Some holes difficult to solder

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Some holes difficult to solder

Postby junktronix » Tue Jun 18, 2013 12:19 pm

When assembling my control board, I noticed that some of the holes are really difficult to solder well. The solder solidifies before flowing well into the hole and requires a *lot* of heat to get a nice, shiny fillet. I'm pretty sure this is due to those holes being connected to the ground plan layer without a thermal relief. I've got a very nice Pace soldering station and 30+ years experience soldering. If it was difficult for me, I'm sure there are going to be a lot of poorly assembled boards out there.

Has anyone else noticed this?
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Re: Some holes difficult to solder

Postby Bayley » Tue Jun 18, 2013 3:17 pm

You're not the first to notice this, several others (and myself) have. The idea there was to reduce the impedance of those pads to the ground plane by making the connections as solid as possible.
The errata post and the latest revision of the user manual both mention this; however, we may yet change the design in the future given the number of comments about this.
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Re: Some holes difficult to solder

Postby junktronix » Tue Jun 18, 2013 3:50 pm

Wish I'd found the errata post earlier. It seems to cover all the notes I made during assembly. I'm pretty sure the impedance of a poorly soldered joint is worse than the impedance of a proper thermal relief :)
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Re: Some holes difficult to solder

Postby BlackX » Tue Jul 09, 2013 3:02 pm

First solder the pad to ground and look if the component stay fixed.
After trimming the leads clean with alcohol and inspect the joint if necessary resolder the joint.
It affects all ground pads little and big. I had to raise the temperature up to 350°C.
Good solder with leed helps. Leed free solder needs even higher Temperautes.
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Re: Some holes difficult to solder

Postby 2lostkiwis » Wed Jul 10, 2013 2:22 pm

junktronix wrote:Wish I'd found the errata post earlier. It seems to cover all the notes I made during assembly. I'm pretty sure the impedance of a poorly soldered joint is worse than the impedance of a proper thermal relief :)


I'd also add that it's probably not required that LEDs have low impedance paths :-)
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Re: Some holes difficult to solder

Postby alanford » Wed Jul 17, 2013 5:54 pm

If you can change the tip on your soldering iron, see if you can get what Hakko calls a "hoof" tip (at least that's what it's called on the Adafruit.com, it may also be called a bevel tip). Its got a very large flat surface at an angle to the tip. I used it by wetting it with solder and laying it right down on the solder pads. After a number of seconds everything soldered just fine (I was using a 70 watt iron, the Hakko FX-888 I think). Another trick that worked for the smaller pads was to heat the board a little bit with hot air before soldering. A hot-air rework station was suggested, but I used Sparkfun's Heaterizer XL-3000 heat gun, covering with aluminum foil anything I didn't want warmed up. Worked like a charm!
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