Some questions about pcb design

[atmaca]

There are some layers in any pcb design CAD tool.

Some of them are ;
silk,
mask,
assembly,
paste,

Can somebody explain these layers and if available on a pcb) other layers.

Thanks.

 

[gam]

Hello,

The conventional PCB layers usually:

- Top: Top copper tracks , solder side
- Bottom: Bottom copper stracks, component side (used if double sided)
- Layer #x: x is a number, for multi-layer(>2 side) boards.

- Silk layer: Silkscreen printing on top and bottom layers to identify component names and values and shapes to facilitate assembly. This is usually the white text on the PCB.

- Mask: Is the mask used to develop one of the copper tracks layers, it contains the shape (or inverted shape depending on your photoresist type) of the tracks

- Paste: This is a mask for the solder paste, it covers everything in the board except the pads of the components where there is going to be soldering.

Regards,

gam

 

[atmaca]

Hello gam,

Thank you very much for your kind explainations,

But I have confused some points. If top layer can spesify the copper tracks why the mask layer is used to specify the field for photoresist. I mean "is the top layer sufficient to specify coupper tracks ?".

Thank you very much.

atmaca

 

[WA]

The mask layer refers to the solder mask.

the top layer (in your question) is only concerned with the coppor trace routing for each component.

the mask layer is the covering over the coppor on board.
When you solder your board, the mask prevents solder from flowing where you don't want it.
for example: solder flowing (jumping) from one trace to another and creating a short circuit.

Hope this helps
WA

 

[SphinX]

Hi,

PCB Design Tutorial


Bye

 

[majnoon]

atmaca
As Wa correctly pointed out mask layer is to expose pads for soldering, remember mask layer is positive so what you see in your gerber mask is going to be cleared.

As for the Paste is only used for SMD componants to creat paste mask for assembly.

Majnoon

 

[lguancho]

Hi, usually, PCB manufacturers usually need additional board info like NCdrill file (text file), mechanical outline (usually 1 of the layer)

Most CAD tool can generate these files 8)

 

[EEHardware]

i can not know about:
silk,
mask,
assembly,
paste,

but we use:
top
gnd
power
bottom

for 4 layers

 

[atmaca]

If you use PCAD you can see these layers

 

[btbass]

These are not physical layers.
The silk layer is the component idents printed on top of the board, the mask is the solder resist, which is normaly a little bit bigger than the component pads, the assembly is for you when you are placing the components so they dont crash into each other and the paste is only required for flow solder assembly, the solder paste is applied like a silk screen, then the components are glued into place, (glue spot layer) and flowed through an oven!