PCB Manufacturing

If you are making a bare PCB then the gerber file is usually sufficient for the printing process.Make sure you explain all the preset positions in the PCB clearly to the PCB manufacturer.If you are taking your PCB to be manufactured by a recommended manufacturer they usually have a look at the gerber file and clarify before making the PCB and in most cases they provide a few samples if the manufacturing is in bulk

Provided that the gerber file contains ALL the necessary layers for the complete fabrication of the board, then that's a good start, but not enough.

What colour is your solder resist to be?

What thickness and flatness is your HASL expected to be?

What side is your primary functional side?

If V-grooved, what taper angle is your processing blade?

What panel perimeter do you need for your processing equipment to handle the final board?

What additional alignment marks do you need on the panel perimeter or individual boards for alignment in your placement machines?

What "resolution" do you need for your solder mask? (Their default may not print solder resist between leads of small chip packs for instance.)

What flatness do you require from your boards? (also warpage)

Do you have any holes with special tolerances? (Remember that they drill boards in stacks and the drills are less precise as the stack is thicker.)

Do you have any special requirements for track adhesion to substrate? (Maybe you need a non-standard adhesive, but probably not.)

If your single PCB is relatively small, how do you want them arranged on a panel?

And the list goes on.

Our usual process is

Send single board Gerber to supplier with proposed panel size.

Supplier responds with our gerber "step and repeat" to propose a full panel layout, including alignment markings on the perimeter and tooling alignment holes for our machines.

We review and confirm.

Supplier sends prototype panels. (Thes must come from the actual fabrication site, not some prototype shop.)

We build and confirm.

We place orders for production volume and everything is sweet. (Usually)

1. FR4 is not lead free process compatible as it does not meet the temperature requirements. Generally, FR4 has a Tg temp of ~120°C. RoHS (or lead free) process compatible boards require the pcb to have Tg be >~170°C.The generic name for lead free process compatible boards is High Tg FR-4.
2. You will also need to specify fiducial size and qty you want on panalized pcb's
3. Usually, full profile routing, v-groove, or mouse bites need to be specified (depending on your board of course)
4. Surface finish
5. Board size/dimensions
6. copper thickness
7. board thickness
8. specify if you want bare board testing (in case there are obvious etching faults on tight boards)
9. Solder resist colour
10. Component reference colour
11. which screens are required
12. Layer stack sequence
13. Above all - make sure that you specify that "all other layers not to be used for fabrication) - trust me it can save you time, money and confusion
14. Class clasification (Class 1, 2 or 3) - see your IPC books.
    

Has your PCB been designed for testability?

You don't know how many companies design boards, then when their production rises, they come to me to get them tested, The first thing I look at is testability, and they reply "Whats that, sorry we are not redesigning our PCB's"

Before designing for testability a board should be designed for manufacturability!

Think of how and who will be populating the bare board! The easier it is to build the better!

NUMBER OF LAYERS is most important. Other than these one main main specification required is Finishing as now a day most of PCB should be ROHS compliance.And also make sure about the date code i.e either it has to etched in the panel or to be marked in Silk screen.Some pcbs require Impedance controll i.e you have to control witdh and spacing of traces very accurately so as to meet the requirement.

Naveen

The previous comments pretty much cover it all nicely. But I've always put these statements in the Drill Drawing Layer art.

The PCB could be produced out by the help of the gerber file. Usually, when our customer send enquiry to us, they just need to let us know the layer of the PCB, the base material( FR4 was the most common base material), the copper clad thickness, the mini line width, the mini line space, the mini hole size, the number of hole, solder mask and silkscreen, we could calculate the cost immediately.

If the design and spec of the PCB is complex, we need double check the gerber file. Gerber file is basic manufacture instruction file of the PCB.

Sincerely

Samina

The other three key factors are panel size, surface finish and IPC standard(I, II or III,etc)

Anyway, when we check customer's file, if we meet questions, we'll confirm with customer.

Sincerely

Samina