Patent Publication Number: US-2019187179-A1

Title: Portable Electrical Testing Device with Electrical Probe and Laser Soldering Device

Description:
BACKGROUND 
     This disclosure generally relates to electrical testing probes for testing electronic circuits, and particularly, to improved testing probes that enable efficient soldering of a probe to a location in an electrical circuit. 
     Commercially generated electrical circuits are generally subjected to electrical testing to ensure quality and reliability of the circuit. Conventionally, testing of electrical circuits on printed circuit boards (PCB) may be performed using browser-style or solder-in probes. Browser probes allow engineers to quickly measure electrical signals in specific locations in a circuit by contacting a probe tip to a desired location in the circuit and by applying mechanical pressure to the probe tip to ensure a good electrical connection is made between the probe tip and the electrical circuit. Such hand-held probes, however, are not ideal for measurements that require the probe to be held in place for a significant amount of time or for measurements in hard-to-reach locations of the circuit in question. 
     In such circumstances, solder-in probes may be used because they allow the person carrying out a testing procedure to simply solder the probe in place before the measurement is performed. A disadvantage of conventional solder-in probes is that, generally, the device under test (DUT) often is required to be powered off when attaching the solder-in probe. For a system that requires several verification measurements, soldering and de-soldering probes to and from various locations within a PCB is a time-consuming and error-prone process. 
     SUMMARY 
     The disclosed embodiments overcome several drawbacks associated with conventional electrical testing probes by using laser radiation to efficiently solder and de-solder test probes, thereby significantly reducing time required to perform electrical measurements of electrical circuits. 
     In this regard, a portable electrical testing device is disclosed. The portable electrical testing device includes an electrical probe and a laser soldering device. The electrical probe is configured to be placed in contact with an electrical circuit element and to receive electrical signals from the circuit element. The laser soldering device is configured to apply laser radiation to the electrical probe while the probe is in contact with the electrical circuit element. The applied laser radiation heats the electrical probe and enables soldering of the electrical probe to the electrical circuit element to thereby form a mechanical bond between the electrical probe and the circuit element. 
     The electrical probe may further include a surface coating of an electrically conductive fusible metal alloy. The electrically conductive fusible metal alloy is configured to be heated by receiving radiation from the laser soldering device and to thereby be melted, when the electrical probe is in contact with the electrical circuit element. Upon cooling in the absence of radiation from the laser, the electrically conductive fusible metal alloy is configured to solidify and to thereby form a mechanical bond between the electrical probe and the circuit element. The electrical probe may further include a replaceable probe lead including the electrically conductive fusible metal alloy as a surface coating. 
     The portable electrical testing device may further include an electrical sensor that determines when the electrical probe is in electrical contact with an electrical circuit element. The portable electrical testing device may further include a safety mechanism that enables operation of the laser soldering device only when the electrical probe is determined by the sensor to be in contact with the electrical circuit element. The portable electrical testing device may further include a pressure sensor that determines when a pressure is applied between the electrical probe and the electrical circuit element. A further safety mechanism may enable operation of the laser soldering device only after a predetermined time duration during which the electrical probe has been in electrical contact with the electrical circuit element, and pressure has been applied between the electrical probe and the electrical circuit element. 
     The portable electrical testing device may further include an accelerometer that determines three-dimensional accelerations of the electrical probe. A further safety mechanism may enable operation of the laser soldering device only when accelerations of the electrical probe are determined by the accelerometer to be below a predetermined threshold. 
     A method of operating a portable electrical testing device is also disclosed. The method includes placing an electrical probe of the portable electrical testing device in contact with an electrical circuit element. The method further includes activating a laser soldering device of the portable electrical testing device to cause laser radiation to be transmitted to and to be received by the electrical probe while the probe is in contact with the electrical circuit element. The laser radiation received from the laser soldering device heats the electrical probe and enables soldering of the electrical probe to the electrical circuit element thereby forming a mechanical bond between the electrical probe and the circuit element. 
     The method may further include causing the laser radiation to be transmitted to and to be received by a replaceable probe lead on the electrical probe that includes a surface coating of an electrically conductive fusible metal alloy. The surface coating of an electrically conductive fusible metal alloy then melts upon heating from laser radiation received from the laser soldering device and flows to thereby make simultaneous contact with the electrical circuit element and the electrical probe. Upon cooling in the absence of laser radiation, the electrically conductive fusible metal alloy solidifies to form the mechanical bond between the electrical probe and the circuit element. 
