PCBCart - anyone knows it ?

[KatieandDad]

I bought a cheap Samsung Laser Printer £30 GBP. All you need is some thin inkjet photopaper and Voila. Boards for pennies.

Initial cost might seem high but once you've bought the printer you can make boards for less than £1 GBP / 0.1m^2

I only use the laser for PCBs as its far cheaper to use the inkjet for normal printing, especially if you refill the cartridges with bulk ink.

[cocolino]

Originally Posted by marce

Why have a thick silver finish?? you cant realy solder through it.
For SMD and DIY ENIG will give best shelf life, also acceptable for PTH.
For through hole designs lead free HASL will do, and is probably the cheepest, not reccomended for SMD boards though.
OSP again for DIY avoid, limited shelf life, storage problems, same with immersion TIN and immersion silver, shelf life is limited.
Of all the finishes I use and prefer ENIG, good shelf life, good solderbility and nice flat pads for SMD.

Hi marce,
I have a couple of questions:

I know what HASL is but could You please explain what`s "ENIG"?
Why would HASL be not recommended for SMD boards? Because of possibly not so even surface?
"immersion TIN": does this refer to a chemical (opposed to physical as HASL) process to apply tin?

[peranders]

Electroless nickel immersion gold

Electroless nickel immersion gold - Wikipedia, the free encyclopedia

HASL is OK for big stuff but the surface can be a bit uneven for fine pitch parts.

[cocolino]

Originally Posted by peranders

Electroless nickel immersion gold

Electroless nickel immersion gold - Wikipedia, the free encyclopedia

HASL is OK for big stuff but the surface can be a bit uneven for fine pitch parts.

Ahh, got it, thank You!

[marce]

As Per-Anders has stated, HASL produces a convex meniscus when applied, this can cause all sorts of problems with SMD components:
QFP (quad falt packs) quite often have a pitch of 0.5mm, the legs are that delicate that during placement they can bend up, causing a dry joint, or even an unsoldered leg. This is made worse as quite often when a pin is probed it makes contact confusing the engineer.
Amount of solder on the pad. For commercial PCB assembly the amount of solder on a SMD pad is tightly controlled by the thickness of the solder paste screen, the size of the appert and the size of the balls (solder balls), the solder paste also contains the flux, this is the required amount for the solder in the paste, and dosn't cater for the extra solder from the HASL process. Result possible dry joints, solder dose not flow well (especially with lead free solder) resulting in sub standard joints. Another possible defect is the cahnce of smaller chip components floating during reflow, causing them to twist oun the footprint, or in the worse case tombstone.
I wont bore you about intermetalics, but during the soldering process various intermetalic layers are formed, varying on the surface finish, the finish on the pin and the solder used. When tin lead solder was the norm, this wasn't as critical as nearly everything had the same plating, now there is a whole host of finishes on components, the board, and the choice of solders I keep a record of every part in my CAD libraries termination plating, as we use tin/lead solder process with lead free parts, a big pain.
ENIG from my experience and experimenting over the years with all the other finishes is the best to use, for shelf life, ease of storage, solderability etc. Though due to the price of d a finish morer often associated with gold pad bonding is becomeing popular ENIPIG (they use a layer of palladium, so they can use less gold), I haven't tied it yet but have read numerous IPC reports on its performance, the jury is still out though.
By the way Per-Anders the PCBlibaries are coming back to life.
http://www.pcblibraries.com

[peranders]

Originally Posted by djQUAN

I've dealt with PCB cart for 3 orders now. all are very good, no problems so far although lately I think their price has increased a bit.

re: papcb.com - a quick look in their site and you see the "pcb direct sale from china" and "start quote" picture is the same as pcb cart. I can't see any 'about us' links so I'm not sure if they're related or that papcb.com webmaster isn't that creative in making their own layout so they did print screen or something.

I'm think this is a case of copying. It is also worth noticing that both companies say nothing about their real name or address although I know facts about pcbcart.com

Not much life in pcblibraries.com
EDIT: http://www.pcblibraries.com/forum works better

[marce]

Woops, all the old threads are gone, despite Mentors initial idea to archive them for reference.