantageously provide excellent visibility for connection placement and intuitive operation of various types of products, particularly handheld or quick placement probes.

[0017] Figure 1 is an exploded view showing a portion of a test probe tip 100 according to an embodiment. Figure 2A yes Figure 1 1 is a side view of the assembled test probe tip 100 . Figure 2B is along Figure 2A A cross-sectional view taken along the line shown in FIG. Figure 1 , 2A As shown in FIGS. 2B and 2C , the test probe tip 100 may include a tip component 101, a resistor element 102, a flexible member 103, and a structural member 104. During use, an electrical signal may be obtained by the tip component 101 and transmitted through the resistor element 102, thereby defining a signal flow axis 105 of the test probe tip 100. Figure 2A As shown in , the signal flow axis may be generally aligned with the longitudinal axis of the test probe tip 100 .

[0018] The tip member 101 may have a first end 106 configured to be electrically connected to a device under test 107 (see Figure 3 and Figure 4 ). For example, the tip member 101 may have one or more points for establishing or otherwise facilitating a fine-grain electrical connection with one or more contact points on the DUT 107. The second end 108 is opposite the first end 106 of the tip member 101 along the signal flow axis 105 of the test probe tip 100.

[0019] The resistor element 102 can be electrically coupled to the second end 108 of the tip member 101 at a first end 109 of the resistor element 102 along the signal flow axis 105 of the test probe tip 100. The electrical coupling can be achieved by surface contact, welding, conductive epoxy, or any other suitable method. The resistor element 102 is configured to provide electrical impedance to an electrical signal transmitted through the resistor element 102. The resistor element 102 can also have a second end 110, which is opposite to the first end 109 of the resistor element 102 along the signal flow axis 105 of the test probe tip 100.

[0020] The resistor element 102 may be a conventional resistor element, or the resistor element 102 may be a dedicated resistor element, such as a resistor element for FIG. 5A to FIG. 6B These resistor elements are discussed below. If the resistor element 102 is a conventional resistor element, the resistor element may be, for example, a 0402 package style resistor with a variable air gap or even no air gap.

[0021] The resistive element 102 may be or include a conductive epoxy resistor having a suspended resistive material. The conductive epoxy may be formed, for example, within a tube that is not adhered to the epoxy. The tube may be, for example, made of polytetrafluoroethylene (PTFE), such as PTFE provided by the TEFLON® brand. The amount of resistive material suspended within the conductive epoxy may be increased or decreased to achieve a desired amount of resistance. Additionally, or alternatively, the resistance value provided by the resistive element 102 may be adjusted by removing material from the resistive element 102 (such as, for example, using a conventional diamond saw or laser) while monitoring the resulting resistance value.

[0022] The resistive element 102 may be or include an elastomer having a suspended resistive material. The elastomer may be formed, for example, within a tube that is not adhered to the elastomer. The tube may be, for example, made of polytetrafluoroethylene (PTFE), such as PTFE provided under the TEFLON® brand. The amount of resistive material suspended within the elastomer may be increased or decreased to achieve a desired amount of resistance value for the resistive element 102. Additionally, or alternatively, the resistance value provided by the resistive element 102 may be adjusted by removing material from the resistive element 102 (such as, for example, using a conventional diamond saw or laser) while monitoring the resulting resistance value.

[0023] Such an elastomeric resistor element may be assembled by compressing the elastomer between the tip component 101 and the plunger base component 114 and then bonding or otherwise securing the structural member 104 in place to ensure that the elastomer remains in a compressed state, which will impart some resistive properties to the elastomer. The amount of resistance may be measured while the elastomer is compressed to ensure that the desired amount of resistance is obtained.

[0024] Instead of or in addition to the resistive element 102, embodiments may include a resistive epoxy used to attach the tip assembly 101 to the DUT 107, thereby providing a resistor between the test probe tip 100 and the DUT 107. In this scenario, the resistive aspect of the epoxy may be determined based on various calibration techniques.

