Applications/Processing Guide
ADJUSTABILITY (OUTPUT VOLTAGE RATIO): The precision with
which the output voltage ratio of a device can be set to the
desired value.
Forced Hot Air Convection System
— Uses a multizone forced
air convection system with heat source panels using IR or other
type heating elements. Approximately 85% of the heating is
provided by free convection to reflow solder on exposed PC
boards.
Dual Wave System
— Utilizes two parallel solder waves. The
first is a turbulent wave followed by a laminar wave. The turbu-
lent wave is for small, constricted areas, while the laminar wave
removes solder projections.
Vapor Phase System
— Provides a single-zone condensation
heat source achieved with liquid fluorinated hydrocarbons that
have been brought to the boiling point to create a saturated
vapor zone. Heat is then released by the fluid’s heat of vapor-
ization as the vapor condenses on the product.
Soldering (Through-hole)
Two types of equipment are usually associated with through-
hole soldering:
Single Wave System
— Provides an inclined portion of the
solder wave for the PC board to pass over. The PC board is
positioned to bring many potential solder joints in contact with
the wave simultaneously for a short time for soldering.
Drag System
— Provides for PC boards to be dragged across
the surface of the solder pot. Soldered connections are made
during this operation.
PC Board Washing
Two types of equipment are usually associated with both SMT
and through-hole products.
Pressure System
— Accomplishes cleaning by directing sprays
of water under high pressure from multiple nozzles.
Flooding System
— Utilizes a combination of flooding (at
normal water pressure) and surfactant action for cleaning).
Soldering and Wash Processes
Figure 1 shows typical profiles any component may see during
a soldering and board washing operation. For details of materi-
al and process variables recommendations, see “Soldering and
Cleaning Processes”, page 76.
Solder
2
MECHANICAL TERMS
STARTING TORQUE: The maximum moment in the clockwise and
counterclockwise directions required to initiate shaft adjust-
ment anywhere in the mechanical travel.
STOP TORQUE: The maximum static moment that can be applied
to adjustment shaft at each mechanical stop for a specified
period of time without loss of continuity or mechanical damage
affecting operational characteristics.
SOLDERABILITY: The ability of the terminals to accept a uniform
coating of solder under specified conditions.
WELDABILITY: The ability of materials to be welded together under
specified conditions.
TERMINAL STRENGTH: The ability of the terminals to withstand
specified mechanical stresses without sustaining damage that
would affect utility of the terminals or operation of the trimming
potentiometer.
IMMERSION SEALED: The ability of the unit to withstand submer-
sion in acceptable cleaning solutions used in normal soldering
processes without performance degradation under specified
environmental conditions.
TRIMMER "ABILITIES"
When you are selecting components for a new design, you
typically take into account the environmental conditions that the
components will need to endure during the lifetime of the instrument
or device. Designers in the past have often overlooked the environ-
mental extremes of their own production lines, where the conditions
may be much more severe than anything encountered in actual end
use.
PROCESSABILITY
"Processability" refers to the ability of the unit to withstand the
production-line processes associated with the finishing steps on the
PC boards. Typically, both SMT and through-hole products are sub-
jected to similar PC board processing operations after preparation
for assembly. These operations can generally be summarized as
follows:
Wash
Flux
®
Pre-Heat
®
Solder
Flux
1st Pre-Heat
2nd Pre-Heat
2nd Stage Dryer
1
3
Air Knife
Rinse
Air Knife
Rinse
4
°C
5
Wash
®
Rinse
®
Dry
Air Knife
Rinse
1st Stage Dryer
Top Mounted
Thermocouple
Rinse
Bottom
Mounted
Thermocouple
Soldering (SMT)
Four types of equipment are usually associated with SMT
soldering:
IR System
— Uses a multi-zone infrared furnace with IR
elements heated to a temperature substantially above chamber
or product temperature. Energy is supplied to the product
primarily by IR radiation to reflow solder.
6
Minutes
Specifications are subject to change without notice.
88
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