Datasheet

13. Reflow Profile Information

This chapter provides guidelines for reflow processes in getting the Microchip module soldered to the

customer’s design. For more information on reflow process guidelines, refer to Solder Reflow

Recommendation Application Note (DS00233D).

13.1 Storage Condition

13.1.1 Moisture Barrier Bag Before Opening

A moisture barrier bag must be stored in a temperature of less than 30°C with humidity under 85% RH.

The calculated shelf life for the dry-packed product shall be 12 months from the date the bag is sealed.

13.1.2 Moisture Barrier Bag Open

Humidity indicator cards must be blue, <30%.

13.2 Printing Process

The printing process requires no significant changes compared to Sn/Pb solder. Any guidelines

recommended by the paste manufacturers to accommodate paste specific characteristics should be

followed. Post-print inspection and paste volume measurement is very critical to ensure good print quality

and uniform paste.

13.3 Baking Conditions

This module is rated at MSL level 3. After a sealed bag is opened, no baking is required within 168 hours

so long as the devices are held at ≤30°C/60% RH or stored at <10% RH.

The module will require baking before mounting if:

• The sealed bag has been open for >168 hours

• Humidity Indicator Card reads >10%

• SIPs need to be baked for 8 hours at 125°C

13.4 Soldering and Reflow Condition

The optimization of the reflow process is the most critical factor to be considered for lead-free soldering.

The development of an optimal profile should take into account the paste characteristics, the size of the

board, the density of the components, the mix of the larger and smaller components, and the peak

temperature requirements of the components. An optimized reflow process is the key to ensuring a

successful lead-free assembly and achieves high yield and long term solder joint reliability.

Temperature Profiling

Temperature profiling should be performed for all new board designs by attaching thermocouples at the

solder joints, on the top surface of the larger components, and at multiple locations of the boards. This is

to ensure that all components are heated to a temperature above the minimum reflow temperatures and

the smaller components do not exceed maximum temperature limit. The SnAgCu solder alloy melts at

~217°C, so the reflow temperature peak at joint level should be 15 to 20°C higher than melting

ATWINC15x0

Reflow Profile Information

Datasheet

DS70005304C-page 37