Abstract: A bond head is provided for a wire bonding machine having a linear axis frame, a rotary axis frame, a bond tool and a wire clamp. The linear axis frame is vertically linearly displacable along a linear axis, while the rotary axis frame is rotationally displacable along a rotary axis. A pivotal connector is provided which pivotally connects the rotary axis frame to the linear axis frame, enabling the rotary axis frame to rotate independent of linear displacement of the linear axis frame. The bond tool is connected to the rotary axis frame and is vertically linearly displacable in response to vertical linear displacement of the linear axis frame and rotationally displacable in response to rotational displacement of the rotary axis frame. The wire clamp is connected to the linear axis frame and is vertically linearly displacable in response to vertical linear displacement of the linear axis frame, while the wire clamp is maintained rotationally stationary during rotational displacement of the rotary axis frame.

Abstract: A wire bond monitoring system for monitoring wire bonds made on layered packages includes a technique for accessing both the die and the laminate package and making electrical contact thereto so as to test the continuity of the wire bond connection. An electrical connection can be made to a metal trace between the die and the laminate package by contacting a via extending downwardly through the package. Alternatively, a contact may be made from above using a flexible contact. The flexible contact may be attached to the wire bond clamp.

Abstract: The invention relates to a process for welding electric conductors employing ultrasound following compaction. The process comprises compaction of the conductors in a compaction area by adjusting height and width up to a preset contact force and ultrasonically welding according to predetermined, stored parameters.

Abstract: A solder bump forming method includes a step of causing one end surface of a punch inserted into a through hole provided in a die to be retracted by a desired distance from an end surface of the die to thereby provide a recess of a desired volume in the end surface of the die, a step of embedding solder in the recess of the die, a step of moving the punch toward the end surface of the die to thereby extrude the solder, and a step of fusing the solder extruded by the movement of the punch.

Abstract: A method enabling controlled selective heating of workpiece components during microwave brazing. Two workpiece components are joined by melting an adhesion interlayer material between the two components. An indication of when the interlayer has melted is provided. The temperature difference across the braze assembly is monitored and adjusted via a feedback loop to reduce stresses in the braze joint resulting in a stronger braze joint.

Abstract: A method of pressure bonding a bumped electronic part using: a tilting mechanism which tiltably supports a suction tool for sucking a bumped electronic part; and locking means for inhibiting a tilting operation of the tilting mechanism. The method includes: a suction step of sucking the bumped electronic part to the suction tool; a step of detecting the position of the bumped electronic part which is sucked to the suction tool, and positioning the bumped electronic part with respect to a substrate, under a state where the tilting operation is inhibited; and a pressure bonding step of pressure bonding bumps of the bumped electronic part which is sucked to the suction tool, to the substrate under a state where the tilting operation is enabled. According to this arrangement, the tilting mechanism is not accidentally swung during the positioning operation, and hence the mounting accuracy is prevented from being impaired.

Abstract: A method for determining the quality of a weld bead includes producing a weld bead along a work surface during a welding process and scanning the weld bead with a vision system to obtain positional data points for defining a weld bead profile. The weld bead has a weld toe zone or region, which is formed at the interface between the weld bead and the work surface. A curve fit is determined for the weld bead profile bases on the positional data points obtained by the laser scan vision system. The toe radius is derived bases on the curve fit and is then compared to a first predetermined limit and a second predetermined limit, greater than the first predetermined limit, to determine the quality of the weld bead. If the toe radius is less than the first predetermined limit or greater than the second predetermined limit, the welding process is modified to produce a weld bead with a toe radius that falls within the desired range.

Abstract: Process and device for the friction welding of workpieces that consist of different materials or possess different material properties, especially different hardnesses and/or melting points. The workpieces are rotated over a limited angle of rotation of less than 1,080.degree., preferably 290.degree. to 430.degree., relative to one another during the friction process. The angle of rotation is controlled via the friction time and the switching off of the rotating drive. The more resistant workpiece is preferably rotated and is leveled off on its face before the friction welding.

