Soldering RXD, TXD and GND to Ben NanoNote

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[edit] Purpose

One wants to solder[1] extension wires for BEN Nanonote’s serial console test points. (RXD, TXD & GND)

Since the Ben has that 3 test points (RXD, TXD & GND), it originally works as TEST POINTs on temporarily experimental or measurable purpose NOT permanently extendable one. Its original trace layout doesn’t allow you to do this under improper soldering method or carelessness. But if you still want to use serial port for a long while, this article can give you some hints.

[edit] Tool & Material

  • Soldering Station with a suitable conical type of soldering tip [2]
  • Soldering Wire 0.5Φ diameter [3]
  • Wire-Wrapping Wire 30AWG [4][5]
  • Multi-function wire stripper [6]

[edit] Frequent Failures When Soldering

Figure 1.
  • Test points ( Pads ) are broken from pcb surface
  • Trace with Test Point is pull out

With improper soldering method or carelessness, you probably get either both or one of them. Knowledge about Soldering

Since the iron soldering tool can easily let you join two metallic surfaces into one, you need to be careful about your soldering head temperature, how many seconds you use and how about your craftsmanship you have. Before you start to do the following steps, you can also check the physical theory a little bit or ask anyone possessed of senior soldering skills to help you.

Through [1], you can see more soldering articles for your reference. Also you can check here[7] to know HOW TO SOLDER first.

[edit] Steps

[edit] Soldering Accessories

Figure 2.
Figure 3.
A 900M-T-1 size of soldering iron tip can be suitable for this process. You

can choose a tip marked with V (1 and 3) as following figure. The tips marked with X (2 and 4) in figure 2 are not recommended.

A 0.5mm diameter soldering wire is better.

Figure 4.

Also using a 30AWG of wire wrapping wire or equivalent AWG wire is recommended.

Figure 5.

Why choose such a tiny diameter of accessories? Please see next figure and you will easily realize. Unless you are an expert with great craftsmanship in the field of soldering, I do really recommend you use them as it will make it a lot easier.

Figure 6.

[edit] Clean up test points and wires

The TXD (TP75) and RXD (TP74) are shown as below. Or see Serial_console[8] to understand their location. Clean up the surface of test point and wires first, you can just follow “ 2. SURFACE PREPARATION: CLEAN” instructions of [7] to do this step. Novices can make the mistake of overheating the parts as they try to force the solder to stick. This will usually result in irreversible damage and force you to scrap pads, trace or even BEN Nanonote.

Figure 7.
Figure 8.

[edit] Tinning

Contacts of both test points and wires must be tinned before attempt to solder. So now do tinning process on 3 test points and terminal of three wires as next figure as well. Some wire wrapping wire already have been tinned on its surface, you can just use a wire stripper to strip away the tip of the insulation to expose the copper wire within. Otherwise you must lightly coat it with solder. You must also tin the tip of the iron to help conduct heat to the components.

Figure 9.

[edit] Applying Heat and Solder

Before doing this step of real solder you can reference this video[9] to see how solder will be the better. “With the tinned soldering iron in hand, you are now ready to heat the components. Rest the iron tip on both the wire lead and the PCB. It will only take one or two seconds to heat the components up. Once you have heated up the wire and the circuit board, solder can be applied. Touch the tip of the strand of solder to the heated wire lead and the solder pad on the circuit board, but not to the tip of the iron. At this point, the solder will flow freely around the wire lead and the pad. Once the surface of the pad has been completely coated, you must stop adding solder and then, quickly remove the soldering iron. Do not move the newly formed joint for a few seconds until the solder cools down and becomes solid. Moving the joint at this point will cause a formation of a cold joint.”

Figure 10.

[edit] Clean up

Clean up again on all soldered area.

[edit] Fixed by glue or other adhesive tape

Using any adhesive tape or glue is to protect wire-wrapping wires away from heavy extra-loading forced to bend wires, pull out test points or break trace shown as figure 1. If you’d prefer to use usb power rather than battery, you can just do like as following figure or use adhesive tape to protect those three soldered point.

Figure 11.

[edit] References

  8. File:Ben_nanonote_serial2.jpg
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