Prevention of illegal use of PCB Layout software?

[barry]

I see that this is not the only place Treez is going on about this.

A 1 man mission to get dumbed down instructions, even dumber than actually do exist.

This comment summed it up best (paraphrased): 'he's creating a solution in search of a problem'. QED

 

[treez]

I understand that you don't want dummy's guides produced for all the major PCB layout pakcages?
Supposing that they were payed for by a rich sponsor.
Do you still then object?

Supposing you want a junior apprentice to make a simple Test PCB (eg a load bank) etc.
Don't you think it would be helpful for him to have a dummy's guide?
Supposing he did it in a free one, say Eagle.....then suppose another technician uses diptrace, another KiCAD, another vutrax,etc etc
...none of them can modify each others schematic /pcb....do you think that's a problem?

Suppose someone can take a schematic to pcb in a major pcb package without problem because they have excellent IT skills, but supposing that they don't lay it out well , electrically, eg they make high power pulse current loops wide in area......do you think that's a problem?

Also, what percentage of people who use major cad packages do you think could identify say, the 'rectifier loop' and the 'power switch loop' in a switch mode power supply?

Also, do you believe that in some companies, the mechanical engineer uses the company's major pcb layout package, and doesn't even understand ohm's law?

 

[marce]

T5400...now that is interesting QFN vs TQFP.

I had to squeeze some fets onto a part of a small board once, so I had to use these little QFN type fets....the clearance between the pads and the inner, large thermal pad is incredibly small.
-As much as I trust modern technology of component placement machines, I can only think that some of the QFN's will slide about on the solder and short out.

It seems now that most of the fets and led driver ic's have the QFN style now.......sometimes you can get them in like TQFP, but they don't tend to have the inner heat-removal pad.

Making the footprint for the QFNs is very critical, and i'd say for that kind of package, the PCB Layout guy needs a second pair of eyes to check out the footprints just to make sure they are optimal.

I reckon even the engineering manager him/herself should occasionally open up the component library now and then and check out the QFN pad sizing and spacing...its that critical.
Now, who doesn't think that the engineering manager doesn't need a dummy's guide to allow him/herself to learn how to inspect the component libraries of a complex pcb layout software package?......................in my H.O., the engineering manager should do this literally "behind the pcb layout guy's back", so that he can really check that things like footprints are being done right.

IPC-7351

Regarding TQFP's one of the biggest sources of solder bridging during assembly often due to the lack of solder dams between pads due to the pad sizes and pitch.

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Thanks T5400, when you say stencil you mean the solder paste stencil?
Also, since you are in China, can you tell us which PCB Layout Software package that you use.
As far as I can see, the most successful Electronics design company in the world today is China, so youmust have some good ideas about PCB Layout too.

I hear that in China all the Electronics Companies are Government owned, which has definite advantages, because the government can get the various companies to pool their knowledge and skills and work toward the success of the Chinese Electronics industry altogether.
Since all the Chinese Electronics companys are closely Government controlled, is it true that the Government has instilled that only two different PCB Layout packages will be used?.......a simple one for simple pcbs, and amore complex one for the more complex stuff?
Can you say what are the pcb layout packages used in China? Can a Chinese company freely decide which pcb layout package to use, or must it seek Government advice?

As stated earlier, China specialises in manufacturing and assembly, a lot of design is done outside of China and sub contracted there.

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I understand that you don't want dummy's guides produced for all the major PCB layout pakcages?
Supposing that they were payed for by a rich sponsor.
Do you still then object?

Supposing you want a junior apprentice to make a simple Test PCB (eg a load bank) etc.
Don't you think it would be helpful for him to have a dummy's guide?
Supposing he did it in a free one, say Eagle.....then suppose another technician uses diptrace, another KiCAD, another vutrax,etc etc
...none of them can modify each others schematic /pcb....do you think that's a problem?

Suppose someone can take a schematic to pcb in a major pcb package without problem because they have excellent IT skills, but supposing that they don't lay it out well , electrically, eg they make high power pulse current loops wide in area......do you think that's a problem?

Also, what percentage of people who use major cad packages do you think could identify say, the 'rectifier loop' and the 'power switch loop' in a switch mode power supply?

Also, do you believe that in some companies, the mechanical engineer uses the company's major pcb layout package, and doesn't even understand ohm's law?

TRAINING, I believe in training people and continuous training.

Your views on the electronic design world are totally at odds with mine, you paint a very dark picture and do not seem to look at the socio9 economic factors that are also at play.

 

[treez]

Regarding TQFP's one of the biggest sources of solder bridging during assembly often due to the lack of solder dams between pads due to the pad sizes and pitch

..this sounds interesting, are you implying that solder bridging is more likely with TQFP than QFN?

 

[T5400]

Hi

it imply that anything fine pitch 0.5mm and down that have wrong pad design
may got to thin solder mask bethen pad , in that case pcb shop may remove it
or let it but so think that it broke ,then it will do solder bridge

that wly PCB designer need to work closely whit it PCB fab and assembly shop

 

[Mattylad]

Treez, what packages are you referring to that do not have basic learning documentation that can come with them?

Please let me know then I can prove to you that they do, I can show you a link to them.

The issue then will still be one about you not being able to read them.

I can really only speak for CADSTAR, however I know damned well that there ARE basic and technical documents available - including over 130+ videos for how to use it.