     Further embodiments, features, and advantages, as well as the structure and operation of the various embodiments, are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various embodiments of the invention and, together with the general description of the invention given above, and the detailed description of the embodiments given below, explain the embodiments of the invention. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. 
         FIG. 1  is a schematic illustration of a portable electrical testing device that includes electrical probes and corresponding laser soldering devices, according to an embodiment. 
         FIG. 1A  provides a detailed view of the first probe, the second probe, the first adjustable mounting device, and the second adjustable mounting device, of  FIG. 1 , according to an embodiment. 
         FIG. 2  is a schematic illustration of the first and second probes of  FIG. 1 , which each contain an electrical probe and corresponding laser soldering device, according to an embodiment. 
         FIG. 3  is a schematic illustration of an electrical probe having internal circuitry including various sensors and safety mechanisms, according to an embodiment. 
         FIG. 4  is flowchart providing an overview of a method of using a portable electrical testing device, according to an embodiment. 
         FIG. 5  is flowchart illustrating further details of a method of using a portable electrical testing device, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure provides electrical testing probes that may be soldered in place within a circuit using a portable, hand-held, electrical testing device that includes an electrical probe and a laser soldering device integrated within a single apparatus. The disclosed electrical testing device applies laser radiation to heat an isolated area within contact of an electrical probe or to a nearby region, and feeds solder to join the electrical probe to a point of contact within an electrical circuit to be tested. The disclosed embodiments: eliminate the use of separate tools for soldering and electrical testing, reduce the need to transport the device under test (DUT), and reduce time spent in configuring the DUT for testing, thereby providing a more efficient probing technique. 
       FIG. 1  is a schematic illustration of a portable electrical testing device  100  that includes electrical probes and corresponding laser soldering devices, according to an embodiment. The portable electrical testing device  100  may have a body  102  that provides a mechanical housing for one or more electrical testing probes. In this example, the portable electrical testing device  100  includes a first probe  104   a  and a second probe  104   b . The first probe  104   a  may be mounted to the mechanical housing  102  with a first adjustable mounting device  106   a . The second probe  104   b  may be mounted to the mechanical housing  102  with a second adjustable mounting device  106   b . The adjustable mounting devices,  106   a  and  106   b , may mount the electrical probes to the mechanical housing  102  in a way that enables the first  104   a  and second  104   b  probes to be adjustably positioned relative to the mechanical housing  102 . 
       FIG. 1A  provides a detailed view of the first probe  104   a , the second probe  104   b , the first adjustable mounting device  106   a , and the second adjustable mounting device  106   b . In this example, the adjustable mounting devices,  106   a  and  106   b , allow the first probe  104   a  and the second probe  104   b  to be adjustably positioned in a plane parallel to the plane of  FIGS. 1 and 1A . As shown, the first adjustable mounting device  106   a  and the second adjustable mounting device  106   b  enable an angular displacement  108  of the first  104   a  probe relative to the second  104   b . In certain embodiments, the first probe  104   a  may be adjustably positioned independently of the second probe  104   b . For example, the first probe  104   a  may be positioned according to an angular displacement  108  while the second probe  104   b  is held fixed. Similarly, the second probe  104   b  may be positioned with an angular displacement  108  while the first probe  104   a  is held fixed. 
     In further embodiments, the first  104   a  and second  104   b  probes may be positioned according to an angular displacement  108  in a concerted fashion. For example, the first  104   a  and second  104   b  probes may move toward one another with an angular displacement  108 . In a further example, the first  104   a  and second  104   b  probes may move away from one another with an angular displacement  108 . 
     The portable electrical testing device  100  may further include a first mechanical adjustment device  110   a  that may be adjusted by a user. Adjustment of the first mechanical adjustment device  110   a  may impart a mechanical displacement to the first probe  104   a . Similarly, portable electrical testing device  100  may further include a second mechanical adjustment device  110   b  that may be adjusted by a user. Adjustment of the second mechanical adjustment device  110   b  may impart a mechanical displacement to the second probe  104   b . For example, the first  110   a  and second  110   b  mechanical adjustment devices may include a knob, a lever, or other mechanical actuator. 
