by Viktor Vogman, Power Conversion Consulting, Olympia, Wash., How2Power Today, May 15 2020
Focus:
The increase in server complexity has resulted in a growing need for better and easier
motherboard (MB) configurability. A new technology facilitates MB reconfiguration with a rework
grid array (RGA) interposer, which is a ball grid array or an IC package support structure with
embedded electric heaters. The heaters supply heat locally to reflow solder and thereby enable
attachment or detachment of the IC or the processor package. This RGA-based reconfiguration
method provides cost advantages over sockets or desoldering/resoldering equipment. The power
required to activate the RGA heater can be supplied from the MB power supply, e.g. a 12-V bus.
This article studies the electrical design of the RGA heater control (using an inductorless
topology) to make this circuitry highly efficient, as well as cost- and size-optimized. Issues
discussed include heater temperature sensing options, minimizing losses in the control switch,
choice of single or multiple heater zones, and experimental results.
What you’ll learn:
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