Abstract: A non-destructive method for identifying off-composition solder columns of for example, a ceramic column grid array. The method is performed at the ceramic module level prior to card assembly to avoid costly loss or rework post card assembly. The assembly of solder columns on a substrate is heated to a temperature below the melting temperature of pure-composition solder and above the temperature of attachment of a solder column to an organic board. Heating the assembly produces visually detectable changes characteristic of off-composition solder which are used for identifying which solder columns are composed of off-composition solder.

Abstract: In a BGA package having electrically connected active balls and electrically disconnected dummy balls, the active balls are positioned in a radial direction at intervals of 90.degree. around the dummy balls. When a defect occurs in a solder joint, the package can be easily repaired by finding defective active ball; forming a repair hole by using a cutting means at a predetermined portion of the printed circuit board corresponding to a central position between the dummy ball and the defectively soldered active ball; inserting a solder paste injector into the repair hole to inject solder thereinto; and mutually connecting pad extensions of the dummy ball and the defective active ball with the injected solder. Therefore, the overall process can be simplified and its reliability can be improved.

Abstract: Aluminum-lithium alloy sheets which are welded together are examined to identify regions requiring repair. A grid is applied to the sheet about the region requiring repair, and the region to be repaired is ground out and rewelded. Residual stresses are relieved by planishing yes to cause localized plastic deformation in the repaired region. The grid is used as a guide to restoring the original dimensions of the sheet in a manner which tends to reduce in-plane shrinkage. The reduced in-plane shrinkage in turn tends to reduce undesired tensile residual stresses. The planishing also tends to work-harden the weld filler.

Abstract: A method for correcting the welding path of a welding torch which weaves from side to side while proceeding along the welding path is disclosed. The method comprises the steps of: determining the center of weaving of the welding torch with respect to a welding center line, by monitoring the arc current which varies according to the change of distance between the welding end of the welding torch and a welding surface; and correcting the center of weaving of the welding torch to a correction position on the welding center line, when the center of weaving of the welding torch is misaligned with the welding center line by a predetermined distance, in which the direction of weaving of the welding torch is corrected to be perpendicular to an imaginary line connecting the most recent two correction positions among the correction positions of the center of weaving.

Abstract: A method for leak testing of a hermetic package closure comprises the steps of: creating a pocket in a lid; plating the lid; placing solder in the pocket; melting the solder in the pocket; drilling a hole through the solder and the plated lid creating an unplated area on the plated lid; testing the hermetic package closure for leaks through the hole; heating the solder reflow, wherein surface tension of the solder over the hole and the unplated area enable the solder to form a hermetic closure.

Abstract: A device and method is available for detecting abnormalities of an electric discharge generated for forming a ball at the end of a bonding wire in a bonding apparatus. A high voltage is applied across the bonding wire and an electrode, and the maximum value of the applied high voltage is detected and sent, via a peak hold circuit, to a computer that compares the maximum high voltage with an insulation breakdown voltage of a normal detection range and calculates a gap between the end of the bonding wire and the electrode, thus determining the discharge abnormalities based upon the result of the calculation of the gap.

Abstract: An apparatus for measuring the height of a solder wave having a supporting horizontal member, at least one elongated pin slidably affixed to the horizontal member extending vertically downward. The elongated pins have a sensing means affixed to it and the sensing means communicate with and indicator means to notify a technician the height of a solder wave relative to the top surface of the solder pot. The elongated pins with sensors attached thereto are set up to notify a technician if the solder wave is too low, too high, or at an optimum level. A screw and nut provide height adjustment for the elongated pins.

