I think Alexis was right to bring up the subject and I think it shows that most of us understand the problem and critical nature of the design requirements being spelled out in such a way as to not 'get it wrong' or inconsistent from one vendor to another. The science that goes into the design needs to be repeatable and consistent from one vendor to another and you, the designer, control this with the appropriate notes and details on the fab drawing.
On the other hand, if it is not a critical feature, please don't tie the board vendor's hands.... Give them the allowable freedom to change things that ARE NOT CRITICAL that favor their processes. (The question is... Is it critical in this case?)
Let's say that the designer on this board went to a seminar and saw a demonstration that defined the board stack up in great detail much in the manner that this board is done, and he/she decided to use a similar tight specific definition on all their boards regardless of the need to do so.... because it looked cool and impressive and made everyone think they knew what they were doing. The board vendor has no way to know if the designer specified the layering structure and types of materials and thickness requirements unnecessarily or not. They have to assume that you know what you are doing and that they may not deviate from it if they want your continued good business. Most boards do not need this type of treatment. Many RF applications DO NEED this kind of detail.
Perhaps this board MAY NOT NEED to be defined in the fashion it is and COULD be altered without any undue harm to the layout and assembly. We just don't know that without more information, but it's interesting to see the other comments and assumptions. I did not see anything in his original question that stated that the boards were already MADE. Perhaps they are in the shop preparing to make them. As I would expect the shop to do, they should call the designer with a question before taking any action.... And indeed that seems to be the case. To lambaste the guy or shop is to jump to conclusions... let him explain it more before calling him "dumb". That's just rude JaMi.
The intent here is to learn from each other and we do not know it all. None of us 'Know it all'. But we can fill in the gaps for each other and collectively we are more than the individual could ever hope to be. Let's use the forum to HELP each other not embarrass or ridicule.
Best regards,
Bill Brooks
-----Original Message-----
From: Tom Garman
[mailto:[log in to unmask]]
Sent: Monday, June
09, 2003 8:05 AM
To:
[log in to unmask]
Subject: Re: [DC] Core
thickness/emissions
Jami;
Alexis is competent enough to ask the right questions. Most of the people I have dealt with consider the other person to be competent until proven otherwise. From your posting I can see that you have not had the same experience. I have worked in situations where I had to prove my competence. I did not enjoy those jobs very much. Most board designers do not have advanced degrees in electrical engineering nor are they clairvoyant. In my viewpoint it is a waste of an engineer's time to be laying out boards. The engineer should be reviewing the layout but unless he is at the low end of the salary scale it is not cost effective for him to do layout.
PS I don't need to brag, I have witnesses.
-----Original Message-----
From: DesignerCouncil
[mailto:[log in to unmask]] On
Behalf Of JaMi Smith
Sent: Saturday, June
07, 2003 3:00 AM
To:
[log in to unmask]
Subject: Re: [DC] Core
thickness/emissions
Eric,
Unfortunately, it is not a joke.
I was just about to say that you obviously do not have any concept of what emissions testing is all about, either practically or legally, but then I looked at your email address and realized that you really do understand what is going on here, and appear to just be making light of it.
It is not just a question of simply radiating interfering signals when you are dealing with a cell phone company that makes an RF Transmitter that people hold up to their heads.
It also appears that you may have never spent long hours in emissions testing, trying to qualify a design, only to have to redesign it and requalify it after you have made a large production run that need to be scrapped, just because of some stupid idiot like the guy at the board house in this particular case, who probably just didn't have the right material in stock, or worse yet, had some extra material he just wanted to get rid of. This guy really does need to be called on the carpet.
I don't want this idiot making any boards for me, and I really don't think that you want him making any boards for you.
I want to know just who he is and who he works for, so that I do not make the mistake of sending him any business.
This kind of incompetence is a problem in our industry, and we will never correct it by ignoring it or sugar coating it.
Yes, incompetence is the correct word.
I am sorry if I am calling a spade a spade.
Why am I making an issue out of this? Because the average designer does not know what a monumental blunder something like this is.
This is important, and it is important that anyone who is out there designing boards knows that it is important, even if he does not totally understand it.
That's why it should not be sugar coated.
That's why I am being so polite.
I am sorry if you are offended, but once again, this is not a joke.
JaMi
* * * * * * * * * *
----- Original Message -----
From: [log in to unmask]">Eric Bonatti
Sent: Friday, June 06, 2003 4:53 PM
Subject: Re: [DC] Core thickness/emissions
Oh, come on JaMi, don't sugar-coat it. Tell us like you really feel.
Eric
----- Original Message -----
From: [log in to unmask]">JaMi Smith
Sent: Friday, 06 June 2003 19:26
Subject: Re: [DC] Core thickness/emissions
The quick answer is: Yes! Absolutely! Unquestionably!
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