User's Manual

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Notes:
More details of iWRAP software and it’s features can be found from iWRAP User Guide
which can be downloaded from www.bluegiga.com
.
10. SOLDERING
10.1 Reflow Soldering
The soldering profile depends on various parameters necessitating a set up for each
application. The data here is given only for guidance on solder re-flow. There are four
zones:
1. Preheat Zone - This zone raises the temperature at a controlled rate, typically 1-
2.5°C/s.
2. Equilibrium Zone - This zone brings the board to a uniform temperature and also
activates the flux. The duration in this zone (typically 2-3 minutes) will need to be
adjusted to optimize the out gassing of the flux.
3. Reflow Zone - The peak temperature should be high enough to achieve good
wetting but not so high as to cause component discoloration or damage. Excessive
soldering time can lead to intermetallic growth which can result in a brittle joint.
4. Cooling Zone - The cooling rate should be fast, to keep the solder grains small
which will give a longer lasting joint. Typical rates will be 2-5°C/s.
5. Solder Re-Flow Profile for Devices with Lead-Free Solder Balls
Composition of the solder ball: Sn 95.5%, Ag 4.0%, Cu 0.5%
Key features of the profile:
• Initial Ramp = 1-2.5°C/sec to 175°C±25°C equilibrium
• Equilibrium time = 60 to 180 seconds
• Ramp to Maximum temperature (250°C) = 3°C/sec max.
• Time above liquidus temperature (217°C): 45-90 seconds
• Device absolute maximum reflow temperature: 260°C
Devices will withstand the specified profile. Lead-free devices will withstand up to three
reflows to a maximum temperature of 260°C.