Happy’s Essential Skills: Computer-Aided Manufacturing, Part 2 - Automation Examples
In Part 1, I explored currently existing automation protocols and some new ones just coming on the market. Here, I will present some examples from my own projects.
Semiconductor Productivity Network at HP: PC-10[6]
Semiconductor fabs like to avoid writing custom software to fit all of the idiosyncrasies of individual processing systems. So HP developed PC-10 to handle IC process equipment by separating it into general classes. SECS II was a mandatory prerequisite of the equipment before an interface to PC-10 could be developed. (Figure 9 and Figure 10.)
Figure 9: Real-time monitoring of equipment status. (Source: Sematech Generic Equipment model)
HP's approach to interfacing was to survey a representative number of processing systems within a class to develop a generic model. A class is a group of equipment systems that operate similarly and perform the same general functions so that the communications requirements look the same to PC-10. The assumption is that each piece of equipment in an equipment class supports a subset of the SECS II data streams and functions that PC-10 supports for that class. HP also assumed that the order of the messages, which is not defined by SECS II, is generally the same for all equipment in that class. In the July, 1985 HP Journal article[6], the author reported:
To date they have encountered batch, metrology, serial, and material handling equipment, systems, such as diffusion furnaces, process wafers in large quantities (batches). The primary characteristic is that once a batch has started processing, no more wafers can be added until the process sequence has run to completion. PC-10 will download only one recipe to the batch station when the batch is tracked in and no other batches will be allowed in until the first batch is done.
Metrology systems are classified separately because they provide certain measurement data to PC-10. PC-10 supports SECS II stream 6 messages, which handle the transfer of measurement data to the host system for this class of equipment. Examples are line width, film thickness, and defect measuring devices. Wafers passing through these stations are not processed, but are merely measured to determine the effectiveness or accuracy of previous process steps.
Serial processing handles wafers one at a time. Wafers from one lot may be entered into the equipment for processing before the preceding lot has been completed. Photolithography wafer track systems are a prime example of serial equipment. PC-10, to ensure that the proper recipe is executed for each lot, must check to see if the recipe already executing is the proper recipe for the next lot. If not, it must download the new correct recipe at the proper time for beginning processing of the new lot.
Material handling requires an entirely different set of messages, since material handling systems are responsible only for transporting the wafers from one station to another. PC-10 instructs the material handling system to take a lot or a group of lots to a particular piece of equipment. Examples of material handling systems include robots or tracks used to move the wafers through the fabrication area. The challenge we face when we address a new class of equipment to develop our models is to perform an adequate survey of such equipment on the market and develop an accurate, yet general model of how these pieces of equipment operate.
Figure 10: PC-10 process control and process supervision including recipes’ downloading. (Source: Sematech Generic Equipment model)
Figures 10 and 11 are simple schematics of the CIM hierarchy in wafer fab using PC-10 as the equipment controller.
Computers Come to Plating[12]: Computers were first applied to PCB manufacturing at HP’s Palo Alto facility in 1974. Figure 12 shows the computer controlled plating system that included hoist (Figure 13) control, current control and monitoring for the plating tanks, chemical replenishment for the plating cells and multiple process sequence recipes (Cu, Sn/Ni, Sn & Au} that HP used for all its different 23,000 separate products.
Figure 11: Process recipe on PC-10 to be downloaded by SECS II and GEM. (Source: HP Journal, July 1985)
Figure 12: Automation diagram of the plating system used at HP’s Palo Alto, California facility. (Source: Metal Finishing Magazine[12])
Figure 13: One of the robot hoists is controlled by the computer system.
CIM environment for the Sunnyvale PCB factory[13]
The Sunnyvale, California PCB facility was built in 1981 and had even more factory automation than Palo Alto, California facility did. The many systems it had were:
- WIP tracking
- CNC for drilling
- Low-volume robot lamination
- Wastewater treatment process control
- AOI and Electrical Test
- Production scheduling
- Computerized plating and chemical control
- Laboratory automation of chemical analysis
- Inkjet individual board serialization for traceability
Figure 14 shows the overall CIM System Information Flow. This was the first implementation of HP’s automation strategy, “The Manufacturers Productivity Network.”
Figure 14: CIM information flow for the Sunnyvale PCB fabrication facility.
Figure 15 shows four of the automated systems controlled by the CIM network: a) Electroless copper and multilayer desmear line; b) Dual copper-nickel-gold/tin plating lines; c) Automatics chemical analysis, control and dosing; d) Robotic material handling in multilayer lamination.
Figure 15: CIM information network: a) Electroless copper and multilayer desmear line; b) Dual copper-nickel-gold/tin plating lines; c) Automatic chemical analysis, control and dosing; d) Robotic material handling in multilayer lamination.
References
- Industrie 4.0 Smart Manufacturing for the Future
- Introduction to Serial Communications, TalTech Instrumental Software Solutions.
- IEEE Standard Codes
- IEEE-488
- Message Automation & Protocol Simulation (MAPS™), GL Communications, Inc.
- “Semiconductor Productivity at HP,” HP Journal, July 1985.
- SEMI Standard E30, General Equipment Model.
- IPC Status of Standardization; IPC Committee Home Pages.
- Smart IoT Technology for Machine Condition Monitoring, Advantech B&B SMARTWORX
- Hermann, M., Pentek, T., Design Principles for Industrie 4.0 Scenarios, Working Paper No. 01/2015, technische universitat-Dortmund, 2015.
- Industry_4.0, Wikipedia.
- “Computerization comes to Plating,” Metal Finishing Magazine, May, 1978.
- MPN: Alive in Sunnyvale PCB; CIM brochure.
Happy Holden has worked in printed circuit technology since 1970 with Hewlett-Packard, NanYa/Westwood, Merix, Foxconn and Gentex. He is the co-editor, with Clyde Coombs, of the recently published Printed Circuit Handbook, 7th Ed. To contact Holden, click here.
