AMD uses SnAgCu solder balls for BGA packages. In addition, suitable package materials 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.
Table: Pb-Free Reflow Soldering Guidelines for Package Sizes Up to 45 mm x 45 mm and This Figure provide guidelines for profiling Pb-free solder reflow for package sizes up to 45 mm x 45 mm. Table: Pb-Free Reflow Soldering Guidelines for Package Sizes Greater than 45 mm x 45 mm and Up to 55 mm x 55 mm provides guidelines for package sizes greater than 45 mm x 45 mm and up to 55 mm x 55 mm. Table: Pb-Free Reflow Soldering Guidelines for Package Sizes Greater than 55 mm x 55 mm provides guidelines for packages sizes greater than 55 mm x 55 mm. 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 Figure ). 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. Refer to Table: Peak Package Reflow Body Temperature for AMD Packages (Based on J-STD-020 Standard) for peak package reflow body temperature information. In any case, use a reflow profile with the lowest peak temperature possible.
|
Reflow Profile |
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 data sheet under UltraScale Device Data Sheets ) |
|
Ramp-down rate |
2°C/s maximum |
|
Time 25°C to peak temperature |
3.5 minutes minimum, 5.0 minutes typical, 8 minutes maximum |
|
Reflow Profile |
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 (see the specific data sheet under UltraScale Device Data Sheets ) |
|
Ramp-down rate 240°–125°C |
1°C/s – 2°C/s |
|
Reflow Profile |
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 (see the specific data sheet under UltraScale Device Data Sheets ) |
|
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 |
|
X-Ref Target - Figure 7-2 
|
|
Package |
Product Category |
Peak Package Reflow Body Temperature (1) |
JEDEC Moisture Sensitivity Level (MSL) |
|---|---|---|---|
|
FBVA676 FFVA676, FFVB676 SBVB484 , SBVC484 SFVA784, SFVB784 |
XC |
Mass reflow: 250°C Dry rework: 260°C |
4 |
|
UBVA368 FBVA900 FFVD900, FFVE900 FFVA1156 FFVA1517, FLVA1517, FFVC1517, FFVD1517, FLVD1517, FFVE1517 FFVA1760, FFVB1760, FLVB1760, FFVE1760, FFVJ1760 FLVD1924, FLVF1924, FLGF1924 FFVA2104, FLVA2104, FLGA2104, FHGA2104 FFVB2104, FLVB2104, FLGB2104, FHGB2104 FFVC2104, FLVC2104, FLGC2104, FHGC2104 FLGB2377 FLGA2577 FLGA2892 |
All |
Mass reflow: 245°C Dry rework: 260°C |
4 |
|
VSVA1365 FSVJ1760 FSVH1924 FSGD2104, FIGD2104, FSVH2104 FSGA2577 FSVH2892, FSVK2892 FSVA3824 , FSVB3824 |
All |
Mass reflow: 240°C Dry rework: 260°C |
4 |
|
RBA676, RFA1156, RLD1517, RLF1924 FFRB676, SFRB784 FFRA1156, FFRC1517, FFRE1517 FLRA2104, FLRB2104, FLRC2104 |
XQ (2) |
Mass reflow: 225°C Dry rework: 235°C |
4 |
|
Notes: 1. See the specific data sheet under UltraScale Device Data Sheets for the most up-to-date specifications. 2. For devices with the Pb-free signifier in the package name (labeled as Q vs. V) use the temperatures and MSL listed for the XQ product category. |
|||
For sophisticated boards with a substantial mix of large and small components, it is critical to minimize the Δ T across the board (<10°C) to minimize board warpage and thus, attain higher assembly yields. Minimizing the Δ T is accomplished by using a slower rate in the warm-up and preheating stages.
It is also important to minimize the temperature gradient on the component, between top surface and bottom side, especially during the cooling down phase. The key is to optimize cooling while maintaining a minimal temperature differential between the top surface of the package and the solder joint area. The temperature differential between the top surface of the component and the solder balls should be maintained at less than 7°C during the critical region of the cooling phase of the reflow process. This critical region is in the part of the cooling phase where the balls are not completely solidified to the board yet, usually between the 200°C–217°C range. To efficiently cool the parts, divide the cooling section into multiple zones, with each zone operating at different temperatures.
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, as shown in This Figure and This Figure (thermocouple pictures). 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.
