How to Efficiently Remove Components from Printed Circuit Boards

1
How to Efficiently Remove Components from Printed
Circuit Boards

• You may need to remove all the components from a
  printed circuit board for rework, repair,
  upgrade, salvage or other purposes. But how do
  you do it in the most efficient way? Its a
  simple process if you keep in mind that most
  printed circuit boards (PCBs) have both active
  and passive components that are attached to the
  PCB in one of two ways surface-mounted or
  through-hole.
• Surface mounted devices (SMDs) are electronic
  components that are soldered to the PCB surface
  by their miniscule metallic surface terminals.
  Common examples of SMDs are passive parts such as
  resistors are capacitors, or active parts such
  as ICs.
• Through-hole components have leads that are
  inserted through padded holes and are then
  soldered to the pads on the bottom side of the
  PCB. Common examples of through-hole components
  are resistors, capacitors, relays, inductors,
  transformers and more.
• To remove SMDs and through-hole components from a
  PCB, use the following procedure
• Preparation
• Don personnel protective equipment (PPE) such as
  safety glasses and gloves.
• Set the PCB on a work surface that is both
  horizontal and dry. It is important that the PCB
  is set on a truly horizontal surface when the
  PCB is heated, molten solder will be created and
  may move to adjacent

2

• pads or tracing when set on a non-horizontal
  surface, which may cause short circuits on the
  PCB.
• Removing SMDs
• Use a heat gun to remove the SMDs. After turning
  on the heat gun, position it approximately 15
  centimeters above the PCB with its nozzle
  pointed down. In short order, the heat will melt
  the solder flux of the SMDs that are beneath the
  nozzle of the heat gun. Quickly remove these
  components by utilizing a tweezers. Collect them
  in a tray. Repeat this procedure until all the
  SMDs are removed from the top side of the PCB.
• After you have removed all the SMDs, allow the
  PCB to cool for up to three minutes. Power down
  the heat gun and properly stow it away in a safe
  place.
• Removing Through-Hole Components
• Energize a soldering iron and sets its
  temperature to 450oC. Obtain a 6-inch length of
  copper desoldering braid.
• Select a desoldering starting point at the far
  edge of the board. Then touch the copper braid
  on top of a pad that as you place the tip of the
  soldering iron on the solder joint pad. In a
  matter of seconds, the solder flux should melt
  and flow into the copper braid. Follow this
  procedure for all pads.
• After you have completed desoldering on the pads
  on the reverse side of the board, flip the PCB
  over and repeat the process again using both the
  heat gun and the soldering iron to remove any
  other components and residual solder.

3

• When all SMD and through-hole components are
  removed, de- energize the soldering iron and
  properly secure it in a safe location.
• Clean Up
• Inspect the PCB and using swabs doused in
  alcohol, clean the pads on both sides of the
  PCB. After you have cleaned the pads, you should
  have removed all the components from the PCB.
• About Bittele Electronics
• Headquartered in Toronto, Canada, Bittele
  Electronics specializes in turnkey PCB assembly
  for electronics engineers requiring prototype or
  minimal volume PCBs. For more information, visit
  http//www.7pcb.com