Abstract: The present invention relates to controls for a multi-zone reflow oven. In the present invention a plurality of infra red thermal scanners are located at critical points along the path which a substrate passes in a reflow oven so as to generate an actual solder paste time/temperature profile as a substrate passes through the zones of the reflow oven. The actual temperature of the solder paste is determined at critical zones for generating feedback control signals. The time/temperature profile is stored for transfer to a different reflow oven so as to effect the identical solder paste time/temperature curve on the same or a different oven.

Abstract: Device and method for aligning bandsaw blade strip ends prior to welding, comprising at least six displacement sensors disposed on a welding apparatus for measuring locations of two strip ends relative to a reference line, a microcomputer which calculates, from the sensor measurements, the position, direction and curvature of each strip end at the weld line, and a display showing whether the difference of position and direction between the strip ends is within predetermined limits.

Abstract: An apparatus and method are available for detecting the presence of inert gas in an enclosure isolating one side of selected weld structures being joined during welding operation. The system and method include using an inert gas detector relying upon an electric filament positioned in a separate containment connected to the first containment in order to determined whether the required purity level of inert gas has been achieved in the weld enclosure.

Abstract: A method is available for inspecting a printed circuit board and solder paste deposited upon the printed circuit board, whereby both systematic defects occurring during a solder paste deposition process and random defects are located. The printed circuit board is continuously scanned by an inspection head immediately following the solder paste deposition process. Images of the printed circuit board are then analyzed for random defects such as missing solder paste, improper solder paste coverage, and solder bridging. Next, heights of solder paste deposits are sampled. A pattern of light is projected upon selected solder paste deposits, and images of the selected solder paste deposits are captured. Light triangulation techniques are then used for determining the height of each selected solder paste deposit. Variations in the height of solder paste are systematic defects occurring in the solder paste deposition process.

Abstract: It is an object of the present invention to provide a method and an apparatus for soldering inspection of a surface mounted circuit board, which can improve an inspection accuracy by obtaining a highly accurate X-rays transmission image corresponding to a real shape of the mounted surface.

Abstract: A new test method to quantify capillary flow solderability on a printed wiring board surface finish. The test is based on solder flow from a pad onto narrow strips or lines. A test procedure and video image analysis technique were developed for conducting the test and evaluating the data. Feasibility tests revealed that the wetted distance was sensitive to the ratio of pad radius to line width (l/r), solder volume, and flux predry time.

Abstract: The composition of a hard-facing welding material to be overlaid onto a cast iron base metal followed by a supercooling treatment for hardening must lie above a line LA in a Schaeffler's structure diagram which is represented by a Cr equivalent and a Ni equivalent. On the other hand, if the base metal is preheated, the carbon precipitation line will be at the Ni equivalent of 34 (LC1), and the Cr equivalent will thus be above 4. However, if the Cr equivalent is above 4, there will occur cracks after welding (examples in which cracks occurred are shown by square marks represented by a in FIG. 1). As a solution, the carbon precipitation line was raised up to the Ni equivalent of 38 without preheating the base metal, and the Cr equivalent of the welding material was made to be 4 or less.

Abstract: A process for preparing tubular coupons formed of a pair of tube lengths butt-welded together with a full depth circumferential weld includes partially diagonally cutting the coupon sample through its transverse dimension so as to leave a thin bending strip along one wall of the coupon about which the coupon is bent for inspection of the internal surface of the weld area. Two procedures are described, both of which leave the interior surface of the weld exposed adjacent the diagonal cutting line through the coupon. The procedure facilitates bending open the cut coupon for internal inspection of the weld area. A jig fixture for holding the coupon during cutting by a band saw blade is described.

Abstract: A wire bonding apparatus includes a frame, an X, Y, table, installed on the frame, including a linear stepping motor with a first stator and a first inductor, a transducer, pivotably installed on the X, Y table, to one end of which a capillary for bonding wire is installed, a first transferring portion installed to the frame to make the other end of the transducer ascend so that the capillary for wire bonding ascends, a second transferring portion installed on the X, Y table in front of the first transferring portion to, thereby, make the other end of the transducer ascend during bonding, and a first location detecting portion installed to the frame and the X, Y table to detect an amount of movement in the X and Y directions so that energy loss according to the driving of a head portion can be reduced.

