I would like to get a sense of the process yield rates that should be expected for COB processes. Apologies if this is a duplicate of previous discussions, but I could not find anything directly on this topic.

I understand that process yields are going to be affected by a LOT of variables. Also, I buy into the idea that there is no such thing as “good enough” and that continuous improvement should never stop. 

Having said that, I am really just looking for a very rough reference so that I can get a more objective evaluation of my bonding operation performance.

Some rough description of the process and products:

•	Pretty good productd volume: ranging from 300k annual to 1500k annual per product.
•	One or two die per PCBA.
•	Bonds per die fairly low: range between 12 wires and 20 wires per die.
•	All die 100% flying probe tested prior to sawing, with 100% visual inspection after sawing.

Our volumes are high enough and product life long enough that we can afford to invest in changes to the product to improve productivity and yield. 

My questions are along the lines of these: What sort of yield would make you think to yourself “Yeah, that’s not fantastic, but it’s not too bad either.”? What target would you be trying to shoot for?

Any questions or comments welcome.

Thanks,
Steve Hackney
Toronto, Canada