AN7301 - Synergy Microwave Corporation

GUIDELINE FOR AUTOMATED REFLOW SOLDERING PROCESS FOR PRODUCTS
CONTAINING WIREWOUND TRANSFORMERS
Forward
The guidelines provided in this application note consider the guidelines of JEDC J-STD-020 and describe
the basic surface-mounting assembly requirements for solder reflow of wire wound transformer based
products manufactured by Synergy Microwave Corporation. Optimum yields are achieved by careful
optimization of the heating profile to allow for package size limitations.
Peak Reflow Temperature
Determining the maximum allowable peak reflow temperature is a process that involves consideration of
the package volume and thickness for Pb-free soldering processes as described in Table I below:
Table I.
Package peak reflow temperature (Tp)
Reflow
Process
Thickness
Pb-Free
>2.5 mm
Volume
<350 mm
3
230oC +0/-5oC
>350 mm3
>2000 mm3
225oC +0/-5oC
225oC +0/-5oC
tP
Tp
Critical Zone
TL to TP
Temperature
Ramp-up
TL
tL
Tsmax
Ramp-down
Tsmin
tS
Preheat
25oC
t 25oC to Peak
Time
Figure 1.
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Temperature reflow profile
AN7301 Rev. B 11/02/09
Table II. Reflow profile parameters
Reflow Profile Feature
Average ramp-up rate
(Tsmax to Tp)
Preheat
-Minimum Temperature (TSmin)
-Maximum Temperature (TSmax)
-Time (TSmin to TSmax)
Time maintained above:
-Minimum Temperature (TL)
-Time (tL)
Peak Temperature (Tp)
Time within 5oC of actual peak
temperature (tp)
Ramp-down rate
Time at 25oC to Peak
Temperature
Pb-Free Assembly
3oC/second max.
150oC
200oC
60 – 180 seconds
217oC
60 – 150 seconds
Per Table I
10 - 20 seconds max.
6oC/second max.
8 minutes max.
Consideration for maximum reflow temperature limits – One reflow pass
For technical assistance contact:
Synergy Microwave Corporation
201 McLean Boulevard
Paterson, NJ 07504
Tel. 973-881-8800
Fax 973-881-8361
Email: info@synergymwave.com
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AN7301 Rev. B 11/02/09
- Recommended Solder Reflow profile for Pb-Free Process -
Temperature
Tp
Tp=230oC
Ramp-up to tp
60 sec
180oC
220oC
30 sec
(+/-10 sec
Reflow)
150oC
1 to 5oC per sec
Ramp down
90 (+/-30 sec)
Preheat
25oC
Heating Time (Sec)
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AN7301 Rev. B 11/02/09