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  1. #1
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    Default Help! - with tiny SMD parts

    Well my boards are back (rev2). I had to add resistor networks in the output lines to attenuate ringing.

    Since this is only a purpose-built board (not generic or intended to be used across a wide range of uses) I decided to directly solder resistor networks rather than use pluggable (SIP) style. I went with 0603 (x4) size to avoid increasing my overall board size. Remarkably, I've recently started using 0603 (single-element - e.g. MLCC, LED, TF resistor) parts and not had a problem with assembly.

    I started assembly last night. After soldering these parts, the other SOIC and single-element 0603 seem trivially easy.

    It's really, really hard to hand solder the 0603(x4) networks without bridging across the terminals. Even using my smallest tip (1/32" conical Weller) and tons of flux (from a pen) and thin solder. I damaged one pad but was able to fix it. I've checked for continuity/shorts and all looks good at this point, but I have concerns about reliability in service (temperature cycles, moisture).

    Are there any recommendations on alternatives to hand-soldering (or how to hand-solder more "cleanly")? I'm wondering if I could use solder paste and a hot air station for these parts (only). I've seen cheap air stations on Amazon for about $40, but they also have reviewers claiming they catch on fire or melt in the first few uses. I don't have an old toaster oven (or time to convert to a reflow oven) but could also consider purchasing a cheap one that worked for low-volume (and didn't catch on fire).

    If I try to use solder paste, will I just end up bridging the pads anyway? the pads are 0.45mm (18mil) wide on a 0.8mm (31mil) pitch. Is there a "special trick" for applying solder paste like this, and what type of applicator/dispenser is used? I don't want to spend big $$ on this as it's not something that I will often be doing.
    Last edited by ags0000; 05-03-2018 at 01:07 PM.

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