A Study on Measuring Contact Resistance of Ball Bonds on Thin Metallization

Abstract

Contact resistance measurement configurations for the evaluation of ball bond reliability on thin metallizations are studied. Samples with symmetrical and asymmetrical four-wire probe configurations are analyzed and compared with a calibrated finite-element model. It is found that the measured contact resistance strongly depends on the geometric placement of the probe wires, and the value closest to the true value is obtained from a probe placement that is opposite and away from high-current-density regions on the metallization. Probes should also be placed as close as possible to the contact interface. Sheet resistance components contributed by intermediate thin metallizations are of the same order of magnitude as the unaged reported R C . Therefore, they are considered. Symmetrical current distributions yield a more homogeneous potential drop across the bond interface being probed, but also capture a larger component of metallization sheet resistance. Experimental samples were aged, and the contact resistance increase was measured. The impacts of various probe placements on the sensed R C were studied.

Low-Cost Online Contact Resistance Measurement of Power Connectors to Ease Predictive Maintenance

“…The initial resistance is initially measured by means of the resistance is commonly done by applying the standard Kelvin or 4-wire method as schematized in Fig. 1, since the results are not influenced by the resistance of the probes [27]. This measurement requires a 4-leads micro-ohmmeter, which injects a stabilized DC current I DC and measures the voltage drop V DC across the connector.…”

Monitoring of thermo-mechanical stress via CMOS sensor array: Effects of warpage and tilt in flip chip thermo-compression bonding

“…Therefore, the cycling of all 64 pads takes 64 ms. Each of these bond pads is surrounded by a local RTD sensor ( Fig. 2a, b, c) consisting of a serpentine structure of top metal Al to be used in conjunction with similar fourwire or Kelvin measurement techniques as discussed in [9][10][11][12] with lead resistance elements that include CMOS switching. The RTD gives the average temperature in the area covered by the serpentine lines around the bond pad.…”

“…Tools for measuring temperature and stress in-situ during wire bonding were demonstrated in [9][10][11][12][13][14][15][16]. These tools were developed and were comprised of piezoresistive and RTD elements to integrate force and temperature sensors via CMOS processes.…”

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“…A number of methods have been employed to calculate the contact resistance in the literature including finite element analysis (FEA), experimental measurement, and electrical contacts model analysis (ECMA) [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. In the FEA method, some researchers have added an extremely thin film on the contact interface of the two connectors.…”

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