Soldering JTAG connector with Element14(Embest) version BBB failed

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1

Hi,

I tried to solder ARM20cTI20 JTAG connectors with Element14’s BBB but failed, twice (hence two boards broken). After some investigations, I think it’s not my fault but is manufacturer’s problem. Element14’s version and CircuitCo’s version are really different in this issue.

As you may know, BBB hasn’t JTAG interface on board unless you manually solder an extra ARM20cTI20 connector to its P2. There’re some tutorials on how to do that:
http://www.tincantools.com/wiki/Flyswatter2_BeagleBone_Black_How_To
https://www.youtube.com/watch?v=7JmHn7aN2FU

I have lot of experiences in soldering and never failed before. But this time is different. Although I strictly followed these tutorials, no matter how long I keep the soldering iron on the connector’s pins to heat adherent solder, the solder on the pin will never glue with the P2. I tried many times and some other methods (even with different kinds of solder irons) but stilled no success. I also tried to directly paste some solder to P2 but it’s pretty hard to adhere to. Some solder even became sphere other than adhere the bottom pins. Anyway, now two boards’ P2 were destroyed while two ARM20cTI20 connectors was consumed away.

After carefully compare images/video in tutorials with the boards I have, I found the main difference is, there isn’t any solder covered P2 pins in my boards.

Let’s take a look at Adafruit’s pictures on BBB:
CircuitCo’s version: http://www.adafruit.com/products/1876 (out of stock)
Element14’s version: http://www.adafruit.com/products/1996

And in SeeedStudio:
CircuitCo’s version: http://www.seeedstudio.com/depot/BeagleBone-Black-p-1505.html (not rev C)
Element14’s version: http://www.seeedstudio.com/depot/Embest-BeagleBone-Black-RevC-Singleboard-Computer-p-1860.html

Take a look at P2 on the back of the board. There’s a huge difference that CircuitCo’s P2 pins are covered by solder while Element14’s are not. Note that all tutorials used CircuitCo’s version. I also highly doubt Element14’s pins are covered by some solder mask which prevent the solder’s adherent.

My question is,

  1. Is there anyone who successfully soldered it on Element14’s BBB before? If you are, how do you achieve that?

  2. Is there any way to buy CircuitCo’s BBB rev C? At least Amazon, Adafruit, SeeedStudio, Sparkfun are not. MakerShed’s picture is CircuitCo’s but it hasn’t any manufacturer information. Consider that Sparkfun’s picture is also CircuitCo’s but their products are Element14’s, I don’t think picture is trustworthy.

Thanks your guys!

  • Claud
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I successfully soldered a JTAG connector to an Element 14 rev C board on my first attempt and I am by no means a pro with a soldering iron. I placed a small amount of solder on the bottom side of the connector first. Then I held the connector in place with a clamp so that there was pad showing off the end of each foot of the connector. I had my soldering iron hot enough to melt the solder in less than a second. I also dabbed on extra solder quite liberally at the toe of each foot onto the exposed pad. I removed the clamp after the first couple o pins so that I could get at the pins better. Then used solder wick to remove all the excess solder. There were at least 3 places with solid bridges. I inspected with 20x magnification. Then removed the tiny bridges I didn’t see before with more solder wick. Cleaned up with isopropyl alcohol. It’s not exactly pretty but worked on the first try.

Later tonight I can tell you the exact solder I was using and the temperature I had my soldering iron set to.

3

I just checked my settings. I have my iron set to 430C / 806 F and haven’t touched it since soldering that JTAG connector last week. Yeah. So very hot. Don’t leave it sit on the board at that temp. I figured a fast dab at high temp is better than letting it sit at lower temp though. Maybe I’m wrong. Like I said, I’m not a pro with the soldering, but it worked for me on the first try. Before I got my nice soldering iron I had problems getting connectors soldered onto another board because my iron wasn’t getting hot enough. I don’t have that problem anymore. :slight_smile:

My solder is Kester 44 Rosin Core Solder 60/40 .031.

Tom Olenik

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I just checked my settings. I have my iron set to 430C / 806 F and haven't
touched it since soldering that JTAG connector last week. Yeah. So very
hot. Don't leave it sit on the board at that temp. I figured a fast dab at
high temp is better than letting it sit at lower temp though. Maybe I'm
wrong. Like I said, I'm not a pro with the soldering, but it worked for me
on the first try. Before I got my nice soldering iron I had problems
getting connectors soldered onto another board because my iron wasn't
getting hot enough. I don't have that problem anymore. :slight_smile:

My solder is Kester 44 Rosin Core Solder 60/40 .031.

OK, several things here:

1) 63/37 is eutectic for solder, and has the lowest melting point. It
goes from liquid to solid and does not have a plastic phase (good).

2) 700 degrees is normal, and 600 is used for sensitive devices.

3) the amount of power that your tip can deliver (not necessarily the
temperature) determines the size of the joint you can heat and
successfully solder

4) clean is the key, a freshly tinned tip (clean and can transfer heat
well) is much better than an oxidized tip.

5) better to use a brass sponge than a wet one. Less thermal shock to
the tip.

