Insulation Resistance Measurements

What is Insulation Resistance?

Insulation resistance is measured between two conductors. It is the ratio of the voltage to the total leakage current between the conductors. 

Figure 1 demonstrates a typical short circuit on a PCB with a low resistance value.

Figure 2 demonstrates a potential area where insulation resistance may be affected by the environment etc.

Why Insulation Resistance Important in a PCB?

When a voltage is applied to a PCB under a condition of high humidity, a phenomenon called Electro-chemical migration occurs in which metal ions move from one metal electrode to the other, causing precipitation of metal or compounds. Short-circuiting between electrodes can result as the dissolution and precipitation progress.

The Conductive Anodic Filament (CAF) formation is a well-studied phenomenon that is driven by chemical, humidity, voltage, and mechanical means. It is characterized by a sudden loss of insulation resistance that happens internally in the PCB. CAF dendrites can form between adjacent Plated Through Holes (PTH), or between a plated through hole and a line on the PCB. Plating chemistry, material consistency, damage from multiple soldering steps, and excessive voltages (beyond designed voltages) accelerate the onset of CAF. The mechanism of CAF is an electro-chemical transport of ions across an electrical potential between anode and cathode.

 The following have been reported as factors that influence the rate of Electro-chemical migration:

  • Applied voltage.
  • Insulation material type, structure, configuration, etc.
  • Environmental conditions: Temperature, humidity, gas, etc.
  • Other: Chemical residue left after PCB manufacture, impurities on insulation material, etc.

    As PCB mounting densities have increased to meet demand for smaller and lighter electronic devices, there has been a rapid shift toward narrower-pitch electronic parts, finer-patterned PCBs, and integration of PCBs with other parts. The result has been smaller gaps between conductors, shorter insulation distances and higher average electric field strengths, as well as greater effects from local fields. And since the rise of mobile electronic devices has resulted in more diverse operating conditions, evaluating insulation reliability has become crucial.

Why Gardien’s Solution?

Gardien has implemented a simplified, and flexible solution into our G-Series Flying Probe machines and fixture-based machines.  Gardien designed the process for ease of use on our service floors, allowing accuracy and reduced training (virtually push-button technology).

Parameters that can be adjusted to meet the PCB build requirements:

  • Resistance
  • Voltage within fixed tolerance
  • Ramp and Dwell timeΩ

All information from the PCB fabrication drawing is transferred in the Tooling process via UCAMCO software to the job specific files.  The information is than output into the file that used to perform the measurement.



Mr. Syvret joined Gardien Services Canada as Financial Controller in 2001 and assumed the role of Finance Director North America in 2007. Over the past 20 years, Mr. Syvret has held senior finance and accounting roles, including with Canadian Pacific Ltd and Sprint Inc.



Mr. Niraj Patel joined the company on a part time basis in 1993 while attending college full time. He worked in various positions until he graduated from the Centennial College Computer Systems Technology program, whereupon he was hired full time. He progressed through several testing and CAM department positions and was appointed North American CAM Manager in 1998. After 18 years with the company, Mr. Patel was promoted to Senior Vice President of Operations, Gardien Services Canada Inc. in 2011. In January, 2015 Mr. Patel became Vice President NA of the newly combined organizational unit North America which includes the Canada and USA.



Mr. Todd Kolmodin, a native to the Pacific Northwest was born in Seattle Washington. At a young age he moved to the Portland Oregon area. In March of 1986 he graduated from ITT Technical Institute with a degree in Electronics Engineering Technology. Todd began his tenure in the Electrical Test field that same year.  Todd spent eight years working in an independent testing facility in Wilsonville Oregon where he built skills in all aspects of Electrical Test and Quality Assurance. 

Todd then spent a short term with Yamamoto Corporation on their Engineering staff covering PCB drill, finishing and Electrical Test before joining Probe Test Fixtures in 1995. His charge was CAM and Fixuring Manager.  Todd joined the Gardien Group in September 1998 continuing the same roll and taking on the responsibilities of Quality Manager for Oregon operations. In 2008 Mr. Kolmodin was promoted to Vice President Quality USA. In this position Mr. Kolmodin oversees and maintains the Gardien ITAR registration, ISO Multi-Site registration and multiple site Lab Suitability with the Defense Logistics Agency Land and Maritime. Now also maintaining the Gardien QMS system Todd now serves as Vice President Quality North America.

Mr. Kolmodin is also a published columnist and Technical Presenter with multiple appearances at the IPC Apex Expo Conferences in both San Diego and Las Vegas. 



Mr. Valentini was appointed COO in July 2010 after successfully serving as head of North American operations since 2005.

Roland has over ten years’ experience in the PCB industry, including sales, service, and project management at Atotech GmbH, Germany mainly relating to PCB plating equipment.
He has significant sales experience from his tenure at Mack Rides GmbH and headed up worldwide installations for Lurgi Bischoff GmbH.

Mr. Valentini received a Master’s Degree in Mechanical Engineering from the University of Mannheim, Germany.



Prior to Richard joining Gardien in September 2014, he was Chairman/CEO of tool chain vendor Atego Group Systems Limited which was sold to PTC Inc.

Prior to joining Atego, Richard held a number of Executive and Non-Executive roles including Senior Independent Non-Executive Director of Plethora Solutions, an AIM listed Pharmaceutical Company and CEO of AIM listed Cybit Holdings plc. where he grew the company from inception to revenues of over 25 million and took the company through multiple acquisitions before managing a sale of the business to Francisco Partners.

Richard previously held a number of senior roles in the Software industry.



Mr. Meraw was appointed Group Vice President of Quality in Jan 2015 after successfully  serving as Senior Vice President of USA operations since 2011.  Prior to being responsible for USA operations Mr Meraw was responsible for Canadian operations since 2001.

Rick has over twenty years’ experience with Gardien Group and has various roles including, service technician, customer liaison, Quality manager, technical support, project management, and software design/ implementation.

In June 1992 he graduated with an Electronic Engineering Technologist degree, with honors from a local community college.

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