Soldering Workshop

By: Diane Kim (Division Manager for E&C)

Verified By: Jordan Smallwood (Project Manager)

Approved By: Miguel Garcia (Quality Assurance)


Introduction

The Soldering workshop was focused on hand soldering. Based on the PCB designs of each project, the components that were to be hand soldered were the through-hole components, more specifically the connectors and the IR LEDs. Since we had access to a soldering iron, we practiced soldering based on the guide from Adafruit to understand how to solder. I have access to a PCB fabricating machine called the Othermill from Batam tools and printed out practice circuits for the group to practice on as well as provide connectors if needed.


Guide To Soldering

Required Tools

  • Solder Iron
  • Wet Sponge/Brass Mess
  • Solder
  • Wires
  • Through-Hole Components
  • Solder Sucker/Wick

First Step: Check Tools/Materials

Before you turn on the soldering iron, make sure to check whether the tip is clean or not. If the tip is not clean (when it is oxidized) it can prevent the tip of the soldering iron from heating up properly. To make sure that this doesn’t happen, we need to always make sure to clean the tip using the wet sponge and brass mesh and thin the tip after each use so the tip acts as a protective layer.

The type of solder also determines what temperature to set the iron on. If the solder is lead-based the temperature of the iron should be set to around 650 degrees Fahrenheit, and if the solder is lead-free it is best to set the temperature around 750 degrees Fahrenheit. The temperature setting is important to properly heat up the conductive pads and the wires or through-hole components.


Soldering

When the soldering iron reaches the desired temperature, the iron is placed in the joint of the pad and the component wire lead. The solder should first touch the iron and then to the wire lead and the pad for a secure connection. Then remove the iron and solder for it to cool. It is also important to make sure that the heat is not applied for too long to prevent overheating. A good solder is when the solder covers the whole pad and the wire lead and it has a slanted slope connecting the wire lead and the pad. It also looks smooth and shiny on the surface. If the solder is dark and is in a ball like shape that means that not enough heat or uneven heat was applied to the pads which are called the cold joint.


Making Mistakes:

Sometimes when the pads are so close, it can be shorted during the soldering process. To remove the excess solder, you can use a solder sucker or solder wick to remove the solder. The solder sucker sucks the solder out and the solder wick soaks up the excess solder.


Soldering Workshop:

The groups first went over the basics of soldering and then I provided practice boards so that they could practice. The practice board consisted of connectors that varied in the number of pinheads (8, 6, 4, 3). Female connectors were also provided to practice soldering.

Figure 1: Eagle Board file of the practice board for soldering

The practice board consists of 2 of each 8, 6, 4, and 3 pinhead connectors.

Figure 2: Photo of the practice board after printing and female connectors that are provided


Conclusion:

The group knew how to solder prior to the workshop but were able to practice to avoid making mistakes that would cost them the whole board. Since they were able to practice soldering on connectors which is what they will be soldering on for their PCB, it was more applicable to their projects.

When it comes to surface mount soldering, I went over the theory of how to apply the solder paste and how to bake the board; however, since I have access to a PCB fabrication machine that can print the solder paste and bake the board, we will be using that for the PCBs for our projects. The PCB fabrication machine that we are using is the V-one from Voltera.  


References:

The information about soldering is based off a tutorial on Adafruit:

  1. https://learn.adafruit.com/adafruit-guide-excellent-soldering/tools