[0025] The flexible member 103 may be configured to allow the tip member 101 to move in a first axial direction 111 when a mechanical force is applied to the tip member 101 in a first axial direction 111 along the signal flow axis 105 of the test probe tip 100. For example, the mechanical force may be caused by the tip member 101 of the test probe tip 100 contacting the DUT 107. The flexible member 103 may also be configured to allow the tip member 101 to move in a second axial direction 112 along the signal flow axis 105 of the test probe tip 100 when the mechanical force applied to the tip member 101 is removed or reduced. The second axial direction 112 is opposite to the first axial direction 111.

[0026] Not all embodiments of the disclosed technology will include the flexible member 103. In such embodiments, the resistive element 102 may be connected to the test probe body 113 (see Figure 3 and Figure 4 ), such as a probe body described below.

[0027] The flexible member 103 may further include a plunger base component 114 , a spring mechanism 115 , and a barrel component 116 .

[0028] The plunger base member 114 can be electrically coupled to the second end 110 of the resistor element 102 at a first end 117 of the plunger base member 114. The electrical coupling can be achieved by surface contact, welding, conductive epoxy, or any other suitable method. The second end 118 of the plunger base member 114 is opposite to the first end 117 of the plunger base member 114 along the signal flow axis 105 of the test probe tip 100. The second end 118 of the plunger base member 114 can be configured to slide inside the barrel member 116 and slide along the signal flow axis 105 of the test probe tip 100.

[0029] The barrel 116 may have a spherical end, such as Figure 1 and Figure 2A The spherical shape can, for example, facilitate the insertion of the barrel-shaped member 116 into the test probe 120 (see Figure 3 and Figure 4 ) within a receiving receptacle. Even so, the barrel-shaped member 116 need not have a spherical end in all embodiments; other configurations may also be used.

[0030] The spring mechanism 115 may be at least partially within the barrel member 116. The spring mechanism 115 may be configured to allow the plunger base member 114 to move in the first axial direction 111 within the barrel member 116 when a mechanical force is applied to the tip member 101 in the first axial direction 111. The spring mechanism 115 may also be configured to move the plunger base member 114 in the barrel member 116 in the second axial direction 112 when the mechanical force is removed or reduced. The spring mechanism 115 may be, for example, a helical compression spring, such as in Figure 1 Thus, the helical compression spring can be compressed when a mechanical force is applied to the tip component 101 along the first axial direction 111 and expand when the mechanical force is removed or reduced. As another example, the spring mechanism 115 can be an elastic disk or a pressure disk, or a torsion spring.

[0031] The structural member 104 can structurally couple the tip component 101 to the plunger base component 114, and the resistive element 102 can be within the structural member 104. Because the resistive element 102 itself may not have sufficient structural integrity, the structural member 104 can transmit all or a portion of the mechanical force applied to the tip component 101 to the flexible member 103. The structural member 104 can be mechanically coupled to the plunger base component 114 and to the tip component 101 by adhesive, epoxy, retaining screws, or any other suitable chemical or mechanical fastener. The structural member 104 can be constructed of a non-conductive material, such as plastic. Although the structural member 104 is depicted as a void-free structure, in embodiments, the structural member 104 can include pores, such as, for example, holes or openings.

[0032] In an embodiment, the inner diameter of the structural member 104 is larger than the outer diameter of the resistor element 102 to ensure an air gap 119 between the resistor element 102 and the structural member 104. Figure 2B An example of this configuration is shown in . The air gap 119 can help ensure that the structural member 104 does not affect the electrical properties of the resistive element 102. The size of the air gap 119 (specifically, the distance between the outer diameter of the resistive element 102 and the inner diameter of the structural member 104) can be selected based on the configuration of the test probe tip 100 or the signal captured by the test probe tip 100 and can therefore vary depending on the desired implementation.

[0033] Figure 3 An exemplary test probe tip 100 is shown mounted on an exemplary test probe 120. Figure 3 As shown in FIG. 1 , the single-tip test probe 120 may include a test probe tip 100 mounted on a test probe body 113. The test probe 120 may be, for example, a test probe of a test and measurement device. By, for example, placing a barrel-shaped member 116 (see FIG. 1 ) Figure 1and Figure 2A ) into a receiving receptacle of the test probe 120, the test probe tip 100 may be mounted on the exemplary test probe 120. The receiving receptacle may, for example, be soldered to a flexible circuit that is part of the test probe 120.