Abstract: A method for analyzing solder joint assemblies in devices such as solder bumped silicon chips, ball grid arrays or land grid arrays is disclosed. The method includes applying a dye solution to a device under test and then causing that dye solution to penetrate any interstices between any solder interconnect and the device under test, which also includes penetrating any fractures in any joints or joint failures. Next, the dye is dried or cured so as to provide ready analysis upon the analysis portion of the method. The device under test is then caused to be separated or fractured in such a way that a seam or border of a solder joint or an attachment border may be analyzed to identify any structural failure by visually analyzing where any dye has penetrated such structural failures.

Abstract: In a soldering ball mounting apparatus, a pickup head is movable between a soldering ball feeder and a workpiece to be mounted with soldering balls. The pickup head has a bottom formed with a large number of absorber holes for vacuum-absorbing the soldering balls from the soldering ball feeder. On the way to the workpiece, light is irradiated onto the bottom of the pickup head from the exterior. When the light leaks into the pickup head, the leakage light is detected by a light detector provided in the pickup head so that presence of a soldering-ball pickup error is determined. On the other hand, on the way to the soldering ball feeder after mounting the soldering balls onto the workpiece, light is irradiated along the bottom of the pickup head from one side. Accordingly, when the light is not received at the opposite side, at least one soldering ball remains attached to the bottom of the pickup head so that presence of a soldering-ball mounting error is determined.

Abstract: A method for determining the generation of a diffusion bond between two articles is disclosed. The two articles are sealed together to define a cavity therebetween. A vacuum is drawn in the cavity by means of an evacuation tube having a passageway. The passageway is then sealed and the articles are subjected to a temperature and pressure to diffusion bond the articles together. A successful diffusion bond can be determined if the evacuation tube sidewall is collapsed.

Abstract: A hidden lead package device is configured to be placed between a leadless component such as a surface mount package (SMP) used to house a SAW device and a standard printed circuit board configured for solder joints in a leadless contact with the printed circuit board. The hidden lead device is made using materials having similar characteristic thermal expansion properties as that of the SMP and printed circuit board pads to which the hidden lead is affixed. The hidden lead extends across the underside of the SMP along the PCB surface. One end of the lead is brazed to an SMP pad and the opposite end is soldered to a communicating PCB pad. The brazing temperature is higher than the reflow temperature for the solder. The hidden lead device causes the relative movement between the leadless carrier and the printed circuit board to occur along a length of the hidden lead and thus minimizes tensional or compressive forces to the solder joints.

Abstract: A device making it possible to carry out wettability measurements under a controlled atmosphere, comprising an apparatus (5) for measuring the wettability of at least one surface portion of a sample by a liquid metallic solder, at least partially included in an enclosure (6) which includes a gas injector which comprises at least one set of ducts (10) mounted in series and/or in parallel, at least one portion of which includes gas injection orifices, and is fed by at least one gas supply pipe connected to the set at a primary connection node, the dimensioning of the set respecting the following relationship:.SIGMA..omega..sub.i /.SIGMA..phi..sub.i .gtoreq.1 preferably.gtoreq.1.5;where .SIGMA..omega..sub.i represents the sum of the internal cross sections of the gas supply pipes which feed the set and .SIGMA..phi..sub.i represents the sum of the cross sections of the gas injection orifices of the set of ducts.

Abstract: Apparatus and method is provided for separating electrical connections, such as, solder connections, between two surfaces in which electrical connections are relatively weak and thus can be readily separated. The preferred application of the disclosed process and apparatus is its use in separating semiconductor devices from its device carrier after the devices have been through burn-in tests. The unique process and apparatus allows multiple uses of device carrier for testing and/or burning-in devices.

