What are these IPC standards stuff, anyhow?

Hello board,
I was reading another thread that mainly answered by precious member of this forum "House_Cat". Actually many aspects covered in that thread was new to me and I found myself in front of an unexplored world but most interesting was IPC standards. I visited the site www.ipc.org but quite frankly I did not understand anything useful. What is this? is it a universal standard like SI? I saw many big companies were members of these guys so it made me uncomfortably curious to find out who are they but they asked me to pay to see their standards! what a...! anyway, what these standards mean practically. e.g. do they recommend a specific clearance between high voltage tracks? is it really beneficial for me to use their standards? are these standards mandatory? should I follow them if I want to pass EC? Are there other parallel standards(hopefully free). especially is there a standard for passing EC?
Thank you very much

The IPC standards are a collection of standards taken from the major players in industry, put together so that there are at least some standards available.

This is mainly for the US market, although some other countries do also use them because they may not have thier own.

AFAIK they are not mandatory, however if you wish to sell in the US market it may be, or at least more benificial to conform to the relevent ones.

UKPCBL may be able to explain better.

They are copyright documents although there are some floating around the web for download.

As an example std, the IPC782 SMT PCB footprint standard - I used that for my SMT libraries and it improved manufactoring because there were less faults, solder balls etc. Now that it has been replaced by the IPC7532 std that should be even better.

www.pcblibraries can explain better about that, with the free footprint calculator too.

Other standards define what is good & what is not for PCB assembly, laminate fabrication etc.

yes they do also include track clearances.

As for parralell standards, there are British standards available for free viewing if you are a member of a british library.
but I do not think that they are as good as the IPC ones as the BS ones only seem to be about symbol shapes.

Thanks a lot cyberrat, I mostly interested about european markets and especially getting EC.
I remember I heard(or read?) somewhere that there are some legal obligations that should be followed in PCB designs across Europe. are you aware of such rules? are they in form of downloadable standards?for example I heard if a track carrying mains voltage have less than a specific clearance it will be considered illegal. of course I use some formulas to calculate such clearances but they are not in an official document. I'm interested in any document that is needed for PCB designers to be aware of if they want to get EC.
Thanks a lot.

PS: what about incompatibility of older parts with new standards? you said that IPC produces newer standards but older parts have been manufactured according to older standards so is it accurate if we say newer standards are good as long as one consumes parts that have been manufactured more recently.

There is a really good article in Circuits Assembly this month that talks about the history of the IPC and what it has done for the industry.

**broken link removed**

There are also UL standards.
It all depends upon what a country calls for and what the market in that country calls for.

IMO you need to investigate your market more to find out what standards they need your products to apply.

However, if you design your boards following the IPC, UL or BS standards then they should be better & more saleable than those products designed not using standards.

As for track distances, yes if you do not keep appropriate mains clearances then there can be problems with european directives such as the low voltage directive.

Then you have the EMC one.

Design is hampered by directives, all wanting to make the product safer (well they do really).