#directdriveindexingtable

Motorized Indexing Rotary Actuator Used in IC Test Handlers Industrial Automation — Semiconductor & Electronics

An IC test handler moves each device under test from the input tray to the test socket. It sorts the device after the test result comes back. A Motorized Indexing Rotary Actuator sits at the heart of this transfer. The turret-style hollow rotary table rotates a ring of test sites between stations. It must place each device on the socket contacts within microns every cycle. When this rotation drifts even slightly, pin damage and false test results follow. Modern IC packages carry contact pitches as fine as 0.25mm. As a result, the Motorized Indexing Rotary Table that drives the turret cannot tolerate angular error at any index step. The precise positioning hollow rotary table holds repeatability in the arc-second range. The device lands on the socket pins in the same orientation every time. Consequently, spring-pin contactors inside the test socket make clean, repeatable contact. They no longer skate across the pin tips and wear them down early.  

Technical Comparison: Motorized Indexing Rotary Table vs. Standard Turret

Parameter

Motorized Indexing Rotary Table

Standard Indexing Turret

Repeatability Arc-second range Several arc-minutes typical Center bore Through-shaft for vacuum and signal lines External routing required Drive type Direct-drive torque motor Gear-reduced servo motor Thermal stability Stable bearing preload across temp range Preload shift under thermal cycling Settling behavior Fast lock, minimal index time Slower settling, backlash present Encoder type High-resolution absolute encoder Incremental, requires homing cycle Pin contact wear Reduced lateral scrub on socket pins Higher scrub from angular drift Index time defines test handler throughput directly. Engineers call the non-test portion of the cycle the index time. A shorter index time raises the number of devices a handler can process. The hollow rotating platform must accelerate, settle, and lock position fast. Any delay in settling adds straight to the index time. Direct-drive torque motors inside the hollow rotary actuator remove the gear backlash that would otherwise force a wait before the next test cycle. Thermal cycling adds another layer of difficulty to rotary table design. Tri-temperature test handlers expose the device under test to extreme heat or cold before each socket insertion. This temperature swing also reaches the rotating platform itself. A precision Motorized Indexing Rotary Table built with stable bearing preload resists thermal expansion. Otherwise, thermal drift would shift the angular reference point. Therefore, the socket alignment holds steady across the full temperature range, from sub-zero conditions through high-heat qualification testing. The hollow bore at the center of the rotary table also solves a wiring problem unique to test handlers. Vacuum lines hold each device in its carrier pocket, and they need a path through the rotation axis. Signal cables that carry test commands to embedded sensors need that same path. A hollow shaft rotary actuator routes both through its center bore. This routing eliminates the external cable wrap that would otherwise twist and fatigue with every rotation cycle. It also keeps the vacuum seal intact over millions of index cycles.

Case Study: Turret Upgrade in Malaysia

A semiconductor test facility in Malaysia upgraded its turret-style handlers with a Motorized Indexing Rotary Table rated for sub-arc-second repeatability. Before the upgrade, the facility tracked socket pin replacement after roughly 800,000 insertion cycles. Contact wear from misalignment drove this early replacement. After the upgrade, pin replacement intervals extended past 2.1 million cycles, based on maintenance logs the facility shared with its equipment supplier. The improved angular repeatability reduced lateral pin scrub at each insertion. Contact wear dropped as a direct result.

Function Map Across IC Test Handler Stations in Motorized Indexing Rotary Table

Station Function of Motorized Indexing Rotary Table

Positioning Priority

Pick from tray Indexes empty carrier into pickup position Repeatability Soak/thermal Holds device through temperature stabilization Thermal stability Test socket Aligns device contacts to socket pins Sub-micron accuracy Sort/output Rotates tested device to correct output bin Index speed Encoder feedback closes the loop on positioning accuracy for every rotary table generation. High-resolution absolute encoders report the turret's exact angular position back to the handler controller. This happens without a separate homing routine after each power cycle. Test handlers often run continuously across multiple shifts. Any unplanned homing sequence stalls the entire test queue, and every loaded device waits in place.

Specifying the Right Indexing Rotary Table