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 Post subject: What makes a... PCB
PostPosted: Sat Jul 01, 2017 12:03 am 

Joined: Tue Feb 03, 2015 6:57 pm
Posts: 3584
Location: Low DOS
I'm going to slowly plow through a series of threads about the bottom line info (from a scrap point of view rather than the tech pov) on what things are and why they go that way.
Here in my second post following this I'll start with something everyone knows here: the printed circuit board. Or PCB. But as you'll see I'll dig a little deeper, in every sense, as to why a 1974 pcb goes as telco with minimal population and a metal socket board generally is near or below peripheral rate.
Why is fingerless so ram telco?
What makes cell phone and hard drive boards so expensive. Did you know that there were GLASS boards? What about Formica and wood?
What's the difference between two-ply and double layer?
What's a sandwich board?
Are gold and silver boards really gold and silver and how can you tell a gold sandwich board with real 22kt gold layers from a fancy gold flashed board?
This is my general premise here.
Starting with:

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 Post subject: Re: What makes a... PCB
PostPosted: Sat Jul 01, 2017 12:03 am 

Joined: Tue Feb 03, 2015 6:57 pm
Posts: 3584
Location: Low DOS
The PCB.
We all know what a PCB is but few here know all the PCBs.
I'll start right off with a list from most common to least of various designs.

Polymer (paper glass wood plastic, 99% of modern computer boards)
Plastic
Wood
Glass
Hematite
Silver
Platinum
Other metal base/alloys
Stone
Paper

Layers #
1
2
5
4
3
More

Layer materials
Copper
Nickel
Gold
Silver
Palladium
Rhodium
Other

A polymer board is made up of multiple materials. Though as of late most are multiple plastics and paper byproducts for most of the 90s and even into the 2000s a measurable amount of non-paper wood composite was used.
Today paper byproduct replaces wood scrap.

Totally plastic. Anything in a consumer product that gets really hot. Video cards are the prime example but many M2 cards and most ram is plastic if not glass.

Wood composites and wood plastic were the norm from the 40s through the 90s and make up the vast majority of today's low end boards still. They're technically paper rather than than wood but who's really keeping track.

Glass
High energy transfer and discharge boards.
I'll be honest here. 99% of the glass boards I've come across are from VCR, BetaMax/BETACord/BETAChord decks and analogue professional cameras.
Lots of older TVs and many server/gamer power supplies also included glass boards as do microwaves. Anywhere you find obscene voltage and minute amperage.

Hematite
Industrial equipment meant for extreme environments. E.g. Deserts and the artic.

Silver. Photography equipment

Platinum boards are used by NASA, USAF, and X-Space

Aluminium boards are common in servers for both the backplane and the CPU boards. Server memory backplanes are commonly nickel
Steel boards are used in military and defence computers.

Stone (nickel lime) boards are actually made from pressed unrefined metallic stone. They're found in custom servers for high altitudes. Again here the 99! 99% of the ones I've seen have come from IndoChinese boarder countries.

Finally paper. Paper boards are found everywhere and are absolutely junk. 0 value. You're going to decrease your dirty steel shred payouts by including this crap. 100% come from China and Israel. Afaik. Used in clocks, radios, CD players, headphones.


What is ply and what is layer. And a sandwich?

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-- my grades are my own and do not represent an offer from boardsort, nor are they guaranteed. Please keep that in mind.


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 Post subject: Re: What makes a... PCB
PostPosted: Sat Jul 08, 2017 2:52 pm 

Joined: Tue Feb 03, 2015 6:57 pm
Posts: 3584
Location: Low DOS
Plys, layers, flashing, sandwich? Yes sounds like a great delay sandwich.
Basic note:
The vast majority of electronic boards have atleast one metallic layer. This being almost any board that uses through hole define (THM, THD, PGA). The sole exception is rear trace boards.ill Ignore these for now.

Boards are made with two outer layers and a single metal layer in between with a lamination holding it all together. Or in less expensive boards the pcb will be moulded around a small piece of metal taking up minimal internal space. Various etches holes dimples and removed valleys control electrical use. Along with the control components .
Most boards have a single layer and the most common metals are copper and nickel. Motherboards and video cards are usually three. And here is where sandwich comes in.
Server equipment, high grade video cards, cell phones: and the like. Often use 4 or more layers of, normally, gold layers. Much of this falling into telco class or better despite the large size and reduced component occupation. A 7 layer server board has more gold than many CPUs by volume. Micro tablets (phablets) like the galaxy note series, the Mono Space, the Galaxy mega, all go as cell class due to the gold content plus population. As do TI-8x TI-9x and N-series calculators. For their 4 layers of platinum and layer of gold. N64 and Jaguar cartridges go as telco for their 5 gold layers and gold edge connector. Many Atari 7200 carts get telco for the nickel edge connector 3 silver layers and soldered gold pin rom .
This should all help in understanding the class benders.
When you've got a sandwich board with copper layers it's still in its basic class. If it's grey/silver in colour there's a chance for an upgrade depending on the layers material and if it's a gold sandwich we're going up!

Copper and nickel are universal. Gold is used where fault tolerance is not practical and it must work at all times. Where fault levelling is not possible or practical. Silver matchs gold's application for less money, slightly sacrificing quality. Palladium is used in very small boards due to its small atomic spacing in finished form. (Don't ask that's chemistry and out of my league). Rhodium is used where environmental tarnishing is an issue for palladium.

Any questions on what materials go where I can try to help. But when you get into the why's I'm not as well versed in chemistry. So I'll do my best to google it properly for you.

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-- my grades are my own and do not represent an offer from boardsort, nor are they guaranteed. Please keep that in mind.


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 Post subject: Re: What makes a... PCB
PostPosted: Sat Jul 08, 2017 3:05 pm 

Joined: Tue Feb 03, 2015 6:57 pm
Posts: 3584
Location: Low DOS
Flashing. Flashing looks pretty. Flashing has a legitimate electrical use. Flashing is generally not considered in value.
Flashing is nothing more than electronic paint. It's the electrical equivalent of a layer of dust, but not as thick. If you scratched the gold flashing off 100 USR modems and properly fully refund it you'd get a few dollars for your troubles. It's so thin wou can't weigh it even on a grain scale for most peripheral cards.
Flashing adds pennies, at most, not dollars, to the value. Boardsort doesn't buy them for anything extra.

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-- my grades are my own and do not represent an offer from boardsort, nor are they guaranteed. Please keep that in mind.


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