Connector Pins Research Articles

Chemical characterization of failures and process materials for microelectronics assembly

PurposeThe purpose of this paper is to discuss the chemical characterization of failures and process materials for microelectronics assembly.Design/methodology/approachThe analytical techniques used for chemical structures and compositions including Fourier transform infrared spectrometer (FTIR), scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy are conducted.FindingsThe residues on the golden finger are identified to be the flux used in the assembly processes. Besides, the contaminants on the processed and incoming connector pins are verified to be polyamides (–CONH functional groups) from housing material's residue. Three liquid fluxes used in wave soldering are analyzed by their chemical structure. One flux showing the OH groups at 3430 cm−1 indicates higher acid contents. This consists with the acidic values specified by the supplier. Also, the solder mask under study has ever appeared peeled‐off issue. The FTIR spectra results indicated 62.2 percent degree of curing while vendor's spec is above 70 percent.Originality/valueThe establishment of the Infrared spectra database for fluxes and process materials help determine the root cause of the contaminants to reduce re‐occurrence of similar problems and thus enhance the manufacturing capability. The infrared spectrophotometry technique can be used by professional original design manufacturing and/or electronics manufacturing service, providers to investigate board/component defects during product pilot run stage and volume production.

Reduction of Transient Far-End Crosstalk Voltage and Jitter in DIMM Connectors for DRAM Interface

The transient far-end crosstalk voltage and the crosstalk-induced jitter of dual in-line memory module (DIMM) connectors are reduced by about 80% by increasing the mutual capacitance between DIMM connector pins with the additional interdigitated-comb-shaped metal-stub patterns on the motherboard. It was confirmed by the far-end crosstalk voltage waveform measurements using TDR and the eye diagram measurements at the data rates of 15 Mbps, 100 Mbps, and 3 Gbps. This reduction technique can be applied to the connectors where the inductive coupling ratio is larger than the capacitive coupling ratio.

Material morphology and electrical resistivity differences in EPDM rubbers

AbstractElectrical resistance anomalies noted in EPDM gaskets have been attributed to zinc‐enriched surface sublayers, about 10‐μm thick, in the sulfur cured rubber material. Gasket over‐compression provided the necessary connector pin contact and was also found to cause surprising morphological changes on the gasket surfaces. These included distributions of zinc oxide whiskers in high pressure gasket areas and cone‐shaped features rich in zinc, oxygen, and sulfur primarily in low pressure protruding gasket areas. Such whiskers and cones were only found on the pin side of the gaskets in contact with a molded plastic surface and not on the back side in contact with an aluminum surface. The mechanisms by which such features are formed have not yet been defined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Accelerated aging and thermal-mechanical fatigue modelling of Cu-plated through holes with partial solder filling

The reliability of connector-to-board solder joints was investigated by accelerated aging experiments and finite element analysis (FEA), with a strain-based criterion for fatigue failure of Cu vias. The accelerated aging temperature cycle was ?55?C to +125?C. The pin/through hole solder joints were examined by metallography after test intervals up to 1000 thermal cycles. Partial solder filling of the joints was observed and attributed to Au contamination of the solder and thin solder gaps between the connector pins and Cu-plated vias. All fatigue cracks observed in the vias after thermal cycling were associated with partial solder filling of the joints. The effects of partial solder fill on failure location were confirmed by FEA and acceptable agreement was found between the predicted cycles to failure and the experimentally observed onset of via cracking. The model and experimental results were used to predict component lifetimes for milder thermal-cycle conditions typically found in service.

The Development and Testing of a Multi-Depth Microwire Electrode Array

We describe a method by which a single shaft multi-microwire electrode can be easily and efficiently fabricated. The constructed electrode can then be used for multi-depth neuronal unit recording from one or more tracks in deep brain structures of anesthetized or awake animals. The electrode consists of multiple strands of 50 μm Teflon insulated tungsten microwires threaded through a 25 gauge stainless steel cannula. The individual microwires are then cut to specified offsets, depending on which layers the researcher is interested in. In this case the three wires present are cut to 1 mm, 600 μm, and 250 μm from the tip of the distal end of the cannula. These distances correspond to the II, III, and V layer of the rat sensorimotor cortex. At the base of the electrode, the wires are soldered to individual pins of a miniature connector that plugs into preamplifier that is part of a TDT (Tucker-Davis Technologies) modular signal processing system. Although in vivo data has yet to be attained and analyzed for this type of an electrode, EIS (Electrochemical Impedance Spectroscopy) analysis has shown that the electrode design is well suited for brain tissue recordings.

