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Design Aspects in PCB Design

Abdalrahman_Kamal , 11-03-2022, 02:29 AM
I was asked to help in reviewing an already done PCB for a product in my company.
What are the aspects I should keep in mind when reviewing a PCB or when editing this PCB?
For example, I know there has to be a review for availability of the ICs as there is a shortage right now.
Also, there has to be a review for compliance, like grounding and EMI filtering/shielding.
What about review for design for manufacturability, design for assembly, design for testing?

I am a junior here and this is my first job, so I hope I provided enough information.
Thank you in advance.​
qdrives , 11-03-2022, 05:21 PM
If you use Altium, use active bom to see availability of the components and, more importantly, the lifecycle. If not:
- Let the contractor tell you.
- A lot of manual work.

Design review "already done PCB": schematic? Layout? Production quality issues? In other words: is the design finished and needs review or has production already been done and now there are issues?
There are many aspects of a review and most of the ability to detect issues beforehand come from years of experience (i.e. failing, and asking questions).
Critical points heavily depend on the type of product/design:
- Does it have high speed?
- High power?
- High voltage?
- What are the safety requirements?
- Does it need to be low cost?
- High reliability?
- RF, medical, military or other highly regulated product?
But what is high?

As it is your first job:
1) Would you have designed (part of) the circuit in a similar way? If not, ask then why they did so. That way you learn a new approach and they may detect an error. Never be afraid to ask. If they are not willing or capable to explain it, then that is an indication that there may be an error in (that part of) the design.
1a) If you do not know how you would have designed a particular circuit then treat it as if they have used another approach then you did - so ask then to explain it.

2) Read the applicable standards and regulations (globally, or scan for interesting section). Check if the design adheres to those rules.

3) Learn, learn, learn. Yes there are plenty of videos, blogs and other sources of information. However, there are also many flaws in these sources, so do not consider them correct, but as helpers pointing to possible problems in the design.
Abdalrahman_Kamal , 11-06-2022, 01:26 AM
Hello again, thank you for your response.

I meant that the schematic, PCB layout and production have already been done, now there are issues that we need to address by reviewing the schematic and then the PCB layout.
The product is a consumer electronics product, and we need to pass the CE and FCC ratings.
- No high speed.
- No high power. (Pmax = ~15W)
- No high voltage. (Vmax = 13.5V)
- Safety requirements ==> ESD protection is the only one *as far as I know*
- Low cost is not really an issue much.
- High reliability is a must in our case.
- Consumer electronics product, not RF, not medical, not military, not HIGHLY regulated, but moderate regulated.
And yes, what is high?
Basically, we just want cheap, working, and pass CE & FCC tests.
We already have a starting point, so we can phrase my question into, how to check for design mistakes?

As its my first job:
1) Great approach, I will do so.
2) Will do that with CE & FCC tests.
3) Great advice.

Thank you so much for your time and consideration.
qdrives , 11-06-2022, 12:32 PM
So passing CE and FCC tests -- EMC / EMI.
Robert made some good videos with Ming ... Check them out.
Step by step explaining, debugging and fixing EMC immunity issue. Thank you very much Min ZhangLinks:- Min's Company: https://mach1design.co.uk/- PDF present...

Troubleshooting EMC problem can be done directly in your lab before going into an EMC test house. Practical example in this video - fixing Radiated Emission ...

Answering the questions about EMC that HW engineers often ask when they are designing boards. About EMC and simulators, heatsinks, shielding, filtering, moun...

I wish, they taught me this at university ... Thank you very much Arturo MedianoLinks:- Arturo's LinkedIn: https://www.linkedin.com/in/amediano/- The previou...

Thank you very much to Min for very nice practical examples to show how to improve EMC results ( Conducted Emission ) of a switching power supply.Sign up for...

Do you know what I changed to improve the signals in the picture? What do you think?------------------------------------------------------Would you like to s...

Sometimes the solution can be very simple and cheap - like adding a resistor or capacitor.

Another thing to point out is that the "tests" are actually a whole series of tests. Question is which one are failing:
- Conducted emission
- Radiated emission
- Conducted immunity
- Radiated immunity

Wideband or narrowband noise?
What frequencies?
robertferanec , 11-12-2022, 02:45 AM
That is a very hard job they gave to a junior engineer. My recommendations: learn, learn, learn, study, watch videos, talk to people, test. That is what you are already doing and @qdrives recommendations will help you.

You can also watch my videos with Rick Hartley and Eric Bogatin - these can help you better understand PCB Layout:
- https://www.youtube.com/c/RobertFera...eric%20bogatin
- https://www.youtube.com/c/RobertFera...rick%20hartley
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