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.
Consider these factors when determining optimal profile: solder paste/flux type, board size, component density, and component mix. Establish profiles for all new board designs using thermocouples at multiple locations on the component. If the board has a mixture of devices, check the profile at various board locations. Make sure the minimum reflow temperature reaches the larger components without exceeding the threshold temperature that damages the smaller, heat sensitive components.
This section provides guidelines for profiling Pb-free solder reflow. Various sources show that a gradual, linear ramp into a spike yields the optimal reflow profile for Pb-free solders. This profile yields 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 coldest solder joint locations and ensure they reach a minimum peak temperature of 235°C for at least 10 seconds. Reflow temperatures of 260°C and above can damage the heat-sensitive components and cause board warpage. Refer to the latest IPC/JEDEC J-STD-020 standard for allowable peak temperature on the component body. Component size determines the allowable peak temperature on the component body. Use a reflow profile with the lowest peak temperature possible. The following tables show peak package reflow body temperature 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 |
| 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–240°C, package body size dependent |
| 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 |
| 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 |
