By John D. Collier
BUILD A CIRCUIT BOARD
ASSEMBLY JIG
I spend a considerable amount of time assembling and soldering circuit boards for my
profession, as well as a hobby. One of my biggest frustrations has always been securing the
PCB in such a way that it cannot move or vibrate, but still allows plenty of access for the
soldering iron. Over the years, I have purchased — and been disappointed with — various
types of circuit board vises and fixtures. The ubiquitous “third hand” gripper was too flimsy.
Others had jaws specifically for circuit boards, but I found them to be too deep or
improperly sized. Most could not hold more than one PCB at a time. And there was one
feature in particular that I was looking for: a reliable way to hold through-hole components
in place, upside down, while I soldered on the other side of the board. This article describes
my solution.
■ FIGURE 1. The completed
assembly jig, with side supports
in use.
THE DESIGN
I loosely based my design on photos I had seen of
professional circuit board reworking equipment (costing in
the hundreds or even thousands of dollars). These systems
use a piece of soft foam rubber to hold components in
place, allowing soldering work to be done on the opposite
side. I decided to use T-slotted extruded aluminum for the
jig frame, from 80/20, Inc. ( www.8020.net). The T-slot
system is very versatile, as T-nuts can be used to mount
28 September 2011
components at any location on any
of the four sides.
Two notched rails were
fabricated which capture the circuit
board(s) and can be adjusted as
necessary in the T-slots. The foam
is attached to a backer plate which
is inserted through the opposite
side of the jig and applies slight
pressure to the circuit board.
Knowing that this foam would be
installed and removed frequently, I
chose to use quick-release toggle
clamps to hold it in place.
After trying out the jig with
several different PCBs, I found that
certain large or odd-sized
components had to be manually
held in place while being soldered.
This proved difficult since the parts
are normally underneath the jig
during soldering. My solution was
to install two strips to the front of the jig using T-nuts
which are normally parallel to the extrusion, but can be
rotated 90 degrees to provide an extra set of feet. The jig
can then be set on its side, allowing access to both sides
of the circuit board. Figure 1 shows the jig in this setup.
FABRICATION and
ASSEMBLY
Most of the components were purchased from
McMaster-Carr ( www.mcmaster.com); refer to Table 1