Abstract: Soldering condition information such as the position and angle of a soldering iron, amount of solder supplied and heating time is stored beforehand, for each grouping of parts, in a part classification table (26) for soldering purposes. Parts to be mounted on a board are stored, in correspondence with the board ID, on a floppy disk of a floppy disk device (24). When the board ID is entered, the parts to be mounted on the board are displayed on a display unit (23). The operator reads out the part classification table (26) for soldering purposes and designates soldering correction information that corresponds to the part groups to which the parts belong. As a result, a teach-data table (27) in which soldering condition information has been stored in correspondence with the parts is created. Soldering is executed automatically in accordance with the teach-data table (27).

Abstract: In a wave solder manufacturing process, a test device is used to measure the contact-area between a solder wave and a printed wiring board. In particular, the test device is a printed wiring board (PWB) that includes at least two arrays of electrical contacts, one array near each side of the PWB. As the PWB makes contact with a solder wave, the number of electrical contacts in each array that are grounded by the solder wave are counted and displayed on an alpha-numeric display mounted on top of the PWB. This "distance-based" measurement provides an accurate determination of the uniformity of the contact-area, and concomitantly the dwell-time of the soldering process.

Abstract: A method and apparatus are available for detecting the remaining amount of bonding wire on a wire spool of a wire bonder using a cam and detector switch so as to detect the number of revolutions of the wire spool which feeds out the bonding wire. A device for judging whether or not the number of revolutions detected by the detector switch has reached a preset number is linked to the detector switch. When the detected number of revolutions of the wire spool reaches the preset number, the rotation of the motor is stopped so as to stop the feed out of the wire.

Abstract: A method and kit for precisely placing fine pitch surface-mount electronic components onto printed circuit boards. An alignment substrate having a pattern of solder pads and holes or transverse edges corresponding to the pattern of solder pads and holes or edges on a printed circuit board is secured to a base by registration pins fastened to the base and inserted into contact with said holes or edges. Generally, the alignment substrate is preferably another circuit board identical with the board to be bonded to the electrical component. A template having a pattern of recesses corresponding to the component lead pattern is secured over the alignment substrate. A component is placed on the template with leads in the recesses. The component is lifted away, a printed circuit board is placed over the template and the component is lower onto the board. The board with component in place can then be removed for soldering.

Abstract: A process and system exists for temperature control and testing of modules, such as printed circuit boards, with fitted electronic, electromechanical and mechanical components or individual components, wherein the modules are subjected, following assembly in a soldering process and when the solder joints are still in a semi-molten state, to one or more test phases at high and low temperature, in order to detect defects at an early stage and to take immediate corrective measures when errors occur. To this end, in a first test phase the modules are cooled, as they emerge from the soldering process, to a temperature ranging from 40.degree. to 125.degree. C. and tested in a first test phase. Thereafter, in a second test phase the modules are cooled to a temperature ranging from -40.degree. to 10.degree. C. and tested. In the respective test phase the modules are subjected to a component and/or function test in order to determine defective modules.

Abstract: A process of making brazed monolayer abrasive tools wherein the braze alloy and abrasive particles are applied to the tool form and the weight of each material is monitored after each application step to determine the weight of each of these materials which is applied to the tool form to more precisely control the bond height and diamond concentration in the finished tool product. The weight of each material applied to the tool is compared to a predetermined target weight after the individual steps of applying the material. If the amount of either material applied to the tool falls outside selected limits of the weight target, the tool assembly may be rejected at that stage of the process. Only tools which successfully pass the comparison step are further processed and introduced to the fusion for step braze bonding the alloy and abrasive particles to the tool. This permits the tool components from rejected tools to be recovered and recycled if desired.