[0034] Thus, the test probe 120 can obtain an electrical signal from the DUT 107 by positioning the tip member 101 of the test probe tip 100 over a target area of ​​the DUT 107. Thus, for example, a user can use the test probe 120 to generate a compression resistance between the test probe tip 100 and a test point on the DUT 107, such as, for example, a high-speed signal access point.

[0035] Figure 4 An exemplary test probe tip 100 is shown mounted on an exemplary test probe 121. Figure 4 As shown in FIG. 1 , the dual-tip differential test probe 121 may include two test probe tips 100 mounted on a test probe body 113. The test probe 121 may be, for example, a test probe of a test and measurement device. The test probe 121 may be, for example, a barrel-shaped component 116 (see FIG. 1 ). Figure 1 and Figure 2A ) is inserted into a receiving socket of the test probe 121 to mount each of the test probe tips 100 on the exemplary test probe 121. The receiving socket can be, for example, soldered to a flexible circuit that is part of the test probe 121.

[0036] Thus, the test probe 121 can obtain a differential electrical signal from the device under test by positioning the tip portion 101 of each test probe tip 100 on a target area of ​​the device under test. Thus, for example, a user can use the test probe 121 to generate a compression resistance between one of the test probe tips 100 and a test point on the DUT 107 (or between two test probe tips 100 and two test points), the test point being, for example, a high-speed signal access point.

[0037] Figure 5A 1 is a partial cross-sectional view showing a side portion of a portion of a resistor element 122 according to an embodiment. The cross section is taken along a cutting plane parallel to a signal flow axis 132 of the resistor element 122. Figure 5A The resistor element 122 may be, for example Figure 1 The resistor element 122 is provided. Figure 5B yes Figure 5A FIG. 1 is a cross-sectional view of the resistor element 122 taken along a cutting plane perpendicular to the signal flow axis 132 of the resistor element 122. During use, an electrical signal is transmitted through the resistor element 122 in the direction of the signal flow axis 132. Figure 5A As shown in FIG, the signal flow axis 132 can be generally aligned with the longitudinal axis of the resistive element 122. When the resistive element 122 is a test probe tip (such as Figures 1 to 2B When the resistive element 122 is a portion of the test probe tip 100 , the signal flow axis 132 of the resistive element 122 can be substantially aligned with the signal flow axis 105 of the test probe tip 100 .

[0038] like Figure 5A and Figure 5B As shown in , the resistor element 122 may include a first layer 123 having a first impedance and a second layer 124 having a second impedance. The second impedance may be greater than the first impedance, and the first layer 123 and the second layer 124 may be concentric. Here, "concentric" means having a common center. The layers (first layer 123 and second layer 124) may be regular polygons, rectangles, circles, or other shapes with an identifiable center point in the cross section, wherein the cross section is perpendicular to the signal flow axis 132 of the resistor element 122.

[0039] In an embodiment, such as in Figure 5B , the second layer 124 surrounds the first layer 123. In other embodiments, the first layer 123 surrounds the second layer 124. In an embodiment, the second impedance of the second layer 124 can be much greater than the first impedance of the first layer 123, so that the second layer 124 is substantially an insulator.

[0040] As in Figure 5A and Figure 5B As shown in , the resistor element 122 may also include a third layer 125 having a third impedance that is greater than the second impedance. The first layer 123, the second layer 124, and the third layer 125 may be concentric. In a cross section perpendicular to the signal flow axis 132 of the resistor element 122, the second layer 124 may surround the first layer 123 and the third layer 125 may surround the second layer 124. Therefore, the impedance value of the layer may be increased from the innermost layer to the outermost layer. Because higher frequencies travel further from the center of the resistor, a configuration in which the impedance value of the layer increases from the innermost layer to the outermost layer will enable the direct current (DC) and low frequency (LF) components of the signal to be transmitted through the center of the resistor element 122 having a relatively small resistance value, while the high frequency components of the signal will be subject to an increased resistance value.

