Semiconductor front end automation took place decades ago. The sensitivity of the front end process was requiring it and the always equal form factor of the wafers was supporting it nicely with a standardized transport media, the FOUP (front opening universal pod). It provided a standardized interface for all material handling and processing equipment and the wafer handling is, in general, very reliable and jam free. Automation companies were therefore able to address all technical requirements of the flexible automated material handling between standalone equipment in the fab.
On the other hand the semiconductor back end has had to deal with all kinds of different package types and form factors, resulting in different transport media, such as bulk, tube, metal magazine, tray and reel. Even though SEMI has started to standardize this media, there are still many different form factors to consider. This has made it impossible to come up with a global material loading and unloading type for all equipment. It was therefore less costly to move backend into low labor countries to be able to manage and reduce the handling cost.
In addition the packages often have very loose tolerances making it very difficult to handle the devices reliably and jam free through the backend equipment once they were singulated. This leads to a test floor operation with many human machine interactions for clearing jams. But a test floor with frequent human and robotic interaction can lead to a less safe factory operation and may infringe on existing safety standards.
However, over the last 30 years two automation approaches were attempted in the backend. Only one was successful. Fifteen years ago strip test, and its integration in back end production lines seemed to be the Holy Grail solution to automate the test floor. While strip test is still around, the lines disappeared pretty quick again from the test floors with some exceptions. The integration of trim & form assembly equipment with test handlers and final packaging equipment was not successful because of the typically different speeds of the integrated pieces of equipment, causing the OEE to drop significantly compared to a flexible standalone operation.
The only successful backend automation ‘line’ that survived and found its justification is the turret handler. These handlers combine test and final packaging. These handlers are a fast and reliable solution for simple devices, and applications, when long setup times and limited parallelism and temperature test capability are acceptable. Turret handlers are the dominant solution for the discrete jelly bean test market.
Why is the backend getting serious in the move into automation? What boundary conditions changed? Who are the drivers?
With the new generation of collaborating robots there is the ability to get AGVs (autonomous guided vehicles) with robots onto the test floor in parallel with human operators and technicians without any safety concerns. This was not possible before and is now opening options that used to be prohibited due to safety concerns. The automated material handling of standalone gravity, pick & place, strip test and turret test handlers is becoming feasible and manageable.
Historically the transition of test floors into low labor countries used to be one of the answers to manage and reduce the backend cost. However, these low labor countries are now getting into significant cost pressure themselves. And European semiconductor companies, that want to keep backend operations in Europe, are forced to get even more efficient and go for the next evolutionary automation step to reduce the cost of the equipment idle times during material exchange. Because of this effect, Europe has been at the forefront of factory automation efforts with its so called ‘Industry 4.0’.
Singapore has a different reason for embracing factory automation. One of the first low cost manufacturing bases in Asia is now quite expensive with regards to operational costs. In addition it has a people problem as it cannot source enough production workers. Singapore has limited living space, and with the country’s economic and industrial evolution, more high skilled jobs are required putting a squeezing the ability of production workers being able to afford to live in the country. The Singapore government therefore is funding development projects for factory automation and is subsidizing companies’ automation projects.
With these changed boundary conditions, and the mentioned driving factors, the first automation implementation projects began in Europe, Singapore and Korea. Once they get effective in HVM, it is expected, that the cost pressure will force its implementation in the lower cost countries. The automation race is on.
Please contact us if you are interested, how we prepared our handling equipment for test floor automation.