Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


SPC for SMT

#23697

SPC for SMT | 6 March, 2003

Mike,

What is the most common method for monitoring and calculating machine capability for:

- Reflow oven, I currently run a carrier monthly to monitor its temperature profile and would like to simplify the process.

- P&P machines: We don't have a CMM and was told that our AOI can't output quantitative placement result.

- Wave soldering: We run carrier on a daily basis but it doesn't capture all critical machine parameters.

Rgds, Peter

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#23703

SPC for SMT | 7 March, 2003

Hello Peter, In reflow, running a profile and collecting thermal data does not necessarily make it easy to calculate and determine machine capability. On the contrary to your desires of simplifying the process, determining machine capability on an oven is going to be a little more difficult based on the amount of time it will take to complete an effective test. We are in development and looking for a company to test our methods. If you are interested please let me know. Details and approximate time needed for the process: thermal cycle a machine a number of times (from cooled to state to full peak reflow temps) and run a profile to collect data on each run. Each time, the data is uploaded to our statistical software for computation of standard deviation, mean values and other statistical parameters. One critical attribute that is measured each time is the machines ability to maintain the same peak reflow temperature for each of the cycles. Others are considered also. The approximate time now is 4-6 hours to complete a full test. I know this doesn't sound easier or quicker but it is a proper statistical method to accurately determine machine capability on ovens. For pick & place equipment, you were correctly told that your AOI cannot provide the output you want. Many manufacturers are touting their ability to measure machine capability with their AOI systems but in fact, their systems are not designed to accurately measure capability on production equipment. As you say, you don't have a CMM, well that is one method used to collect machine capability data on equipment but the procedures are arduous, expensive and time consuming as I've described in other related threads. Another method is using IPC-9850 but that also requires a CMM and is subject to interpretive risks as well. The solution for all of your SMT equipment is an independent and objective test method that measures machine and process capability. Our CmController system, offered as a product and service, is a 3rd party method used for accurately and quickly determining statistical performance on printers, dispensers, placement systems and others related to the electronics assembly process. In order to assess equipment performance using a system like this, you'll need to know the quality performance specification on your equipment. If you don't know this, the manufacturers should be able to easily provide for you. Only then can we measure the actual performance of the equipment against it's specification and determine it's Cp and Cpk performance capability. Based on our experience with P&P machines, some fine pitch machines are measured and optimized on a monthly basis to reduce downtime from maintenance and increase machine efficiency and availability. Chip shooters have been regularly measured every 6 months to maintain quality in a preventive maintenance program. There is too much to describe here, so if you have issues with any equipment, it is very likely we can help you diagnose and recommend fixes for the issues. For wave soldering, there may be a different system to use that captures more attribute data but the process is going to be similar to that of the reflow process I described earlier. We have not done any development work on wave machines for measuring capability but it is in our solutions roadmap. Let me know if you require additional assistance. Thanks!

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Solder Paste Inspection

Essemtec Fox Compact Automatic Pick and Place