Electronic Components Solutions

Is reliability and enhanced terminal strength essential in your power application

Is reliability and enhanced terminal strength essential in your power application

KOA's WK73-series has a 90° rotated design and offers several advantages compared to standard resistor footprints. A three times higher power rating in case of 0612 vs 1206 size is the most visible. This can save board space and is based on the improved heat dissipation through the solder joints. Much higher terminal strength is related to the bigger soldering area. The lower distance between the terminals, results in less expansion stress to the solder joints. The inner resistive pattern causes less temperature rise. All the above mentioned benefits combined, result in a superior reliability compared to standard flat chip resistors. The lower distance between the terminals, results in less expansion stress to the solder joints. The inner resistive pattern causes less temperature rise. All the above mentioned benefits combined, result in a superior reliability compared to standard flat chip resistors.

    Rated Power

  • Rated Power of a resistor strongly depends on the maximum available heat transport capability, which mainly relies on heat conduction through the solder joint to the PCB. The temperature dissipation through air convection and radiation can be neglected. Knowing this, KOA offers the WK73 flat chip resistor with inverse geometry. Instead of using the short sides for the electrodes (like at standard flat chips) the long sides of the resistors are used for better heat dissipation through the solder junctions.

  • Size 1206:

  • power rating 0.25W, longer distance between the terminations, absolute stress at solder fillet is higher, higher thermal expansion.

  • Size 0612:

  • Power rating 0.75W, short distance between the terminations, small mechanical stress at solder fillet, low thermal expansion.

  • Main Advantages

    • Improved solder joint reliability
  • • Excellent heat dissipation characteristics
  • • Superior temperature and power cycling performance
  • • Low thermal expansion stress
  • • Higher rated power - less board space than standard