Automating Hazardous Gas Delivery
When a highly flammable, toxic and corrosive gas delivery system for semiconductor production tools became unreliable, Headway Technologies contracted with system integrator KCC Software for the needed upgrades. KCC Software’s experience and expertise led to the successful replacement of a failing automation system with a new automatic gas control (AGC) system.
Headway Technologies manufacturers memory and drive head products for the semiconductor industry at its Milpitas, California facility. It’s the largest independent recording head supplier to the hard disk drive industry, and it’s part of the TDK group. As in many semiconductor processes, Headway uses industrial gases extensively. In its facility, each single point gas supply is distributed to up to eight production tools through a valve-manifold box (VMB).
Due to the hazardous nature of the process gases, they are monitored constantly by the VMB during distribution through multiple legs to the production tools. Gas purge and maintenance functions are an important part of the process as well.
Reliable Purge and Supply of Gas
Most of the time, this AGV system is delivering gas while monitoring multiple pressure transducers and flow switches to check for proper pressure and flow. Leaks, low gas supply, valve failures and manual valve closure can be detected by falling or rising pressure. Gas pressure out-of-limit faults must be corrected immediately.
Before opening the pipe for maintenance such as valve replacement, the gas remaining must be carefully purged due to its flammable and/or toxic nature. Purging is an involved and long process, sometimes taking hours to evacuate all the gasses, and it’s also required after completion of maintenance to remove contaminants and refill the pipes with process gasses.
While much of the gas distribution could be controlled manually or semi-automatically, full automation provided by the AGC and the VMBs was deemed safer for purging gas.
In the Headway Technologies facility, seven VMBs were installed in clean rooms close to the production equipment. Reliable monitoring of pressures, flows and general alarm conditions were needed to ensure continuous operation of these critical gas delivery systems.
The original AutomationDirect DL205 WinPLC CPUs were becoming obsolete after many years of use, so when a series of large power spikes damaged some of the controllers, Headway Technologies chose to upgrade them. To perform this task, they contacted with KCC, the company that designed and programmed the original equipment.
Automation System Details
KCC Software’s previous experience with the AGC and VMB equipment led to its selection for this project. KCC has been a system integrator in Huntsville, Alabama for over 20 years, and has completed dozens of projects using AutomationDirect PLCs, working as an AutomationDirect SI Direct system integrator.
KCC Software’s review of the VMBs mechanical components found there was no need for replacement. However, it recommended the 12-year old PLC CPU and HMI be replaced. A new controller and HMI would simplify integration, and the new hardware would ensure long-term service and support.
A new AutomationDirect Do-more H2 Series Programmable Logic Controller CPU was retrofitted into the equipment. A big benefit of using this controller is that it works with the existing system’s AutomationDirect DirectLOGIC DL205 hardware. All the original I/O modules and wiring remained in place, facilitating a faster and simpler upgrade at a reduced cost.
KCC wrote the programs for the new AutomationDirect PLC and HMI to control the AGC. Functionally, the AGC includes five modes of operation including auto, manual, maintenance, configuration and setpoint. All modes are password protected and provide varying levels of access for operators, maintenance and engineering personnel.
While the process spends much of its time in auto as its primary operating mode, manual and maintenance modes provide the management tools required to maintain the VMB using purge and evacuation functions. As a wide variety of gases are used, KCC added significant configuration and setpoint functions for a fully adjustable system.
It’s a Gas
The new PLC and HMI were installed at Headway Technologies in the spring of 2016. The hardware was installed quickly—and software and application testing, followed by verification, took less than three days. The maintenance and equipment personnel at Headway helped KCC with system verification which resulted in a successful project with a quick startup.
Three AGC systems have been installed to date, and Headway Technologies is pleased with the results. The new hardware and software duplicated the best of the existing process, while adding more user-friendly operation and additional functions for control and management of the VMB processes.
Additional VMBs will be added in the future, and other upgrades, including new AutomationDirect controllers, are in the works at Headway. A notable project is the planned use of an existing AutomationDirect C-more HMI to send emails based on critical events or alarms in the process. These notifications will free operators from the task of watching the system during the long purge process.
For more information, please see the article Automation System Manages Critical Gas Distribution Process in the May 2017 issue of NASA Tech Briefs, authored by Scott Martin, owner of KCC Software.