[0041] In other embodiments, the impedance value of the layers may decrease from the innermost layer to the outermost layer. In still other embodiments, the impedance value of the middle layer may be higher than the impedance values ​​of the two adjacent layers.

[0042] The resistor element 122 may include a metal layer 126. The metal layer 126 may include any suitable material for making electrical connections to the plunger base component 114 and the tip component 101. Such materials may include silver, gold, copper, or any other suitable conductive material, or any combination of these materials. The metal layer 126 may be applied using any suitable process, such as a micropenning process. The metal layer 126 may be formed as a cap, or the metal layer 126 may be formed so that either end (or both ends) of the resistor layer is exposed.

[0043] Although Figure 5A and Figure 5B Three concentric resistor layers are depicted, more or fewer resistor layers are also within the scope of the present disclosure. In particular, any resistor having two or more resistor layers is readily contemplated.

[0044] Fig. 6A 1 is a partial cross-sectional view showing a side portion of a portion of a resistor element 127 according to an embodiment. The cross section is taken along a cutting plane parallel to a signal flow axis 132 of the resistor element 127. Fig. 6A The resistor element 127 may be, for example Figure 1 The resistor element 102 is provided. Figure 6B yes Fig. 6A FIG. 1 is a cross-sectional view of the resistor element 127 taken along a cutting plane perpendicular to the signal flow axis 132 of the resistor element 127 through an exemplary second layer 129 of the resistor element 127. During use, an electrical signal is transmitted through the resistor element 127 in the direction of the signal flow axis 132. As shown in FIG. Fig. 6A As shown in FIG. 1 , the signal flow axis 132 can be generally aligned with the longitudinal axis of the resistive element 127. When the resistive element 127 is a test probe tip (such as Figures 1 to 2B When the resistive element 127 is a portion of the test probe tip 100 , the signal flow axis 132 of the resistive element 127 can be substantially aligned with the signal flow axis 105 of the test probe tip 100 .

[0045] As in Fig. 6A and Figure 6B As shown in FIG. 1 , the resistive element 127 may include a first layer 128 having a first impedance and second layers 129, 133 having a second impedance. The second impedance may be greater than the first impedance, and the first layer 128 and the second layer 129, 133 may be orthogonal to the signal flow axis 132 of the resistive element 127. The second layers 129, 133 may be non-conductive.

[0046] In an embodiment, the second layer 129, 133 may include a through hole 130 that passes through the second layer 129, 133. The through hole 130 may be parallel to the signal flow axis 132 of the resistive element 127, and the through hole 130 may be plated with a conductive material or filled with a conductive material. In an embodiment, the second layer 129, 133 may have more than one through hole 130. The through hole or multiple through holes 130 may be located at different distances from the signal flow axis 132 (such as at Fig. 6A The through-holes 130 may be configured to allow the electrical signal to be transmitted through the respective second layers 129, 133 to the next layer. Such a configuration may, for example, enable the DC and LF components of the electrical signal to be transmitted through the second layers 129, 133 substantially unimpeded, while the high frequency components of the electrical signal are forced to jump from one layer to the next, thereby slowing down the high frequency components of the electrical signal. For example, the high frequency components may be capacitively coupled to the next conductive layer.

[0047] As in Fig. 6A and Figure 6B As shown in FIG. 1 , the resistive element 127 may also include a third layer 131 orthogonal to the signal flow axis 105 of the test probe tip 100. The third layer 131 has a third impedance lower than the second impedance. In an embodiment, the first impedance (of the first layer 128) and the third impedance (of the third layer 131) may be equal. The second layer 129, 133 may be between the first layer 128 and the third layer 131. Both the first layer 128 and the third layer 131 may be conductive. As shown in FIG. Fig. 6A and Figure 6B As shown in the exemplary embodiment of , there may be alternating conductive layers (first layer 128 and third layer 131 ) and non-conductive layers (second layers 129 , 133 ). FIG. 6A to FIG. 6B The example of is just one possible implementation of alternating the layers.