Preservation of a subcutaneous pocket for vagus nerve stimulation pulse generator during magnetoencephalography

Patients with epilepsy and an implanted vagus nerve stimulation (VNS) device who are referred for consideration of definitive epilepsy surgery (removal of the epileptogenic cortex) may require magnetoencephalography (MEG), a study requiring explantation of the pulse generator, as part of their evaluation. Nonetheless, these patients may not wish to abandon palliative VNS therapy should definitive surgery prove unsuccessful or impossible. To avoid obliteration of the pocket by scar tissue after the pulse generator is explanted, the authors have preserved the dead space in several patients with insertion of a similarly sized silicone block. This block is easily replaced with the pulse generator if continued VNS therapy is appropriate, and is left in place in patients who appear to no longer require VNS therapy. Upon completion of MEG, if pulse generator replacement proves desirable, atraumatic retrieval of the electrode connector pin and body is easy. Silicone block implantation during what may prove to be temporary device explantation facilitates reuse of the original pulse generator implantation site and atraumatic distal electrode wire retrieval.

Tester Board for testing mass-produced SMB modules for CMS Preshower

We have developed a Tester Board to test the electrical characteristics of theSystem Motherboard (SMB) for the CMS Preshower detector at CERN. The board is designedto test input resistances, output resistances, connections, interconnections and possible short-circuits of a module having up to 640 connector pins. The Tester Board is general-purpose innature: it could be used to test any electronic module or cable by using dedicated cable sets. Themodule can detect a variety of problems not detected by either functional tests or the "flyingprobes" technique. The design, algorithms and results of using the Tester Board during massproduction of CMS Preshower SMBs are presented.

Inspection processes must compliment systems inspected

If the goal is to improve either aviation or shuttle safety and systems reliability, then modern methods of wire systems diagnostics, prognostics, mediation, repair, and validation are a must. This requires using modern non-destructive evaluation (NDE) procedures and equipment which yields information that supports the operator's wire health management program and feeds into his aging aircraft or shuttle containment processes. Commonly used wire inspection processes do not compliment aircraft electrical systems making it difficult to diagnose wiring problems or manage wiring systems health. The wire inspection tools in common use today can be represented by the volt/ohm meter, the meg/ohm meter, and visual techniques. The two meters only measure conductivity, connectivity, and insulation breakdown strength. Visual techniques, mirror and flashlight methods only reach about 25% of the aircraft wiring and subjectively identify only physical faults of the insulation and simple damaged components. Little can be determined relative to the wire, insulation, bundle, connector, connector pins, backshell, wire supports, grounding, shielding, or intended electrical systems performance. All items where data is necessary to analyze and manage the health of the system. Guidance material is currently not available for the electrical repairman for even a simplified zonal inspection. The user community also reports gross shortcomings in the guidance supplied by the manufacture's maintenance and repair manuals.

Modelling the effect of port recession on VNA one-port calibrations

In the past, considerable attention has been devoted to the effect of recessed connections on the accuracy of vector network analyser (VNA) calibrations. Recession, defined as the gap between connectors, produces a discontinuity in the transmission line, which can be modelled as a short section of line with a different characteristic impedance. The parameters which define this discontinuity are the diameter and length of the intermediate section. The diameter is that of the male connector pin and the length is a function of the recession and/or protrusion of both connectors. Together with the diameter of the outer conductor, these parameters allow the calculation of the characteristic impedance of the section and the reflection coefficient of the termination. Simulations of the performance of a mismatch airline are presented in order to assess the correctness of our model. Subsequently, the same model is applied to the open-short-sliding load calibration of a vector network analyser. We show that the effects of recession during calibration and/or measurement can be predicted with the aid of computer simulations. Finally, the theoretical predictions are compared with results obtained experimentally.

The pin pixel detector—X-ray imaging

The development and testing of a soft X-ray gas pixel detector, which uses connector pins for the anodes is reported. Based on a commercial 100 pin connector block, a prototype detector of aperture 25.4 mm×25.4 mm can be economically fabricated. The individual pin anodes all show the expected characteristics of small gas detectors capable of counting rates reaching 1 MHz per pin. A 2-dimensional resistive divide readout system has been developed to permit the imaging properties of the detector to be explored in advance of true pixel readout electronics.

