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Control System using LabVIEW & cRIO for Hotbar Bonder in X-ray Sensors

Cyth Custom soldering fixture
Custom soldering fixture.

The Challenge

A manufacturer of custom soldering fixtures approached us with the need for a system to control independently moving hot bars used to solder LCD screens.

The Solution

Using the NI CompactRIO and LabVIEW software platforms we designed and built a control system capable of user-programmable motion in 8 axes alongside PID loops for temperature and force to provide our customer with the complex controls required for machine functionality.

The Cyth Process

  • The Hotbar Bonder is a fixture for the custom soldering of LCD screens.

  • Cyth’s engineering team designed and installed the fixture’s controls cabinet featuring a CompactRIO 8-slot chassis, and 4-slot expansion chassis.

  • The fixture’s two hotbar soldering irons move independently and are controlled using LabVIEW stepper motor control architectures.

  • The hotbars soldered 200+ pins simultaneously. using programmatically applied PID loops for heat & force measurements.

Left: NI cRIO-9038 8 slot chassis featured in the Hotbar fixture control system, Right: NI 9152 C Series Motor Drive Interface Module

Order of Operations

  • An operator loads the LCD bed onto a trolley that moves along a fixed track.

  • A camera instructs the operator as to the LCD bed’s alignment.

  • The operator inputs the soldering instructions and recipe into a LabVIEW user interface, which auto-calculates the fixture’s actions required to solder the LCD’s entire area.

Control System Features

  • Soldering tips contain zero-crossing solid state relays that apply 120V, controlled by the cRIO.

  • Solid state relay pulse with modulate (PWM) at 30% duty cycle within a closed loop temperature PID to hit the required temperatures for the soldering recipes, with a thermocouple to measure temperature readings.

  • Recipe editing within LabVIEW user interface (UI), enabling the operator to sequence where the hotbar moves in x & y-axis positioning, as well as setting the required force and heat, and looping the instructions for the bed’s entirety

  • The CompactRIO contains eight Third Party Stepper Drives – one for each axis of movement.

  • The NI 9152 C Series Motor Drive Interface Module instructs the stepper motor drive when to move and the drive amplifies the voltage to the motor.

  • It contains a15-pinn DSUB for the drive step command signals, and a 20 pin MDR connector provides incremental encoder feedback inputs.

  • Multiple 24V power supplies to ensure the required fixture current.

  • Industrial PC for an operating system that displays the camera feed in real-time, for operator viewing during alignment & printing function.

  • Relays to ensure high voltage & high current safety.

Delivering the Outcome

The Cyth control system has enabled our customer to bring their hotbar bonder to market. The NI CompactRIO and LabVIEW software platform enable us to provide deterministic controls in a real-time system that consistently executes tasks in a specific time constraint. The user programmability of the fixture’s software interface also greatly enables the end customer. From development to deployment, Cyth has assisted our customer in a turnkey controls system for LCD hotbar bonding.


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