[0048] The conductive layer may be or include any suitable conductive material. Such material may include silver, gold, copper or any other suitable conductive material, or a combination of any of these conductive materials. The non-conductive layer may be or include any suitable insulating material, such as, for example, plastic.

[0049] Example

[0050] Illustrative examples of the disclosed technology are provided below. Embodiments of the technology may include one or more and any combination of the examples described below.

[0051] Example 1 includes a test probe tip, which includes: a tip component having a first end and a second end, the first end being configured to be electrically connected to a device under test, the second end being opposite to the first end of the tip component along a signal flow axis of the test probe tip; a resistor element being electrically connected to the second end of the tip component along the signal flow axis, the resistor element being configured to provide electrical impedance to an electrical signal transmitted through the resistor element; and a flexible member being configured to allow the tip component to move along a first axial direction when a mechanical force is applied to the tip component in a first axial direction along the signal flow axis of the test probe tip, and to cause the tip component to move in a second axial direction along the signal flow axis of the test probe tip when the mechanical force applied to the tip component is removed or reduced, the second axial direction being opposite to the first axial direction.

[0052] Example 2 includes the test probe tip described in Example 1, wherein the resistor element is electrically connected to the second end of the tip component at the first end of the resistor element, wherein the flexible member includes a plunger base component, the plunger base component is electrically connected to the second end of the resistor element, and the second end of the resistor element is opposite to the first end of the resistor element along the signal flow axis of the test probe tip.

[0053] Example 3 includes the test probe tip of any of Examples 1-2, further comprising a structural member that structurally couples the tip component to the flexible member.

[0054] Example 4 includes the test probe tip of Example 3, wherein the resistive element is located within the structural member.

[0055] Example 5 includes the test probe tip described in any one of Examples 1 to 4, wherein the plunger base component is electrically connected to the second end of the resistor element at the first end of the plunger base component, wherein the flexible member also includes a barrel-shaped component, and wherein the second end of the plunger base component is configured to slide inside the barrel-shaped component and slide along the signal flow axis of the test probe tip, and the second end of the plunger base component is opposite to the first end of the plunger base component along the signal flow axis of the test probe tip.

[0056] Example 6 includes the test probe tip of any one of Examples 1 to 5, wherein the flexible member further comprises a spring mechanism within the barrel-shaped component, the spring mechanism being configured to allow the plunger base component to move within the barrel-shaped component along the first axial direction when the mechanical force is applied to the tip component along the first axial direction and to move the plunger base component within the barrel-shaped component along the second axial direction when the mechanical force is removed or reduced.

[0057] Example 7 includes the test probe tip of any of Examples 1 to 6, wherein the resistive element includes a first layer having a first impedance and a second layer having a second impedance greater than the first impedance.

[0058] Example 8 includes the test probe tip of any of Examples 1 to 7, wherein the first layer and the second layer are concentric.

[0059] Example 9 includes the test probe tip of any of Examples 1 to 8, wherein the second layer surrounds the first layer in a cross section perpendicular to the signal flow axis of the test probe tip.

[0060] Example 10 includes the test probe tip of any one of Examples 1 to 9, wherein the resistive element further includes a third layer having a third impedance that is greater than the second impedance, wherein the first layer, the second layer, and the third layer are concentric, and wherein, in a cross-section perpendicular to the signal flow axis of the test probe tip, the second layer surrounds the first layer and the third layer surrounds the second layer.

[0061] Example 11 includes the test probe tip of any of Examples 1 to 7, wherein the first layer and the second layer are orthogonal to the signal flow axis of the test probe tip.

[0062] Example 12 includes the test probe tip of Example 11, wherein the second layer is non-conductive and includes a via through the second layer, the via being parallel to the signal flow axis of the test probe tip.

[0063] Example 13 includes the test probe tip of any one of Examples 11 to 12, further comprising a third layer orthogonal to the signal flow axis of the test probe tip, the third layer having a third impedance lower than the second impedance, the second layer being between the first layer and the third layer, and the first layer and the third layer being both conductive.