The pin pixel detector—neutron imaging

The development and testing of a neutron gas pixel detector intended for application in neutron diffraction studies is reported. Using standard electrical connector pins as point anodes, the detector is based on a commercial 100 pin connector block. A prototype detector of aperture 25.4 mm×25.4 mm has been fabricated, giving a pixel size of 2.54 mm which matches well to the spatial resolution typically required in a neutron diffractometer. A 2-Dimensional resistive divide readout system has been adapted to permit the imaging properties of the detector to be explored in advance of true pixel readout electronics. The timing properties of the device match well to the requirements of the ISIS-pulsed neutron source.

Automatic Pace-Sense Polarity Switch as an Indicator of Early Lead Corrosion: The Usefulness of Impedance Trend Graphing

A rate responsive dual chamber pacemaker system (Medtronic Inc.) was implanted without complications. At 6-week postimplantation a routine pacemaker check showed a spontaneous switch from programmed bipolar pace-sense to unipolar pace-sense on the atrial and ventricular leads. Pacing and sensing thresholds were not significantly changed from implantation. The atrial and ventricular lead impedances increased from 680 and 720 ohms at implantation to 1,290 and 2,400 ohms, respectively. The device was reprogrammed to bipolar pace-sense and the continuous lead telemetry trend option was programmed On. Evaluation of the system 1 month later revealed a decrease in atrial and ventricular lead impedances, 680 and 2,100 ohms, without a change in pace-sense polarity. One month later, the lead polarity had again switched from programmed bipolar to unipolar pace-sense. The lead trend data revealed stable atrial impedances with sporadic increases in the ventricular lead impedance to values > 3,000 ohms. The pacemaker lead system was invasively investigated and visible gross corrosion of the ventricular lead distal connector pin was discovered.

Parameter extraction and electrical characterization of high density connector using time domain measurements

Two coupled connector pins can be represented by an equivalent circuit consisting of six parameters, namely, self capacitance/self inductance per pin, mutual capacitance between pins and mutual inductance between pins. A systematic parameter extraction algorithm has been discussed in this paper using time domain reflectometry (TDR) measurements. This method uses a combination of stand-alone, common mode, and differential mode measurements to extract the connector parasitics. The accuracy of the equivalent circuit has been studied in detail using crosstalk measurements.

Reducing Cannon Plug Connector Pin Selection Time and Errors Through Enhanced Data Presentation Methods

This research investigated the effects of data presentation formats on technician performance when maintenance procedures are presented on a monocular, head-mounted display (HMD). The maintenance task was a continuity check performed by identifying, selecting, and testing pairs of cannon plug connector pins. Two formats were used to present task procedure information to the subject: a format that mimicked the standard technical procedure manual, including the textual and graphical characteristics; a format which provided the same information as the first, while adding visual cues to the graphical portion of the technical information. Two types of cannon plugs were used: ‘few-pin’ plugs (12 and 13 pins) and ‘many-pin’ plugs (55 and 79 pins). United States Air Force (USAF) avionics maintenance technicians stationed atBarksdale Air Force Base, Louisiana served as subjects. Dependent measures were: task completion time, task error rate, and subjective reports on the usability of the information presentation structure and the HMD. Results indicate that in general, technicians perform tasks more quickly and commit fewer errors when using enhanced graphical data presentation methods. Technicians indicated via post test questionnaire that such data formats, and HMDs in general, could be a useful tool in the performance of their maintenance duties.

Measurement and simulation of crosstalk reduction by discrete discontinuities along coupled PCB traces

Crosstalk among interconnects and printed-circuit board (PCB) traces is a major limiting factor of signal quality in high-speed digital and communication equipment. The paper evaluates coupled surface microstrip transmission lines with periodical loading and coupling. The situation may represent stray coupling and loading of digital buses due to connector pins, plated through holes at connector slots, and stubs as well as the input capacitance of active devices. This paper shows that discrete periodical coupling along coupled surface microstrip transmission lines may be used to reduce far-end crosstalk. An expression is given to calculate the discrete coupling capacitance to achieve optimum far-end crosstalk reduction. The reduction of far-end crosstalk is verified by measurements, and the good agreement between the simulated and measured data is shown. On the other hand, discrete loading does not significantly reduce near-end crosstalk, but will introduce additional ringing in the time domain. >

