Some people are afraid of spiders or snakes and I’m afraid of those too, but one of my worst fears is being audited. Now it’s time to start getting organized again and collect on all of my organization last year to make reviewing my notes and preparing for taxes easy. But, wait: my drawer full of notes and important receipts is also full of assorted shopping lists, grocery receipts, home repair goals, and that list I wrote in February for a workout routine that I stuck to for three days. I have a formal bookkeeping process, but, sometimes, I worry that it’s not enough. I wish I knew what the IRS was looking out for in their reviews process.
On the other hand, being the auditor isn’t just picking daisies. Especially if you’re auditing your manufacturing process for your PCB manufacturer, there are hordes of things to keep track of and pay attention to. While small batches of boards or simple PCBs with large tolerances probably don’t justify the time and travel for a full review, when you’re designing high density PCBs or large volumes of them, a thorough review should definitely be within your considerations.
Since the manufacturing facility may contribute to defects, it’s a good idea to audit your manufacturer’s facilities and practices. When you visit, you should be prepared with a list of items you want to review, like my checklist of tax forms and documentation. Everything from the equipment, the environmental controls, and the handling procedures should be considered. It may seem like a lot, but if you’re going to the effort to visit a manufacturing facility, especially if it’s overseas, it will be better to get it all done at once.
PCB Manufacturing Paperwork and Documentation Reviews
One of the first steps to any review will be looking at the available documentation. This can range from questions such as if temperatures and ramp times are recorded each the time the solder reflow oven is used if issues with etching are recorded, and how different products are tracked and kept separate during manufacturing. Having an understanding of your manufacturer’s documentation process will allow you to know what kind of information you’ll want from them, and what you’ll be able to have ready access to.
Just as important to understanding their documentation process, your manufacturer’s design security is incredibly valuable too. Horror stories like manufacturers using your design to start producing counterfeit versions themselves, or having unsecured computers where your proprietary designs could be easily accessed by unauthorized entities are as much a part of your review of your manufacturer’s process. Even if it seems redundant or insulting, it’s significantly better to ask the specific questions now instead of seeing a competitor learning your trade secrets.
You should verify security procedures during your audit.
What to Look for in Manufacturer Handling Processes
When you get into checking the manufacturing facilities, you’ll be looking into how the manufacturer handles the materials and the environment. Here are some of the key methods to check in your handling reviews:
Process Controls: Make sure that everyone who enters the area is wearing proper protection. That should include hair nets to keep static discharge from building up, as well as keeping hair off the boards in case of shorts. People should also be wearing wrist, and possibly shoe straps that are plugged into the ground at each workstation.
Environmental Controls: Along with process controls, you want to see good environmental controls. Contamination is a huge concern, and a dirty manufacturing environment will be almost impossible to compensate for. There shouldn’t be dust collecting on any equipment. Any processes that produce dust, like CNC milling, should be separated from the rest of the production line and cleaned regularly. Chemical processes should be performed under hoods or appropriate ventilation. Operator contamination sources, like oil from your skin, hair, or clothing, should be minimized by gloves, goggles, hairnets, or other PPE.
ESD Protection: One of the largest concerns for your PCB design is ESD protection. Having environmental protections for ESD during manufacturing will keep components and boards from suffering discharge damage. As much as I’ve harped on paperwork, ESD areas shouldn’t have any loose paper or packaging materials around that could get pushed around and generate a static charge.
Packaging: Always ask to see the packaging that gets used. Make sure that it meets your requirements for the product their currently packing, and that they are familiar with the type of packaging that your product will need.
As a final step, check how the materials and products are actually unpacked and packed to make sure the handling processes are consistent throughout the production process. Consistency and manufacturing safety is vital to the overall health of your manufacturing process.
Check if everyone in ESD safe areas is wearing the proper protections.
Optimize Your Manufacturing Process by Knowing Capabilities
Your first and main concern with a manufacturer’s audit would most likely be the actual production capabilities of your manufacturer; skipping over their review would be like itemizing your deductions when you have no income to report: an awful lot of work to miss the main event. Here is a list of things to consider:
- Go into your audit with a list of the facility’s production capabilities.
- Verify that they actually have every tool you think you’d be using. Ask what the purpose is when you aren’t sure, because they may have capabilities you didn’t know you could utilize.
- Ask to walk through the specific manufacturing path for your proposed products, and find out if they have any recommendations.
- Find out how old the tools are, how they get calibrated, and how often they are inspected.
- Ask about the performance of the tools and how it’s tracked. For example, when solder mask is applied, what’s the tolerance? How much variability do they see in a single mask, and across an entire manufacturing batch?
- Some manufacturers may also utilize off-site processing. Find out what, if anything, is processed elsewhere, and make sure you are comfortable with the details if you can’t visit it yourself.
The most enlightening parts of a manufacturer audit might be in finding out that a manufacturer can produce one of your designs in a cheaper and more effective way than you had previously anticipated. Being able to know confidently what your manufacturer is capable of will give you a clearer gauge of the success of manufacturing any of the potential designs you come up with.
Unlike an IRS audit, manufacturing reviews should be informative and helpful for everyone involved. It’s an opportunity to learn more about the production line, and how to improve your designs.
After you learn what your manufacturer’s capabilities are, you can use those guidelines to help improve your PCB design process with assistance from your CAD system. For easy application of manufacturer capabilities to PCB design software, consider using smart layout tools such as those found within Altium’s CircuitStudio.
If you’d like to learn more about how to apply knowledge about your manufacturer to your PCB designs, consider talking to an expert at Altium today.