2 Replies Latest reply on Mar 19, 2019 4:19 PM by carys_86

    Solder Joint Life


      AN72845 Design Guidelines For Cypress Quad Flat No-Lead (QFN) Packaged Devices makes the following statement on page 16:


      Typically, QFN-packaged devices are highly reliable when assembled on rigid PCBs when the bottom thermal pad of the QFN package is soldered to the board. When the thermal pad is soldered onto the PCB, the life of the solder joint is extended by 60 percent. For this reason, soldering the thermal pad onto the board is crucial to the reliability of the solder joints on PCBs.


      Is there data available to show the 60% solder joint life improvement?  If so can you share it?  I need to show the reliability of the PSoC5 chip I am using and it would be really helpful.




        • 1. Re: Solder Joint Life

          Cypress?  Are you going to reply?

          • 2. Re: Solder Joint Life

            Hello Cyrus,

            The 60% in the application note came from our assembly subcontractor. However, since then we did our own evaluation which confirmed the assembly subcontract's statements.


            Below is a summary of the BLR evaluation we performed in August 2016 using a DFN package.


            8LD DFN BLR Test Summary
            BLR No.BM-1602-TC-005BM-1602-TC-007
            Package8LD DFN8LD DFN
            Lead Frame P/N4107541075
            EPAD Soldered to PWBYesNo
            Number of Units submitted to Stress3232
            First Failure N/A854 Cycles
            Number of Units Failed023
            Number of cycles completed2,0001,250 (Stopped)



            Cary Stubbles

            Cypress Semiconductor

            Sr Staff Packaging Engr