3 Replies Latest reply on Nov 15, 2012 8:22 AM by DenisL

    How to add Microvias

    faizan.ul-haq
    faizan.ul-haq Nov 15, 2012 7:00 AM

      Hi,

       

      I need to add microvias of 50um diameter with drill size of 47um for 0.4mm pitch BGA package routing. So far i am unable to find options in PADS layout to put such small microvias. I tried to define microvias of 50um dimensions using

       

      Setup>Pad stack>Pad stack type>Via

       

      The probelm is that the software does not accept such small via dimensions. When i put via diameter of 2mil and drill size of 1.85mil, software starts complaining that your drill size is more than via size..:/

       

      Can anybody help. Screenshot is attached

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        • 1. Re: How to add Microvias
          DenisL
          DenisL Nov 15, 2012 7:30 AM (in response to faizan.ul-haq)

          In the Tools>Options dialog look at the Design tab and check the drill oversize setting. You may need to 'temper' your drill size based on the oversize setting. I seriously doubt that you need or can achieve a 50u hole diameter ever with a laser uVia. Personally, I'd set the uVia pad diameter to be the same as the solder pad for the BGA and downsize the drill from there. I would advise engaging in a dialog with your fabricator to establish their capabilities and recommendations for your uVia.

          • 2. Re: How to add Microvias
            faizan.ul-haq
            faizan.ul-haq Nov 15, 2012 7:41 AM (in response to DenisL)

            Thanks DanisL, I took the dimensions of microvia pad from the attached document (page 36).Can you check that. If I set the uVia pad diameter to be same as the solder pad for BGA then what should be the size of drill i need to use in this configuration?

             

            BR

            • 3. Re: How to add Microvias
              DenisL
              DenisL Nov 15, 2012 8:22 AM (in response to faizan.ul-haq)

              From your document, on page 36 I see a guide of 225um[9mil] pad and 125um[5mil] laser drill.

              The 47-50um numbers are the SM oversize to create a SM dam between land areas.