     As described in greater detail below (with reference to  FIG. 2 ), the first  104   a  and second  104   b  probes are composite structures containing an electrical probe  202  and corresponding laser soldering device  206 . The electrical probe  202  is configured to be placed in contact with an electrical circuit element and is configured to receive electrical signals from the circuit element. The portable electrical testing device  100  further includes a first electrical lead  112   a  and a second electrical lead  112   b . First  112   a  and second  112   b  electrical leads receive electrical signals from the first  104   a  and second  104   b  probes and provided the received signals to an external measurement device (not shown). The external measurement device may be a voltage meter, a current meter, an oscilloscope, etc. The composite structures of probes  104   a  and  104 , each containing an electrical probe  202  and corresponding laser soldering device  206 , are described in greater detail below with reference to  FIG. 2 . 
       FIG. 2  is a schematic illustration of the first  104   a  and second  104   b  probes of  FIG. 1 , which each contain an electrical probe  202  and corresponding laser soldering device  206 , according to an embodiment. 
     The first probe  104   a  includes an electrical probe  202   a  with an electrically conducting tip  204   a . Similarly, the second probe  104   b  includes an electrical probe  202   b  with an electrically conducting tip  204   b . The first probe  104   a  includes a laser soldering device  206   a , with a lens  208   a , that provides laser radiation  210   a  to the electrically conducting tip  204   a . Similarly, the second probe  104   b  includes a laser soldering device  206   b , with a lens  208   b , that provides laser radiation  210   b  to the electrically conducting tip  204   b . The laser radiation,  210   a  and  210   b , projected respectively by laser soldering devices,  206   a  and  206   b , provides heat to electrically conducting tips,  204   a  and  204   b , respectively. The laser radiation,  210   a  and  210   b , received by electrically conducting tips,  204   a  and  204   b , causes the electrically conducting tips,  204   a  and  204   b , to be heated sufficiently to enable soldering of the electrically conducting tips,  204   a  and  204   b , to desired locations within an electrical circuit to be tested. 
     According to an embodiment, each of electrically conducting tips,  204   a  and  204   b , may be provided with a surface coating of an electrically conductive fusible metal alloy (not shown). The fusible metal alloy on each of the electrically conducting tips,  204   a  and  204   b , may be configured to be heated by receiving radiation from a respective laser soldering device,  206   a  and  206   b , and to thereby be melted, when the respective electrical probe tips,  204   a  and  204   b , are in contact with corresponding electrical circuit elements to be tested. The fusible metal alloy on each of the electrically conducting tips,  204   a  and  204   b , may be further configured to solidify and thereby form a mechanical bond between the electrically conducting tips,  204   a  and  204   b , and the corresponding circuit elements upon cooling in the absence of radiation from respective laser soldering devices,  206   a  and  206   b.    
     As described above, a mechanical housing  102  is provided which physically supports the first  104   a  and second  104   b  probes. Each of first  104   a  and second  104   b  probes may be provided with respective first  106   a  and second  106   b  adjustable mounting devices that enable the first  104   a  and second  104   b  probes to be adjustably positioned relative to the mechanical housing  102 . In a further embodiment, each of the adjustable mounting devices,  106   a  and  106   b , enable the electrical probes,  202   a  and  202   b , and the laser soldering devices,  206   a  and  206   b , to be adjustably positioned relative to the mechanical housing  102 . 
     In a further embodiment, the adjustable mounting devices,  106   a  and  106   b , enable the electrical probes,  202   a  and  202   b , and the laser soldering devices,  206   a  and  206   b , to be adjustably positioned relative to the mechanical housing  102  while maintaining a fixed positional relative orientation between each of the electrical probes,  202   a  and  202   b , and each respective laser soldering device,  206   a  and  206   b.    
     The embodiments described above refer to embodiments in which the mechanical housing  102  supports two probes,  104   a  and  104   b . Other embodiments, however, may have only a single probe with corresponding electrical probe and laser soldering device. Still further embodiments may include one or more additional electrical probes with one or more corresponding laser soldering devices mounted to a mechanical housing using adjustable mounting devices. Further, the adjustable mounting devices may enable the one or more additional electrical probes and the one or more corresponding laser soldering devices to be adjustably positioned relative to the mechanical housing. 
