• Solder

    05/31/2019 at 12:39 0 comments

    Luke says:

    May 30, 2019 at 10:16 am

    The bismuth based solders would be nice, but they tend to be rare as hens’ teeth and expensive when you do find them from a local supplier. Also, the low melting point of 139 C is a little bit too close for comfort for some components like high power high temperature FETs that may run up to 150-200 C.

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    Luke says:

    May 30, 2019 at 10:24 am

    Apparently, if there’s any lead involved, such as with pre-tinned wires or leads, the combination of Bi58Sn42 and the lead can lower the melting point to 95 C and create very weak and brittle joints that can be pried apart with a toothpick.

    And in general bismuth solders have inferior mechanical properties, being somewhat brittle and stiff even when there’s no lead involved.

    AMS says:
    May 30, 2019 at 8:10 pm

    Having tried quite a few, SN100C (It’s .7%cu, .05%Ni, .009%Ge Balance Sn) is about the best you’ll get other than 37/63 SnPb stuff. Yeah it’s higher temp but it wets well, is eutectic, and shiny, and doesn’t get all dross filled when soldering big stuff like 97/3 SnCu or SAC305.

    All from



  • Seeed PCB arrived!

    11/20/2018 at 02:40 0 comments

    Recently I got the opportunity to order PCBs from Seeed Studio through their Fusion PCB service. As you can see from the pictures it is a more artistic than complicated PCB and the quality is outstanding. I designed the board with relaxed spec of 7/7mil trace width/spacing and 0.3mm hole size, which fit perfectly in the most price competitive option. Registration of all layers, including soldermask and silkscreen is excellent, everything is centered and no unwanted overlapping onto the pads. Also the PCB outline is routed all the way around and the break-off tabs are not noticeable at all. 

    Also the silkscreen resolution really good, virtually no steps are visible on angled or curved lines, which makes it very usable for advanced graphics.

    Pricing is competitive when using the HASL option and the standard 2-layer 100mm x 100mm size restriction. I went for HASL lead free, as the boards are intended to be sold in my Tindie store once all parts arrive. The circuit is operational with a mock-up LED and the FR4 substrate acts as a nice diffusion layer for the light.

    I opted for shipping through DHL which took 4 days from China to Canada to the local depot, and another 4 days for the local contractor to deliver because they ignored my instruction for pickup at the depot. This is not controllable by anybody at the shipping or receiving end, so it was just bad luck for me. Other shipping options are available.

  • Reads

    01/22/2017 at 04:12 0 comments