IMPORTANT: The following component placement guidelines apply to all package types included in this guide (lidded, lidless, bare-die, etc.).
AMD device packages must be placed accurately according to their geometry outline. Positioning packages manually via hand mounting is not recommended.
Typical component placement accuracies of ±50 µ m can be achieved using standard pick and placement machine equipment with vision system. The PCB and the components are optically checked and measured and the components are placed on the PCB in specific programmed positions based on the PCB CAD information. The pick and placement machine vision system detects the fiducials on the PCB immediately prior to mounting the FPGA. Recognition of the packages is performed by the vision system, to ensure correct centering of the FPGA placement on the PCB pad array.
BGA packages with solder balls can self-align during the reflow process because of the solder high surface tension that enables the pulling and centering of the device, and where a slight offset of the placement is still allowed. For guidance, the maximum tolerable offset of device placement is around 30% of the pad diameter on the PCB for typical non-solder mask defined pads. This means that for device packages the solder ball to PCB pad misalignment must be better than 150 µ m to assure a robust mounting process. Generally, this is achievable using a wide range of modern pick and placement systems. The following setup conditions are important for the pick and placement systems:
• The pick and placement nozzle type should be sized to the dimensions of the AMD device. The nozzle needs to firmly hold the device package during the pick and placement stage. The appropriate nozzle type for the device package can be chosen from the manual provided by the pick and placement equipment company.
• The ball recognition capabilities of the placement system should be used and package outline centering should be avoided. This eliminates the solder ball to package edge tolerances of the package. Refer to the specific package outline drawing for details.
• To ensure the proper identification of the device package by the vision system, a suitable lighting system and the correct choice of the features of the measuring method are essential. The most suitable settings can be chosen from the manual provided by the pick and placement equipments company.
• To avoid solder bridging or solder smear, ensure the proper placement force of the device package during placement on the PCB. Excessive placement force can lead to excess solder paste and cause solder bridging. However, a slight placement force can lead to insufficient solder paste contact between the device package solder balls and the solder paste, causing solder defects including open solder joints, badly centered packages, or even head-in-pillow (HIP) defects.