       FIG. 3  is a schematic illustration of an electrical probe  300  having internal circuitry including various sensors and safety mechanisms, according to an embodiment. Electrical probe  300  may be similar to probes  202   a  and  202   b  discussed above. Electrical probe  300  may include an electrical sensor  302  that determines when an electrically conducting probe tip  304  of the electrical probe  300  is in electrical contact with an electrical circuit element (not shown). Electrical probe  300  may further include a safety mechanism  306  that enables operation of the laser soldering device (not shown in this figure) only when the electrical probe tip  304  of the electrical probe  300  is determined by the sensor  302  to be in contact with the electrical circuit element. Electrical probe  300  may further include a processing circuit  308  that receives an electrical control signal from the safety mechanism  306 . Based on a value of the electrical control signal received from the safety mechanism  306 , the processing circuit  308  may control transmission of electrical signals received from the electrically conductive probe tip  304  to external leads  310   a  and  310   b.    
     In a further embodiment, electrical probe  300  may further include a pressure sensor  312  that determines when a pressure is applied between the electrically conducting probe tip  304  of the electrical probe  300  and the electrical circuit element. Electrical probe  300  may further include a safety mechanism  314  that enables operation of the laser soldering device (not shown) only if certain conditions have been met. The safety mechanism  314  may communicate with safety mechanism  306  and may provide electrical control signals to the processing circuit  308 . In this regard, safety mechanism  314  may only enable operation of electrical probe  300  after a predetermined time duration during which: ( 1 ) the electrically conducting probe tip  304  of the electrical probe  300  has been in electrical contact with the electrical circuit element, as determined by the sensor  302 , and ( 2 ) during which pressure has been applied between the electrically conducting probe tip  304  the electrical probe  300  and the electrical circuit element, as determined by the pressure sensor  312 . 
     The processing circuit  308  may be configured to receive an electrical control signal from the safety mechanism  314  in addition to safety mechanism  306 . Further, based on a value of the electrical control signal received from the safety mechanisms  306  and  314 , the processing circuit  308  may control transmission of electrical signals received from the electrically conductive probe tip  304  to external leads  310   a  and  310   b.    
     In a further embodiment, electrical probe  300  may further include a laser activation device  316 . The laser activation device  316  may be a switch or other electro-mechanical device that receives input from a user and generates an activation signal. The laser activation device  316  may be a conventional electro-mechanical switch that is activated by receiving a mechanical stimulus from a user. In further embodiments, laser activation device  316  may an optical or electrical device that detects a user&#39;s touch. For example, laser activation device  316  may be a touch sensor that generates a signal in response to detecting a user&#39;s touch. Electrical probe  300  may further include a safety mechanism  318  that enables operation of the laser soldering device only for a predetermined time duration after the laser activation device  316  has received input from a user and generated a signal that is provided to safety mechanism  318 . 
     The processing circuit  308  may be configured to receive an electrical control signal from the safety mechanism  318  in response to receiving an activation signal from the laser activation device  316 . Further, based on a value of the electrical control signal received from the safety mechanism  318 , the processing circuit  308  may control transmission of electrical signals received from the electrically conductive probe tip  304  to external leads  310   a  and  310   b.    
     According to an embodiment, electrical probe  300  may further include an accelerometer  320  that determines three-dimensional accelerations of the electrical probe  300 . Electrical probe  300  may further include a safety mechanism  322  that enables operation of the laser soldering device only when accelerations of the electrical probe are determined by the accelerometer  320  to be below a predetermined threshold. 
     The processing circuit  308  may be configured to receive an electrical control signal from the accelerometer  320  and/or from the safety mechanism  322  in response to accelerations of the electrical probe  300  that are detected by the accelerometer  320 . Further, based on a value of the electrical control signal received from the safety mechanism  322 , the processing circuit  308  may control transmission of electrical signals received from the electrically conductive probe tip  304  to external leads  310   a  and  310   b.    
       FIG. 4  is flowchart  400  providing an overview of a method of using a portable electrical testing device such as those illustrated in  FIGS. 1 and 2 , according to an embodiment. 
     In stage  402 , the method includes placing an electrical probe of the portable electrical testing device in contact with an electrical circuit element. In stage  404  the method includes activating a laser soldering device of the portable electrical testing device. This action causes laser radiation to be transmitted to, and to be received by, an electrical probe while the probe is in contact with the electrical circuit element. In stage  406 , the method includes heating of the electrical probe by the received radiation which enables soldering of the electrical probe to the electrical circuit element. In stage  408 , the method includes forming an electrical and mechanical bond between the electrical probe and the circuit element. This is achieved when the heated electrical probe causes solder to melt and to flow between the heated probe and the circuit element, and upon cooling, the solder solidifies to form an electrical and mechanical bond between the electrical probe and the circuit element. In stage  410 , the method includes causing the electrical probe that has been mechanically bonded to the circuit element to receive electrical signals from the circuit element. 
