Vectronics VEC-1500K - Manual (Page 29)

24
LESSON 7
Soldering Applications
Most hand soldering involves constructing circuit boards and wiring them into
larger pieces of equipment. In this section, we'll cover the basic techniques used
for constructing boards. We'll also cover the soldering methods used for
installing jacks, switches, and connectors.
Circuit Board Evolution and Circuit Board Types
Circuit board technology has changed a lot over the years. Here's a "thumb-nail"
look at their evolution--along with a rundown of the kinds of boards you're likely
to encounter:
Single-Sided PC Boards: When printed circuit boards first came on the scene,
all wiring was etched onto a copper-coated side, and all components were
mounted on the opposite non-metalized side. The copper side was called the
solder-side
because all solder connections were made on that surface. The
opposite side was called the component-side. The board itself was called a
single-sided
PC board because only surface was metalized.
Double-Sided PC Boards: Over time, as miniaturization increased and RF
(radio frequency) construction techniques improved, designers began using
copper on both sides of the board for wire-traces and grounds. These became
known as a two-sided or double-sided boards. Although wiring was etched on
both sides, construction methods usually dictated that components be mounted
on one side only. Thus, the "component-side" and "solder-side" terminology
stuck--and is still used today. When traces needed to be "through-connected"
from one side to the other, this was done by soldering component leads on both
sides of the board, and also by installing short wires through the board called
vias.
Plate-Through PC Board: Eventually, techniques evolved for metal-plating
the inside surfaces of the holes drilled in the boards. These metallized holes
were called plate-throughs. Plate-throughs made electrical contact between pads
on each side of the board. This innovation eliminated the need for soldering
components on both sides and also eliminated the need for installing vias by
hand. That, in turn, made automated soldering of two-sided boards both cost-
effective and practical. A PC board with two etched surfaces and plate-through
holes is called a double-sided plate-through board.