PCB surface finishes

Thread Starter

engr_david_ee

Joined Mar 10, 2023
204
I just came to know that we need to tell PCB manufacturer about the surface finish which we don't define or include in the PCB layout in the design tools. What are these PCB surface finishes ? There are options for example, ENIG, ENEPIG, Leadfree HASL etc. Do they have any thing to do with signal and power integrity ? Is these finishes works only or applies only at top and bottom of the PCB ?
 

WBahn

Joined Mar 31, 2012
30,303
Probably the best source for answering these questions is to contact a PCB manufacturer and have a discussion with them. You may not find a willing ear at the first place you contact, but if won't take long before you find someone willing to discuss it at whatever depth you desire -- remember, they are in the business of providing these services to customers, so it is in their interests to educate their customers (and potential customers) about the services they provide.
 

Ian0

Joined Aug 7, 2020
10,277
I just came to know that we need to tell PCB manufacturer about the surface finish which we don't define or include in the PCB layout in the design tools. What are these PCB surface finishes ? There are options for example, ENIG, ENEPIG, Leadfree HASL etc. Do they have any thing to do with signal and power integrity ? Is these finishes works only or applies only at top and bottom of the PCB ?
HASL = hot air solder level. Plates the pads with solder. The most common and cheapest.
ENIG = electroless nickel immersion gold. You get gold plated pads, which is useful if the board is going to be stored a long time before use.
ENEPIG = same as ENIG but with an additional layer of palladium.
Palladium is as expensive as gold these days.
As @WBahn says, ask a pcb manufacturer, but HASL is good enough for me!
 

nsaspook

Joined Aug 27, 2009
13,574
I just came to know that we need to tell PCB manufacturer about the surface finish which we don't define or include in the PCB layout in the design tools. What are these PCB surface finishes ? There are options for example, ENIG, ENEPIG, Leadfree HASL etc. Do they have any thing to do with signal and power integrity ? Is these finishes works only or applies only at top and bottom of the PCB ?
I usually prototype in HASL because at least the first or two boards will have revisions on anything complex and it's easier IMO to hand solder parts on. For a high complexity part production level PCB I only use ENIG because the expected work lifetime will be in the decades in a potentially elevated temperature industrial environment. Gold plating gives a stable, lower impedance skin resistance that reduces high frequency signal loss, with higher levels of EM shielding/reflectivity for things like exposed surface ground planes for WFI modules on a PCB design.

https://forum.allaboutcircuits.com/threads/male-header-pins-punching-through-pcb.165323/post-1458432

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https://forum.allaboutcircuits.com/...c-controlled-battery-array.32879/post-1463914
 
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Thread Starter

engr_david_ee

Joined Mar 10, 2023
204
Thanks for your comments. I will check with PCB manufacturer about surface finishes.

One thing which I learned now is that the surface finish is Not solder mask layer in green/red but the surface finish is actually platting on the pads and vias where we can solder. The pads can be tin platted and can be gold platted. What is the difference between these surface finishes I will ask PCB manufacturer.
 
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