       FIG. 5  is flowchart  500  illustrating further details of a method of using a portable electrical testing device, according to an embodiment. The method starts at stage  502 . In stage  504 , the method may include a replacing a probe tip  304  (see  FIG. 3 ) that has a surface coating of the electrically conductive fusible metal alloy. Stage  506  may include aligning one or more probe tips (e.g.,  304  of  FIGS. 3 , or  104   a  and  104   b  of  FIGS. 1, 1A, and 2 ) to place the one or more probe tips in contact with a circuit element (or “via”). The probe tips may be positioned manually or by actuating one or more mechanical adjustment device (e.g. mechanical adjustment device  110   a  and  110   b  of  FIG. 1 ). As described above, the adjustable mounting devices may be configured to maintain a fixed positional relative orientation between each electrical probe (e.g.,  204   a  and  204   b ) and corresponding laser soldering device (e.g.,  206   a  and  206   b ). 
     In stage  508 , the method includes invoking a safety mechanism to only activate the laser soldering device if a safety trigger is engaged (e.g., laser activation device  316  of  FIG. 3 ). In stage  510 , the method includes determining whether the safety trigger has been engaged. In stage  512 , upon determining that the safety trigger is engaged, the method proceeds to stage  516 . In stage  512 , when the safety trigger is determined to not be engaged, the method returns to stage  508 . 
     In stage  516 , a pressure sensor may determine that a pressure is applied between the electrical probe and the electrical circuit element for a predetermined time duration. In this example, the predetermined time duration may be one second. In other embodiments, the predetermined time duration may take on any other value as dictated by design choice. In stage  518 , the method includes determining whether a pressure is applied between the electrical probe and the electrical circuit element. In stage  520 , upon determining that a pressure is applied between the electrical probe and the electrical circuit element, the method proceeds to stage  524 . In stage  522 , when a pressure is determined to not be applied between the electrical probe and the electrical circuit element the method returns to stage  516 . 
     In stage  524 , an accelerometer may determine three-dimensional accelerations of the electrical probe. In stage  526 , the method includes determining whether the electrical probe is being held in a stable condition. For example, in stage  528 , when a measured acceleration is determined to be below a predetermined threshold, the method proceeds to stage  532 . In stage  530 , the method may include determining that accelerations are above a predetermined threshold and, therefore, that the electrical probe is not being held in a stable condition. In this situation, at stage  530 , the method returns to stage  524 . 
     At stage  532 , the method includes activating the laser soldering device while the laser activation device  316  is activated (e.g., while a button is pressed) for a time sufficient to heat and thereby melt the electrically conductive fusible metal alloy (e.g., solder). In stage  534 , the method may include determining whether the laser soldering device has been activated for a time greater than a predetermined time limit. In stage  536 , the method may include determining that the predetermined time limit has been exceeded. In this situation, the method proceeds to stage  540  in which the laser soldering device is deactivated, thus ending the method in stage  542 . In stage  538 , the method may include determining that the predetermined time limit has not been exceeded. In this situation, the method may return to stage  534  with the laser soldering device continuing to be activated until predetermined time limit is exceeded in stage  536 . 
     As described above, the method may further include other operations to ensure safety of operation. For example, an electrical sensor may be used to determining when the electrical probe is in electrical contact with an electrical circuit element. Further, the method may include enabling operation of the laser soldering device, by a safety mechanism, only when the electrical probe is determined by the sensor to be in contact with the electrical circuit element 
     The Summary and Abstract sections may set forth one or more but not all example embodiments and thus are not intended to limit the scope of embodiments of the invention and the appended claims in any way. 
     Embodiments have been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined to the extent that the specified functions and relationships thereof are appropriately performed. 
     The foregoing description of specific embodiments will so fully reveal the general nature of embodiments of the invention that others can, by applying knowledge of those of ordinary skill in the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of embodiments of the invention. Therefore, such adaptation and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for description and not of limitation, such that the terminology or phraseology of the specification is to be interpreted by persons of ordinary skill in the relevant art considering the teachings and guidance presented herein. 
     The breadth and scope of embodiments of the invention should not be limited by any of the above-described example embodiments, but should be defined only in accordance with the following claims and their equivalents 
     The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.