Abstract: A fast, nondestructive, and easy to perform method of Potentiometric Evaluation of Substrate Oxidation ("PESO") is provided. A coated part to be analyzed is placed in contact with an electrolytic solution having a pH adjusted to provide an optimum oxide dissolution rate. The open circuit potential of the part is monitored as the substrate oxide dissolves in the electrolytic solution. The voltage typically changes as a function of time during oxide dissolution. When oxide dissolution is complete, the voltage reaches a steady value associated with active dissolution of the substrate metal and reduction processes on the coating. The electrolytic solution can be flowed or agitated to reduce concentration polarization, provide more meaningful voltage measurements, and minimize the time required for analysis. The time required to reach a steady-state voltage provides a measure of the amount of substrate oxide within pores in the coating.

Abstract: A method of bond quality monitoring wherein a bonding machine is fitted with a touchdown mechanism including a pair of contacts (23, 24), which normally open upon touchdown of a bonding tool (27) raised and lowered by a bond head carriage (13). As the tool (27) is lowered towards a bonding surface (31), the bonding machine's computer (61) performs a test (103) to sense production of a touchdown signal produced by opening of the contacts (23, 24). If touchdown is sensed, the carriage (13) proceeds to an overtravel position. Upon reaching the overtravel position, a second test (108) is performed to confirm touchdown, and energy is then applied to the bond site. During energy application, the logic state of the touchdown mechanism is checked to ensure that the contacts do not close for example to check for application of inadequate force during bonding. If a contact closure is sensed, the bond site location is logged for further examination such as a nondestructive pull test.

Abstract: A method for forming a bump on a semiconductor device takes advantage of the solderability difference of the solder paste applied to a solder pad in order to form a bump, so that it does not require an etching process. In addition, a pre-test of the semiconductor device can be carried out in a state that the solder pad is united with a BLM layer, so as to prove out semiconductor devices of good quality in advance of finishing the formation of the bump and the semiconductor devices of good quality can be applied with a subsequent process.

Abstract: A method of testing a filler material to be used in an arc welding process, the method comprising the steps of providing first and second test plates, the first test plate having a generally planar surface, and the second test plate having opposed, parallel, generally planar surfaces and a beveled edge forming a generally planar beveled surface extending at an angle from one of the opposed surfaces and forming a generally planar land which extends between the beveled surface and the other of the opposed surfaces and which extends generally perpendicular to the opposed surfaces, placing the land in abutment with the first plate surface, providing a restraining fillet weld at the junction of the other surface of the second plate and the first plate surface, and using the filler material to provide a test fillet weld at the junction of the beveled surface and the first plate surface.

Abstract: An ultrasonic bonding apparatus comprises an ultrasonic wave controller, a bonding system including a bonding head, a laser oscillator, a laser optics, a vibration monitoring system including a vibrometer, and a mechanism for feeding a result of monitoring back to a bonding condition.

Abstract: Method of positioning an object on a carrier, device suitable for carrying out this method, and suction tube suitable for use in the device.The method is for laser soldering of an electronic component (7) on a pc-board (1). The component is positioned on a contact face (3) of the pc-board (1) by a device comprising a vibration transducer (53, 69, 85) which is brought into mechanical hard contact with the component (7) while the component is held against the pc-board. Subsequently, a laser (205, 207) heats solder present on the contact face and vibrations generated by the laser in the solder are passed on to the vibration transducer while the mechanical hard contact is being maintained. The vibration transducer then checks for the presence of mechanical contact between the object and the carrier and/or the melting of the solder from a comparatively strong decrease in the vibration amplitude during melting of the solder.

Abstract: Apparatus for assessing solderability of electronic component leads and printed wiring boards by sequential electrochemical reduction. The apparatus detects and quantifies the oxides present on copper, solder, andintermetallics that are detrimental to solderability. A solderable portion of the component to be tested is immersed in an electrolyte to form an electrode. An inert counter electrode and a reference electrode are also placed in the electrolyte. A current is passed from the inert counter electrode to the tested component, and the potential between the component and the reference electrode is recorded as a function of time. In a plot of the electrode potential versus the total charge passed, a series of inflection points identify and quantify particular metallic oxides present on the solder. The plot is compared with previous analyses of aged specimens having known oxide compositions that correlate with degradation of solderability.

