Study of Probe Pin Internal Resistance

Prepared by Takuto Yoshida
Presented at BiTS China Workshop, Suzhou on September 13, 2016


CRES Comparison by Pin Design

Pin Pitch: 0.8mm

Test Height: 2.5mm

Pin Design:

“A”: 10gf, 4‐point crimped PA

“B”: 25gf, 4‐point crimped PA

“C”: 42gf, 4‐point crimped PA

“D”: 28gf, Combined PA and Barrel

  • Higher pin force is lower CRES pin
  • Combined PA and Barrel pin (“D”) is the lowest CRES pin
  • CRES differ by pin design (18 mOhm to 33 mOhm)

CRES Composition in a Probe Pin


PA: Plunger A (device side)
PB: Plunger B (PCB side)
BR: Barrel

Spring is removed from the drawing because it is no contribution to CRES path

Material Resistance

(1) PA material electrical resistance

(2) BR material electrical resistance

(3) PB material electrical resistance

Contact Resistance

(4) PA pad to PA contact resistance

(5) PA to BR contact resistance

(6) BR to PB contact resistance

(7) PB to PB pad contact resistance

Material Resistance

R: Electrical resistance (measured in ohms, Ω)

ρ: Electrical resistivity (measured in ohm⋅meters, Ω⋅m)

L: Length of material (measured in meters, m)

A: Cross-sectional area of material (measured in square meters, m2)

Total Material Resistance
R = 0.003 Ohm

  • Material resistance contribution is only 9% to 17%
  • Contact resistance is main player for pin CRES

Contact Resistance

  • R: Electrical resistance (measured in ohms, Ω)
  • Rc: Constriction resistance (measured in ohms, Ω)
  • Rf: Film resistance (measured in ohms, Ω)
  • Ro: Metal specific resistance (measured in ohms, Ω)
  • ρ: Electrical resistivity (measured in ohm⋅meters, Ω⋅m)
  • a: True contact area diameter (measured in meters, m)
  • σ: Film electrical resistivity (measured in ohm⋅meters, Ω⋅m)
  • d: Film thickness (measured in meters, m)
  • Constriction resistance contributor
    • Contact area shape
    • Contact force
    • Plating material and thickness
    • Hardness
    • Surface roughness
  • Film resistance contributor
    • Material
    • Thickness

Individual CRES Measurement

Source Meter Keithley 2400

  • Digital Multimeter Yokogawa 7555
  • PA Pad and PB Pad compress DUT
  • 3 small probes to contact DUT surface
  • R(PA Pad‐PA) = V1/0.1
  • R(PA‐BR) = V2/0.1
  • R(BR‐PB) = V3/0.1
  • R(PB‐PB Pad) = V4/0.1
  • Measure 10 times for each session with current of +0.1A and ‐0.1A by considering thermoelectric effect
  • Measured voltage was different by thermoelectric effect
  • Average voltage value for resistance calculation
New Pin Individual CRES

  • Pin Design “A” (10gf), “B” (25gf), “C” (42gf), “D” Combined PA and BR
  • Spring force is most to contact resistance of PA pad – PA, secondary for PB – PB pad
  • Combined PA and BR design for “D” design improve contact resistance of PA – BR
After 300K Cycle Individual CRES

  • Pin Design “A” (10gf), “B” (25gf), “C” (42gf), “D” (28gf) Combined PA and Barrel
  • Cycle effect mainly impact to contact resistance of BR – PB
  • Secondary impact to contact resistance of PB – PB pad


Pin Design “A” New vs. 300K

  • 300K cycle test effect mainly impact to contact resistance of BR – PB
  • Secondary impact to contact resistance of PA pad – PA
Pin Design “C” New vs. 300K

  • 300K cycle test effect mainly impact to contact resistance of PB – PB pad
  • Secondary impact to contact resistance of PA – BR
Pin Design “B” New vs. 300K vs. 3.5A 110hours

  • Current effect mainly impact to contact resistance of PB – PB pad
  • Secondary impact to contact resistance of BR – PB
  • Current effect is smaller than Pin Design “B”
  • Low temperature rise by current seems good for pin stability (Low CRES provide low heat (temperature rise))