 

[T5400]

Hi Mat

even if i not agree whit Treez point of view ,from a outsider some document was harder to find or not very public
that may good to have some publick list of link and of course somewhere else that in that strange tread ..

but for a newbie that start it have many video on youtube that do the job very well and that was very easy to find

Best regard

 

[treez]

The person who I am investigating for doesn't want to single out any particular ones, as it would be unfair to them, when in truth, they are all just the same, bar eagle, though to be honest, eagle's own tutorials aren't as good as the ones created externally to eagle. then theirs the issue of forum support for problems........stuff like, "im trying to measure between two copper landmarks and it keeps snapping to the wrong landmark, how do I solve this in the xxx package".

 

[marce]

Again learn the tool you are using, PCB design is a complex problem, with all the requirements it has to satisfy.
I have had to do it as have many others, a good craftsman knows his tools and how to use them, this adage is the same for anyone who uses tools to create things, if the tools are to complex for someone to understand then my view is they are probably in the wrong job.

 

[treez]

I (and many others) don't have any problem whatsoever using Eagle Pro to lay out eg 4 layer boards with eg 2 SMPS on it, one 64 pin micro, and a load of analog control circuitry.

Sit us in front of a major cad package and give us a much more simple board to work on...and its far far harder.
many companies these days don't give staff the time to learn one of the big cad packages.
I went to one place where they thought two days was enough to learn the whole thing from scratch.

 

[ZASto]

treez, suppose that we could reverse the time flow and bring you back approx 20 years, give you today's Eagle, would you be able to lay a simple board (no 'net access for guides for dummieez)
You can not compare different PCB packages by only referencing how many "guides for dummieez" exists for the same.
Let me put it this way: I'm used to use P99SE, I'm using left hand on keyboard for shortcuts and right one caressing my mouse . Tried Eagle, some time ago, and did not like it's "way how the things are done", totally counterintuitive for my small grey cells.
Tried AD, too bulky for my 'putter with a lot of bells&whistles that are of no use to me, but, you know, Altium used to be known as Protel.

 

[Mattylad]

So its not the simple how to use it guide you want, you want the complicated info simplified.
Have they tried F1 ?

I dont think your going to get info like that unless you ask someone that knows how to use it.

As for making it public - I doubt that's going to happen too - these companies are in business to make money so will sell you the software and access to how to use it - not give it away.
Giving it away will not make its use any easier or topple governments, you'd need the software to be able to use the info - if you legitimately have the software then you should have access to the info.
However if you have a dodgy copy....

 

[treez]

Well I am not sure going back in time 20 years.

But when I bought Eagle Pro quite a long time ago, they (at cadsoft.usa) told me that it could be used to lay out computer motherboards.
However, they said it could only route one differential pair at a time, and only manually, not with the autorouter.
They also said it could not do multiple track (bus) routing.

So I was surprised they said it could be ok for computer motherboards, but they said it would be.

 

[marce]

..this sounds interesting, are you implying that solder bridging is more likely with TQFP than QFN?

I am not implying I am just putting down views from years of working closely with production departments and having millions of boards assembled over the years.
There are other problems with Quad flat packs, such as lead length from PCB to actual silicon, leads are very delicate and can bend causing dry joints ...

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Hi

it imply that anything fine pitch 0.5mm and down that have wrong pad design
may got to thin solder mask bethen pad , in that case pcb shop may remove it
or let it but so think that it broke ,then it will do solder bridge

that wly PCB designer need to work closely whit it PCB fab and assembly shop

IPC-7351 for component footprints...

Add this to your manufacturing instructions...
3.11 Solder Resist
Solder resist (solder mask) is required on both external faces of the printed board, it shall meet the qualification/conformance IPC-SM-840 class H. Coverage, cure and adhesion shall be as defined in paragraphs 3.8.1 to 3.8.3 of IPC-6012, except that no encroachment of solder resist is allowed on any surface mount or ball grid lands, and that ALL pad patterns have solder resist slivers between individual pads. The height of the solder resist should not cause any mounting problems for surface mount components.
Solder resist data is provided as per IPC-7351 standard, 1:1 with the land size, the manufacturer is to oversize these solder resist openings commensurate with their manufacturing procedures ensuring that ALL the above requirements are met, the amount of oversize to take into account the minimum track and gap dimensions as shown on the Printed Boards Master Drawing. Solder resist not related to a component pad is not to be enlarged.

 

[T5400]

Hi Mace

yup but low cost chinese fab dont care of IPC so most of time it just delete the solder mask bethen pin

bib did solder mask not fall in ipc 610 ? anyway i see many low cost shop that remove it even if good footprint was used
opening solder mask permit overcome Fad registration issue on mask and copper and most of time it open it so mutch
that it fall under minimum so it remove it or let it and mask break and go over pin ...

but agree that this was only on very cheap fab normally it not happen ..

 

[marce]

That why I use that instruction, and check the PCB's when they arrive, I have sent boards back before because of this round QFP pins. QFPs are also a pain to solder when HASL finish is used (this also increases the chances of bridging as you cant control the solder volume), it can cause the pins to bend up during placement and not soldering properly. A flat finish such as ENIG is required, this of course is mandatory for QFN packages and all small SMD components.

 

[T5400]

Hi i totally agree whit EING
many shop use for HASL cheap solder that contain nickel in the allow (Sn100C ,AS9930NC etc)
and this may pose issue when wix whit SAC305 and some type of flux

but that fall bit out of topic ,so back to endless and point less anything except eagle basing ;-)
or maby time to just close tread to he he since i may fall under x was better of Y rule to ..