Abstract: Etch features are included on a printed circuit (PC) board to be used in monitoring and controlling assembly processes such as soldering. A vernier pattern of etch blocks receives corresponding solder blocks during solder paste screening; misalignment of the solder stencil to the PC board is indicated by an easily-seen interference pattern of spaces created by the superimposed etch and solder blocks. The degree of misalignment can be determined by measuring the distance between the center of the interference pattern and a reference etch block. Also, a scale pattern of etch receives a bar of solder paste; misalignment in the direction orthogonal to the long axis of the scale is indicated by the location of the intersection of the long axis and the solder bar.

Abstract: Assembly of semiconductor chips is accomplished using an acrylate-based adhesive which can be cured rapidly by UV light and which gives an adhesive bond that is resistant to soldering by can be readily removed by solvents after soldering. During assembly, the back sides of the semiconductor chips are bonded to a temporary carrier by the adhesive and adjusted to the proper mirror image position on the carrier before the adhesive is cured. The chip array is then soldered on a component and the temporary carrier is removed from the chips by a solvent.

Abstract: An apparatus and a method for measuring the temperature of a reactive metallic workpiece sealed within a retort prior to and during diffusion bonding of the workpiece. The apparatus includes temperature measuring instruments disposed adjacent preselected portions of the workpiece within the retort, thermal conducting means connecting the instruments with display devices located outside the retort, conduits coupled with the interior of the retort and with the display devices, each of the conduits including a first end portion communicating the interior of the retort with vacuum generating means and a second end portion including at least one tubular region through which the thermal conducting means pass to connect with the display devices, and means for sealing the first and second end portions to maintain an evacuated state within the retort after a vacuum is applied thereto.

Abstract: An improved method for teaching the location of a bond site on a selected lead finger of a semiconductor leadframe during a wire bonding process is provided. Initially, the location of the lateral edges and terminal edge of a tip portion of the lead finger is sensed by an automated vision system of a wire bonding apparatus. A width (W) and a longitudinal axis of the lead finger are then determined. The bond site is located along the longitudinal axis a predetermined distance of (W/2) from the terminal edge of the lead finger. The improved method allows greater accuracy in the placement of bond sites and precisely controls the length of the bond wire used during the wire bonding process.

Abstract: A sequential electrochemical reduction method and apparatus for assessing solderability of electronic component leads and printed wiring boards. The method detects and quantifies the oxides present on copper, solder, and intermetallics that are detrimental to solderability. A solderable portion of the component to be tested is immersed in an electrolyte to form an electrode. An inert counter electrode and a reference electrode are also placed in the electrolyte. A current is passed from the inert counter electrode to the tested component, and the potential between the component and the reference electrode is recorded as a function of time. In a plot of the electrode potential versus the total charge passed, a series of inflection points identify and quantify particular metallic oxides present on the solder. The plot is compared with previous analyses of aged specimens having known oxide compositions that correlate with degradation of solderability.

Abstract: A method is provided for non-contact and contact sensing of phase changes of a solder material. By adding solder to a preexisting solder joint or substrate, an infrared sensor with limited resolution capability is able to discriminate between various solder characteristics at the solder enhanced site and other thermally distracting components when the solder transitions from a solid to a liquid phase or from a liquid to a solid phase. One type of contact sensing of solder reflow is accomplished by holding a thermocouple against a solder joint. When the pre-existing solder volume is insufficient to produce the desired results, additional solder is added to the solder joint or lead. The additional solder may be solid solder, a solder pre-form, or solder paste. Contact sensing may also be achieved by placing a spring loaded probe against the solder and detecting the probe's movement as the solder softens.

Abstract: The accuracy of detection of the quantity of a rosin flux residue (18) left on an electronic assembly (11) after a cleaning operation is improved by using gel permeation chromatography for such detection.