Two-dimensional array transducers using thick film connection technology

A connection technique for two-dimensional array ultrasound transducers developed by combining a conductive lambda/4 mismatching layer with a multi-layer ceramic (MLC) connector using thick-film microelectronic technology is described. The connector consists of 20 thick films of alumina and screen printed metallization with customized interconnections between the layers called vias. Ten ground layers are interleaved between ten signal layers to reduce elecrical crosstalk. A lambda/4 mismatching layer of conductive epoxy is bonded between each PZT element and the silver metal pad of the MLC connector to provide an effective low impedance backing. In the current configuration, a 16x16 transducer array, 0.6 mm element spacing, is expanded to a 16x16 grid of connector pins at a standard spacing of 2.5 mm. Vector impedance, sensitivity, bandwidth, interelement uniformity, and crosstalk are all in good agreement with arrays of conventional fabrication. However, an array with MLC connector can be fabricated more quickly independent of the number of elements.

Analysis of set screw and side-lock connector reliability.

A retrospective review of complications with connectors and lead-to-header interfaces was performed following 649 pacing procedures between 1980 and 1990. There were 88 lead revisions (13.6%), 81 device replacements or modifications (12.5%), and 480 new implants (74%) using devices of five manufacturers. Two basic connector types were studied, one utilizing a set screw and the other using a side-lock compression fitting. The set screw makes electrical contact and mechanically secures the lead connector pin with a set screw insulated by a self-sealing grommet or an integral or separate set screw cover. The side-lock makes electrical contact with an automatic spring mechanism while the plastic lead terminal is secured in the connector block of the pacemaker by a Delrin side-lock compression fitting. Four hundred fifty-nine set screw connector devices were followed for up to 12 years with 14 complications (3.1%) whereas 82 side-lock connector devices were followed for up to 5 years with one complication (1.2%). The set screw and side-lock connectors were reliable over the period of follow-up. Although the complication rate appeared lower with the side-lock, follow-up was shorter and the number of implants smaller. With the leads used in this study, the side-lock proved to be a desirable feature due to simplicity, speed, safety, and ease of use. One limitation is the requirement for a precise IS-1 connector terminal diameter.

A multiwire microelectrode for single unit recording in deep brain structures

A method is described by which a single shaft multiwire microelectrode can be fabricated efficiently. The resulting electrode can be attached to a commercial microdrive and used for single neuronal unit recording from one or more tracks in deep brain structures of anesthetized or awake animals. The electrode consists of a 30 gauge stainless steel cannula through which multiple strands of 13 μm insulated tungsten microwires are threaded. At the electrode tip the wires protude 3–4 mm from the cannula and are cut individually at suitable offsets. The tip is stabilized and fixed to the cannula with cyanoacrylate. At the base of the electrode the wires are threaded through flexible plastic tubing that provides strain relief and are glued to individual pins of a miniature connector that plugs into a field effect transistor (FET) voltage follower. Good single unit recordings have been obtained routinely from the basal ganglia of awake, behaving monkeys with this electrode.

Interperiod capacitance calculations for three-dimensional multiconductor systems

An approach is proposed to facilitate the capacitance calculations for periodic three-dimensional multiconductor systems. Based on the Fourier transform technique, the approach requires only the conductors inside one period and solves the charge distribution in the spectral domain by the integral equation method. The resultant spectral capacitances are then inverse transformed to give the capacitances between any two conductors, which may even be inside different periods. The approach is applied to the capacitance analysis for connector pins in a packaging board design. >

Electrical Parameter Analysis from Three-Dimensional Interconnection Geometry

TRISIM1, a capacitance and inductance calculation program for complex three-dimensional geometries, is described. The basic algorithm of capacitance calculation is Green's function integral equation method and the inductances are calculated by Neumann's formula applied to the thin filaments which make up the conductor segment. In TRISIM1, for efficient use of these algorithms, 1) triangular capacitance cells are adopted, 2) the calculation of the matrix element G <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ij</inf> is simplified according to the cell distance, and 3) the filaments for inductance calculation are infinitely thin. An approximate method of filament selfinductance calculation is used and the proof of its validity is given. The convergence of the numerical results to analytical or two-dimensional solutions is illustrated for simple geometries. The crosstalk noise induced among connector pins is calculated and the results are in good agreement with the measured data.