Harvey

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https://specialcomp.com/beaglebone/

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Thank you Tom and Harvey! I’ll try again with higher temperature (800 or even more higher till it melts) as well as adopt Harvey’s suggestions. Result will be reported in this thread.

I used lead-free .022 in 700 degree. Temperature is one of a few factors I haven’t adjusted in those attempts for not damaging the board.

Also I’ve found CircuitCo version in Jameco Electronics.

7

Thank you Tom and Harvey! I'll try again with higher temperature (800 or
even more higher till it melts) as well as adopt Harvey's suggestions.
Result will be reported in this thread.

Ah, no, more temperature is not always what's needed.

Too cold and it never melts. Too hot and it damages the board and
what you're soldering. For leaded solder, 600 degrees is fine for
small sensitive parts, 700 degrees for standard parts, and you almost
never need 800 degrees.

Try a few joints with the solder and just solder a few pieces of wire
together, say 22 gauge or so. That gives you the practice you may
need for lead free solder (behaves differently).

I used lead-free .022 in 700 degree. Temperature is one of a few factors I
haven't adjusted in those attempts for not damaging the board.

800 degrees is a bit too hot. There's a bit of a touch to it, as to
how to solder and how not to. You want the solder to "flow" and to
"wet" the joint as if it were water.

I'd see what the melting point of your particular lead free solder is,
and then see what the recommended iron temperature is as well.

Harvey

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Hi Harvery,

700 dgree can melt lead-free solder directly very well – that’s how I adhere a layer of solder to connector pins. Then I put connector on top of P2 on the board and heat the pins for making the solder melt and connect joint just like the video. But the solder between pins and P2 won’t melt and none of it will adhere to the P2 even I heated 4-6 seconds in 700 degree. Note that I cleaned the solder iron with tip tinner and brass sponge before this step.

Another way is just like you said (hope my understanding is correct) to heat some solder and let it flow to the pin and wet the joint. I tried. But the solder flow won’t adhere to the P2 but just accumulated on the pin till bridge with adjacent pin.

Do you have any comment on this situation?

Thank you so much!

9

Hi Harvery,

700 dgree can melt lead-free solder *directly* very well -- that's how I
adhere a layer of solder to connector pins. Then I put connector on top of
P2 on the board and heat the pins for making the solder melt and connect
joint just like the video.

This is called (or was) "sweat soldering" it does work, but may not
be the best at times. No problem though.

But the solder between pins and P2 won't melt

What may be happening is that the solder on P2 is protected by a layer
of something, either oxide, or solder mask, or the like. I'd take a
small xacto knife or equivalent, and gently scratch one of the pads to
clean the surface. You want to stay in the plating area (assuming
that this is solder plated. Did you use flux? Liquid flux is
generally very useful in this kind of situation. You should be able
to melt the solder and let it flow onto the board land (the contact
area), without a pin there. If the solder just beads up, then you're
not getting any heat transfer to the pad, or the pad is protected.

I've had badly oxidized pads not take solder, and some plating on
boards will not accept solder (nickel, if I remember it). In that
case, some very gentle abrasion of the plating may expose the copper.
This is a crude solution, though. You could also try cleaning the
pads with a pencil eraser. It's quite abrasive and should not be used
for edge contacts (it will remove gold plating very easily).

and none of it will adhere to the P2 even I heated 4-6 seconds in 700
degree. Note that I cleaned the solder iron with tip tinner and brass
sponge before this step.

Generally, what you do is avoid the tip tinner unless you're losing
the tinning on the tip (solder won't adhere to the tip itself). I
normally don't use it or need it. Then you add solder, just a bit, to
the tip, use the sponge to clean it (and any oxides) off, then solder.
You can add a tiny bit of solder to the tip, which forms a tiny drop
there, and when put to a joint, will help heat transfer.

The steps are generally 1) clean the tip, 2) do the joint, 3) put the
iron back (it doesn't need to be cleaned at this point, the excess
solder actually tends to protect the tip).

Another way is just like you said (hope my understanding is correct) to
heat some solder and let it flow to the pin and wet the joint. I tried. But
the solder flow won't adhere to the P2 but just accumulated on the pin till
bridge with adjacent pin.

Then there's something there that the solder won't wet. There might
be a coating over the connector.

Do you have any comment on this situation?

Just did, it's an odd situation, since most of the boards are
manufactured to enable you to solder to selected areas, and the pads
for such a connector site would be ready to solder to.

Mine's a circuitco board, so I can't help with trying.

If you have some leaded solder, I'd try that. I'd also get a tube of
flux, you want the Kester RMA flux, which would be available at places
like Mouser or Digikey or Avnet (not sure about Jameco). This flux is
quite helpful for doing surface mount soldering (I do that a lot...).

Harvey

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Lead free. High temp neede to melt it.

Gerald

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thanks for verification this fix is more troubles than its worth I bought parts but decided buying a BBW was easier

12

Hi guys,

Followed Tom and Gerald’s suggestions, I tried it again by 800F with the lead-free solder. This time everything go well just like the tutorials and it works now!

Many thanks to all of you!

  • Claud