AMD uses SnAgCu solder balls for commercial-grade (XC) and automotive-grade (XA) BGA packages. In addition, suitable material are qualified for the higher reflow temperatures (250°C maximum, 260°C for dry rework only) required by Pb-free soldering processes.
AMD does not support soldering SnAgCu BGA packages with SnPb solder paste using a Sn/Pb soldering process. Traditional Sn/Pb soldering processes have a peak reflow temperature of 220°C. At this temperature range, the SnAgCu BGA solder balls do not properly melt and wet to the soldering surfaces. As a result, reliability and assembly yields can be compromised.
The optimal profile must take into account the solder paste/flux used, the size of the board, the density of the components on the board, and the mix between large components and smaller, lighter components. Profiles should be established for all new board designs using thermocouples at multiple locations on the component. In addition, if there is a mixture of devices on the board, then the profile should be checked at various locations on the board. Ensure that the minimum reflow temperature is reached to reflow the larger components and at the same time, the temperature does not exceed the threshold temperature that might damage the smaller, heat sensitive components.
This section provides guidelines for profiling Pb-free solder reflow. In general, a gradual, linear ramp into a spike has been shown by various sources to be the optimal reflow profile for Pb-free solders. This profile has been shown to yield better wetting and less thermal shock than conventional ramp-soak-spike profile for the Sn/Pb system. SnAgCu alloy reaches full liquidus temperature at 235°C. When profiling, identify the possible locations of the coldest solder joints and ensure that those solder joints reach a minimum peak temperature of 235°C for at least 10 seconds. Reflowing at high peak temperatures of 260°C and above can damage the heat sensitive components and cause the board to warp. Users should reference the latest IPC/JEDEC J-STD-020 standard for the allowable peak temperature on the component body. The allowable peak temperature on the component body is dependent on the size of the component. In any case, use a reflow profile with the lowest peak temperature possible. The following tables list the peak package reflow body temperature information by package size.
| Profile Feature | Convection, IR/Convection |
|---|---|
| Preheat ramp-up rate 30°–150°C | 2°C/s maximum 1°C/s maximum for lidless packages with stiffener ring |
| Preheat temperature soak time 150°–200°C | 60–120 seconds |
| Temperature maintained above 217°C | 60–150 seconds (60–90 seconds typical) |
| Time within 5°C of actual peak temperature | 30 seconds maximum |
| Peak temperature (lead/ball) | 230°C–245°C typical (depends on solder paste, board size, component mixture) |
| Maximum peak temperature (body) | 240°C–250°C, package body size dependent (see the specific Versal Device Data Sheet). |
| Ramp-down rate | 2°C/s maximum |
| Time 25°C to peak temperature | 3.5 minutes minimum, 5.0 minutes typical, 8 minutes maximum |
| Profile Feature | Convection, IR/Convection |
|---|---|
| Preheat ramp-up rate 30°–150°C | 0.5°C/s–1.5°C/s |
| Preheat temperature soak time 150°–190°C | 65–70 seconds |
| Temperature maintained above 217°C | 50–60 seconds |
| Maximum peak temperature (body) | 234°C–238°C, package body size dependent (see the specific Versal Device Data Sheet). |
| Ramp-down rate 240°–125°C | 1°C/s–2°C/s |
| Profile Feature | Convection, IR/Convection |
|---|---|
| Preheat ramp-up rate 30°–150°C | 0.5°C/s–1.5°C/s |
| Preheat temperature soak time 150°–190°C | 76–81 seconds |
| Temperature maintained above 217°C | 77–93 seconds |
| Maximum peak temperature (body) | 231°C–240°C, package body size dependent (see the specific Versal Device Data Sheet). |
| Ramp-down rate 240°–185°C | 0.7°C/s–0.8°C/s |
| Ramp-down rate 185°–125°C | 1.6°C/s–1.75°C/s |