  • Understand CRES Composition in a Probe Pin
  • Probe Pin CRES main player is contact resistance
  • We can measure each contact resistance by using 4‐wire measurement method
  • Higher pin force effective to reduce contact resistance of PA pad – PA
  • 300K cycle test impact to contact resistance of BR – PB (BR internal surface roughness and PB base shape seems big change)
  • 3.5A 110hours test impact to contact resistance of PB – PB pad
  • We feedback the probe pin design by result of individual CRES data

2016 Highlights

  • Consolidation of CNC production to one site for better production efficiency and cost effectiveness
  • Span off the PCB division to align with our mid to long term objective of focusing on probe pins and test socket business

2015 Highlights

  • TTSG celebrates its 35 years of engineering success in the semiconductor test tooling industry. Our growth and progression have been made possible with the help and support of our stakeholders including our customers, employees, shareholders, community, and others. We would like to express our heartfelt gratitude to these individuals and institutions that have collaborated with us over the last 35 years.

    To mark this significant milestone, TTSG has launched a “Celebrating 35 Years” logo, which will appear on all TTSG’s marketing collateral.

2014 Highlights

  • Test Tooling Solutions Group announced the merger and integration of Kenshi Singapore and rebrand the new entity under the Test Tooling Solutions Group, effective 1st Sept 2014.
    The merger is expected to further strengthen the core competency and technical capability of the combined unit in the provision of test and tooling solutions and to better position the Group to capture any new business opportunity, in a fast changing landscape.
    The integration exercise is expected to be completed before end of the year.
  • In line with its expansion plan, TTS Taiwan has moved to a bigger facility in Hsinchu. The new office, housing the sales, application and design centre, is within a 5 mins walking distance from the Hsinchu HSR Station. In conjunction with the Semicon Show Taiwan, the new office was officially declared open by the Group CEO and we are glad to receive our first visitor from Toshiba Japan. Our office is located at 8F-3, No.229, Fuxing 2nd Rd., Zhubei City, Hsinchu (新竹縣竹北市復興二路229號8樓之3)
  • TTSG today announces the successful registration of the company logo and tagline. The trade mark is granted under the registration number 2012018638 for a period of 10 years.

2013 Highlights

  • TTSG has been granted the patent for its new probe pin design in Japan. This new probe pin design has a longer spring coil that tapered gradually to reduce stress and improve the electrical performance as well as life span of the pin.

2012 Highlights

  • TTSG is pleased to introduce the new green logo and tagline- feel green, live green and be green ©
  • Received an award from Broadcom Inc in recognition of our outstanding service and support
  • TTSG has acquired another 10 units of brand new CNC machines from Citizen and Fanuc with a list price of more than USD1 million as part of the expansion plan
  • TTSG has been granted the patent for Offset Taper Spring (OTS) by the United States Patent and Trademark Office (USPTO) filed on Dec 27, 2011

2011 Highlights

  • Setup secondary processing plant in JB
  • Expansion of TTS Thailand to double the capacity
  • Launch of New Corporate Branding
  • Arrival of 10 more new Citizen machines, latest model auto lathe machines from Japan as part of the overall expansion plan for 2011
  • Integration of Kenstronics Malaysia with Test Tooling Solutions Group

2010 Highlights

  • Expansion of TTS Japan to a new office at Kawasaki, Kanagawa, Japan

2009 Highlights

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  • Test Tooling Solutions (TTSM) and Test Tooling Designs (TTDM) have achieved the certification of ISO 9001:2008 for Quality Systems

2008 Highlights

  • Obtained the certification for RoHS (Directive 2002/95/EC on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment) for its Test Probe
  • Acquired 100% of the R-Squared Circuits Inc, a Printed Circuit Board Manufacturer for ATE testers located in Folsom California

2007 Highlights

  • Setup Auto Lathe factory in JB
  • TTSM officially took possession of Plant A in Penang

2006 Highlights

  • Purchased 50,000 sq. ft of a new production facility in Johor, Malaysia
  • Completed the expansion and renovation of Plant B in Penang
  • Acquired BigHub Technology Sdn Bhd and change its name to Test Tooling Designs (M) Sdn Bhd (TTDM)
  • Established its wholly owned subsidiary in Malaysia, Test Tooling Solutions (M) Sdn. Bhd. (TTSM)
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  • Relocation of Corporate HQ from USA to Singapore