[0064] Example 14 includes the test probe tip of any of Examples 1 to 13, wherein the resistive element comprises a material selected from the group consisting of a conductive epoxy resistor with a suspended resistive material or an elastomer with a suspended resistive material.

[0065] Example 15 includes a resistive element configured to provide electrical impedance to an electrical signal transmitted along a signal flow axis of the resistive element, the resistive element comprising: a first layer having a first impedance; and a second layer having a second impedance, the second impedance being greater than the first impedance.

[0066] Example 16 includes the resistive element of Example 15, wherein the first layer and the second layer are concentric.

[0067] Example 17 includes the resistive element of any of Examples 15 to 16, wherein the second layer surrounds the first layer in a cross section perpendicular to the signal flow axis.

[0068] Example 18 includes the resistive element of any of Examples 15 to 16, wherein, in a cross-section perpendicular to the signal flow axis, the first layer surrounds the second layer, and wherein the second layer is substantially an insulator.

[0069] Example 19 includes the resistive element of any one of Examples 15 to 17, wherein the resistive element further includes a third layer having a third impedance greater than the second impedance, wherein the first layer, the second layer, and the third layer are concentric, and wherein, in a cross-section perpendicular to the signal flow axis, the second layer surrounds the first layer and the third layer surrounds the second layer.

[0070] Example 20 includes the resistive element of Example 15, wherein the first layer and the second layer are orthogonal to the signal flow axis.

[0071] Example 21 includes the resistor element of Example 20, wherein the second layer is non-conductive and includes a via through the second layer, the via being parallel to the signal flow axis.

[0072] Example 22 includes the resistive element described in any one of Examples 20 to 21, further comprising a third layer orthogonal to the signal flow axis, the third layer having a third impedance lower than the second impedance, the second layer being between the first layer and the third layer, and the first layer and the third layer being both conductive.

[0073] Embodiments may operate on specially created hardware, on firmware, digital signal processors, or on a specially programmed general-purpose computer including a processor that operates according to programming instructions. The term "controller" or "processor" as used herein is intended to include microprocessors, microcomputers, ASICs (application-specific integrated circuits), and dedicated hardware controllers. One or more aspects may be embodied in computer-usable data and computer-executable instructions, such as in one or more program modules, which are executed by one or more computers (including monitoring modules) or other devices. In general, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types when executed by a processor in a computer or other device. Computer executable instructions may be stored on non-transient computer-readable media, such as hard disks, optical disks, removable storage media, solid-state memory, RAM (random access memory), etc. As will be appreciated by those skilled in the art, the functionality of program modules may be combined or distributed as needed in various embodiments. Furthermore, the functionality may be embodied in whole or in part in firmware or hardware equivalents, such as integrated circuits, field programmable gate arrays (FPGAs), etc. Certain data structures may be used to more efficiently implement one or more aspects of the disclosed systems and methods, and such data structures are contemplated to be within the scope of the computer-executable instructions and computer-usable data described herein.

[0074] The previously described variations of the disclosed subject matter have many advantages that are either 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 variations of the disclosed apparatus, system or method.

[0075] In addition, this written description refers to specific features. It is to be understood that the disclosure in this specification includes all possible combinations of these specific features. For example, where a specific feature is disclosed in the context of a particular aspect or embodiment, the feature may also be used in the context of other aspects and embodiments to the extent possible.

[0076] Furthermore, when reference is made herein 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 such possibilities.

[0077] In addition, the term "comprising" and its grammatical equivalents are used in this application to mean that other components, features, steps, processes, operations, etc. may optionally exist. For example, an article that "comprising" or "which includes" components A, B, and C may include only components A, B, and C, or the article may include components A, B, and C and one or more other components.

[0078] Although particular embodiments have been shown and described for purposes of illustration, it will be appreciated that various modifications may be made without departing from the spirit and scope of the present disclosure. Therefore, the present invention should be limited only by the appended claims.

