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VDI

Your Source for Terahertz and mm-Wave Products

 

VDI Notes on Diode Specifications

The VDI G and W Band Diode Products are abrupt junction diodes.  Typical forward current vs. voltage (IV) curves are shown on each specification for the customer's convenience.  The following are explanations of the parameters listed on the diode specifications with the exception of the W Band ZBD which has explanations listed on its specification:

  • Vf Forward Turn-on Voltage = Voltage measured at 1 µA forward current
  • ΔV = Voltage measured at 100 µA forward current minus Voltage measured at 10 µA forward current
  • Rs Series Resistance = ((Voltage measured at 10 mA - Voltage measured at 1 mA) - ΔV)/(10 mA - 1 mA) - Probe Resistance
  • Vr Reverse Breakdown = Voltage measured at 10 µA reverse current
  • Ct Total Capacitance = Total capacitance measured pad to pad
  • Cpp Pad to Pad Capacitance = Total capacitance measured pad to pad where the wiring/finger has been removed
  • Cfp Finger to Pad Capacitance = Capacitance measured finger to pad; estimated at approximately 1fF
  • Cj0 (the junction capacitance at zero volts) can be estimated as (Ct -Cpp)/N -Cfp where N is the number of anodes between the pads.

Agilent ADS, AWR Corp. MWO (Microwave Office), and Agilent Genesys models for the W Band Single Anode and W Band ZBD diodes can be accessed at the Modelithics, Inc. website.

Contact [email protected] with any additional questions.

Careers at Virginia Diodes

VDI offers a comprehensive benefits package to full-time employees, flexible hours and a friendly and professional work environment. Our facilities are located downtown in the historic city of CharlottesvilleVirginia close to the University of Virginia and PVCC. We are a growing small business of about 65 employees and enjoy 30% international business. VDI is an equal opportunity employer. Please review our web site for additional details.

 

VDI is currently accepting resumes for a Micro Assembly Technician.  Two years Electronics Technician degree or equivalent/similar experience is preferred.  Experience working under a microscope with microelectronics is preferred.  Retirement and health benefits provided. EOE.  Send resume to [email protected].

VDI is currently accepting resumes for a Millimeter Wave Engineer.  BScEE preferred.  Job involves RF Engineering activities related to the production and testing of 100-1000Ghz Transmitters and Receivers.  Recent grads are encouraged to apply.  Retirement and health benefits provided. EOE.  Send resume to [email protected].

VDI is currently accepting resumes for a Electrical Engineer.  BScEE preferred.  Job involves RF Engineering activities related to the production and testing of 100-1000Ghz Transmitters and Receivers.  Recent grads are encouraged to apply.  Retirement and health benefits provided. EOE.  Send resume to [email protected].

 

 

 

 

 

VDI Notes on Diode Mount and Solder

The following notes are some general guidelines and details that may be helpful when flip-chip mounting/soldering VDI diodes to circuits. The procedure noted here is essentially the procedure used by VDI. The VDI diode solder contact pads are Au thin films. Process times and temperatures are variable and depend upon the Customer’s circuits or substrates being used. This outline is simply intended to give some general guidelines for diode flip-chip mounting and soldering.

  • Adhere circuit or substrate (that will receive diode) to a glass slide; all surfaces should be clean and free of debris, contamination, or residue. VDI diodes are typically soldered to Au circuit traces.
  • Prepare flux. Place one drop solder flux onto new cover slide on hotplate at 120° C for 1 to 3.5 minutes until flux thickens, then apply tiny amounts of prepared flux to circuit or substrate pads with clean probe.
  • Use small, Indium based solder spheres having a melting temperature of approximately 160 C or less. Position appropriate small solder sphere to center of circuit pad in flux. To pre-melt solder, heat slide at 150-170° C for 5-20 seconds. Times and temperatures will vary depending on equipment, environment and substrate materials being used.
  • Re-clean solder surface. Rinse in heated DI water 10-60 seconds and shake off excess water, then dry without melting solder by cycling on/off hot plate for several 3-15 second periods. Lightly blow dry with nitrogen.
  • Place diode on top of solder pads and carefully align. Gently lower weighted cover slide over circuit and diode. Carefully place the carrier slide on a hotplate and heat/solder at 150-170° C for 10-40 seconds. Remove weighted cover slide, rinse, and dry as above.
  • Remove circuit or substrate from glass slide.