Improving Your Wave Soldering: Technologies
Improving Your Wave Soldering: Technologies
Improving Your Wave Soldering: Technologies
IMPROVING YOUR
WAVE SOLDERING
Igmar Grewar
Technical Director
PEM Technologies
Wave Soldering
Conveyor
PCB transported over
the wave
Component preparation
Insert components
Apply Flux
Preheat PCB
Soldering
Cool down
Selective Pallets
Fluxing
Why do we need flux?
Prevents oxidation
Acts as a wetting agent
Spray fluxing
Quantifiable application of
the flux deposit (SPC)
No in-process QC of the
flux
No thinner consumption
Direct application from
can
Reduced flux
consumption
No flux drippings over the
preheat zone
Flux Types
Alcohol based (100% VOC)
Flux Types
Low-VOC (40% water / 60%
alcohol)
Modest in preheat requirements
Safer to the environment
Can be applied by spray or foam
High residue safety and wide process window
Flux Types
Water based (100% VOC-free)
More soldering power
Environmentally safe
Non-flammable
Preheat
Functions of Preheating
Preheat
Types of Preheating
Infra Red elements
Quartz elements
Forced Convection
Adhesive
Temperature
Strips
Infrared
Thermometer
Picture courtesy of
www.tempstrips.com
Incorrect Preheat
Preheat too high or too long may break down the flux
activation system and cause shorts / icicles
Preheat too low may cause problems such as skips
or unwanted residues left on the PCB
Soldering Phase
Wetting Phase
Wicking Phase
Drain Phase
ing
in
Drain
Wick
ing
Wett
W
av
e
- >>
PCB
Soldering Phase
Nominal angle = 7
Contact Width = 20 to 40mm wide for Delta Wave
Contact Width = 15mm wide for Chip Wave
Dwell time Tin/Lead = 3.5 sec @ 235C solder pot temperature
Dwell time Tin/Lead = 2.5 sec @ 250C solder pot temperature
Dwell time Pb-Free = 2 to 5 seconds @ 260-270C solder pot
temperature, depending on the application
Conveyor speed = 0.8 1.5 m/min
Conveyor speed (m/min) = Contact width (cm) x Dwell time (sec)
Wave height = 1/3 2/3 of PCB thickness
High temperature glass plate is used to measure contact width and
parallelism to the wave
idth
w
t
c
a
Cont
Turbulent wave
Can be added in addition to the Delta Nozzle
High Kinetic Energy
Avoids shadowing
Solder Alloy
Lead Containing Alloy Sn/Pb
Solder Alloy
4 Popular choices for Lead-Free
SAC (Tin/Silver/Copper)
SAC + X (Tin/Silver/Copper + X)
SnCu (Tin/Copper)
SnCuNi (Tin / Copper / Nickel)
Solder Alloy
SAC
Solder Alloy
SAC + X
Solder Alloy
SnCu
Tin / Copper
Sn99.3/Cu0.7
Melting point of 227C (Eutectic alloy)
No silver content - lowers alloy cost
Lower tendency to leach copper - less loss of
conductive copper in tracks and pads
Poor fluidity at typical lead free temperatures
Poor through-hole filling and forming of solder
bridges between components
Solder Alloy
SnCuNi
Cooling Phase
Nitrogen or Not?
Displaces oxygen
Reduced dross formation
Increase surface tension
Improved flow of solder
Better wetting
Bridges
Insufficient
Hole Fill
Blowholes
X
X
X
X
Excessive flux
Flux density too low
Flux density too high
Solder
Balls
Solder is contaminated
Uneven or erratic solder wave
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PEM Technologies
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