Claims

1. A test probe tip, comprising: a tip member having a first end configured to be electrically connected to a device under test and a second end opposite the first end of the tip member along a signal flow axis of the test probe tip; a resistive element electrically connected to the second end of the tip member along the signal flow axis, the resistive element being configured to provide an electrical impedance to an electrical signal transmitted through the resistive element; a flexible member configured to allow the tip member to move in a first axial direction when a mechanical force is applied to the tip member in a first axial direction along the signal flow axis of the test probe tip and to move the tip member in a second axial direction along the signal flow axis of the test probe tip when the mechanical force applied to the tip member is removed or reduced, the second axial direction being opposite to the first axial direction; a structural member structurally coupling the tip member to the flexible member; as well as an air gap between the structural member and the resistive element; The resistor element includes a first layer having a first impedance and a second layer having a second impedance, the second impedance is greater than the first impedance, the first layer and the second layer are concentric, and in a cross section perpendicular to the signal flow axis of the test probe tip, the second layer surrounds the first layer.

2. The test probe tip of claim 1, wherein: The resistor element is electrically connected at a first end of the resistor element to the second end of the tip component, wherein the flexible member includes a plunger base component, which is electrically connected to the second end of the resistor element, and the second end of the resistor element is opposite to the first end of the resistor element along the signal flow axis of the test probe tip.

3. The test probe tip of claim 1, wherein: The resistive element is within the structural member.

4. The test probe tip of claim 2, wherein: The plunger base component is electrically coupled to the second end of the resistor element at the first end of the plunger base component, wherein the flexible member further comprises a barrel-shaped component, and wherein the second end of the plunger base component is configured to slide inside the barrel-shaped component and along the signal flow axis of the test probe tip, the second end of the plunger base component being opposite to the first end of the plunger base component along the signal flow axis of the test probe tip.

5. The test probe tip of claim 4, wherein: The flexible member also includes a spring mechanism within the barrel-shaped component, the spring mechanism being configured to allow the plunger base component to move within the barrel-shaped component in the first axial direction when the mechanical force is applied to the tip component in the first axial direction and to move the plunger base component within the barrel-shaped component in the second axial direction when the mechanical force is removed or reduced.

6. The test probe tip of claim 1, wherein: The resistive element further includes a third layer having a third impedance greater than the second impedance, wherein the first layer, the second layer, and the third layer are concentric, and wherein, in a cross-section perpendicular to the signal flow axis of the test probe tip, the second layer surrounds the first layer and the third layer surrounds the second layer.

7. The test probe tip of claim 1, wherein: The first layer and the second layer are orthogonal to the signal flow axis of the test probe tip.

8. The test probe tip of claim 7, wherein: The second layer is non-conductive and includes a via through the second layer, the via being parallel to the signal flow axis of the test probe tip.

9. The test probe tip of claim 8, further comprising a third layer orthogonal to the signal flow axis of the test probe tip, the third layer having a third impedance lower than the second impedance, the second layer being between the first layer and the third layer, and the first layer and the third layer being both conductive.

10. The test probe tip of claim 1, wherein: The resistive element comprises a material selected from the group consisting of a conductive epoxy resistor with a suspended resistive material or an elastomer with a suspended resistive material.

11. A resistive element configured to provide electrical impedance to an electrical signal transmitted along a signal flow axis of the resistive element, the resistive element comprising: a first layer having a first impedance; as well as A second layer having a second impedance greater than the first impedance, wherein the first layer and the second layer are concentric, the second layer surrounds the first layer in a cross section perpendicular to the signal flow axis, and wherein the second layer is substantially an insulator.

12. The resistor element according to claim 11, wherein The resistive element also includes a third layer having a third impedance, the third impedance being greater than the second impedance, wherein the first layer, the second layer, and the third layer are concentric, and wherein, in a cross-section perpendicular to the signal flow axis, the second layer surrounds the first layer and the third layer surrounds the second layer.

13. The resistor element according to claim 11, wherein The first layer and the second layer are orthogonal to the signal flow axis.

14. The resistor element according to claim 13, wherein The second layer is non-conductive and includes a via through the second layer, the via being parallel to the signal flow axis.

15. The resistor element of claim 14, further comprising a third layer orthogonal to the signal flow axis, the third layer having a third impedance lower than the second impedance, the second layer being between the first layer and the third layer, and the first layer and the third layer being both conductive.

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