reballing

Reballing is the process of removing solder balls from a Ball Grid Array (BGA) microchip and replacing them with fresh solder spheres. A BGA is a surface-mount integrated circuit with hundreds or thousands of small solder balls arranged in a grid on its underside, serving as both mechanical attachment and electrical connection to a printed circuit board. When those balls degrade, crack, or fail to make contact, reballing offers a way to salvage the component instead of discarding it.

The process begins with heating the component to melt the existing solder, then physically removing the old balls by scraping or wire-brushing the pad array. The bare pads are then cleaned, often with flux, to remove oxidation and residue. Fresh solder balls, typically 0.5 mm to 1.5 mm in diameter depending on the device, are positioned on each pad using a template or automated placement equipment. The assembly is reflowed in a controlled thermal profile: ramped to around 250°C, held briefly, spiked to the melting point of the solder alloy (usually 217°C for lead-free), then cooled. This forms clean, uniform solder connections.

When and why reballing matters

In energy systems, BGAs appear in power management circuits, inverters, and control modules where reliability is non-negotiable. Environmental stress, thermal cycling between ambient and operating temperatures, and mechanical vibration can cause the brittle solder joints to crack or lose contact. Field technicians or rework facilities perform reballing on valuable, hard-to-source components rather than replacing an entire circuit card. This is especially common in legacy equipment where exact replacement boards are no longer manufactured.

Reballing demands precision equipment: a controlled reflow oven, proper temperature profiling tools, and often an X-ray inspection system to verify that all balls have formed correctly and made full contact with their pads. Cheap or careless reballing is worse than useless; under-reflowed joints fail again within months, while over-reflowed joints can bridge to adjacent pads or damage the underlying substrate. The solder alloy chosen must match the original (lead-free SAC305 is standard for new work) and tolerate any subsequent thermal cycling the board will experience.

The term appears primarily in electronics rework and repair circles. It is distinct from rework, which refers to the wider category of soldering and component replacement, and from redistribution layer (RDL) processing, which is a manufacturing step on the silicon wafer itself. Reballing is a field or shop procedure, not a production process.