Navman LA000645 GPS Receiver User Manual


 
Temperature
o
C
Time Sec
260
3000
Pre-heat
Reow
Cool-down
Liquidus Temp.
Peak Temp.
Pb Solder
Pb-free Solder
Heat
LA000605D © 2007 Navman New Zealand. All rights reserved. Proprietary information and specications subject to change without notice.
16
Figure 4-1: Sample Lead and Lead free reow prole
4.1.5 Coating
The nal PCB may be selectively coated with an acrylic resin, air / oven cured conformal
coating, clear lacquer or corresponding method, which gives electrical insulation and
sufcient resistance to corrosion.
4.1.6 Post reow washing
It is recommended that a low residue solder paste is used to prevent the need for post reow
washing. If a washing process is used, an aqueous wash is not recommended due to the
long drying time required and danger of contaminating the ne pitch internal components.
4.1.7 Pre-baking
The modules will be delivered on a tape and reel package, and sealed in an airtight bag. The
MSR (Moisture Sensitivity Rating) is 3, therefore they should be loaded and reowed within
168 hours (7 days). If the modules are in ambient humidity for longer than this, a pre-baking/
drying process will be required.
4.1.8 Rework
It is recommended that no more than 2 reow cycles are performed and that the maximum
reow temperature recommended by the solder paste manufacturer is not exceeded. The
maximum ramp-up rate of 3
o
C/sec for leaded solder or 4
o
C/sec for lead free solder should
not be exceeded.
Navman recommends that rework and repair is carried out in accordance with the following
guidelines:
• IPC-7711 Rework of Electronic Assemblies
• IPC-7721 Repair and Modication of Printed Boards and Electronic Assemblies
For proper removal of the part, special nozzles should be used for local heating of the part
to avoid reow of adjacent parts. The PCB assembly should be preheated to about 75° C
from the bottom using convective pre-heaters and the preheated nozzle should be lowered