Posts Tagged ‘PCB soldermask’

Soldermask on Hole (Via) Without Opening

Thursday, October 6th, 2016

Soldermask opening always is a very important thing for various PCB, esp. for rigid FR4 PCB. In previous article, we already discussed why soldermask opening & tented was not the same like original gerber file.

If you really want soldermask opening for hole (Via) less than 0.60mm, you should added special notice when placing order.

At the same time, there’s another method you can use: To increase the soldermask opening diameter, that means add an “Annular Ring”. Normally you will need to increase 0.10mm (4mil) on each side, so that there’ll be a 0.1mm “Annular Ring” around the hole/Via, that Annual ring will stop soldermask into the hole/via of PCB.

Because in a lot of design, if there’s Via/Hole, there’ll no opening in its soldermask file, maybe engineer think the drill will remove the soldermask and then there’ll no soldermask on these Via/hole of board. As mentioned before, if Via/Hole in Printed circuit board was less than 0.6mm, or around 0.65mm then it’ll be a problem.

See from bellowing pictures of PCB board:

0.635mm Drill hole (Via)

0.635mm Drill hole (Via)

(0.635mm Drill hole (Via)

This is the original PCB Gerber file, the diameter of drill hole was 0.635mm and there’s no soldermask opening on GTS (top soldermask) Gerber file. (Purple color was GTS, Yellow: GTL (top layer); Blue: Drill (PTH) file), and no Annular Ring.

So final circuit boards will be like belowing:

0.635mm Via covered/tented by soldermask

0.635mm Via covered/tented by soldermask

 

 

 

 

 

 

 

 

 

 

 

So you need to add at least 0.10mm (4mil) soldermask opening on each side of hole, so that there’ll be a 0.1mm Annular Ring, like bellowing:

Add 4mil Annular Ring on PCB Via

Add 4mil Annular Ring on PCB Via

 

 

 

 

 

 

 

 

 

 

Then that hole will become like bellowing:

Hole/Via without soldermask (soldermask opened)

Hole/Via without soldermask (soldermask opened)

 

 

 

 

 

 

 

 

 

 

We believe there’re a lot of other handling method about that soldermask opening, please leave your comments, or contact us to discuss more about that, and believe you will be happy to receive with the PCB with correct soldermask opening!

Why Soldermask Opening or Tented was not the same like the Original Gerber file?

Monday, August 29th, 2016

Recently customer compliant that the soldermask for some holes, esp for PTH (plated through hole, sometimes people named Via) was wrong, because in his original Gerber file, it was opened, but on actual printed circuit board, it was tented (covered), and some cases, some was tented and some was opened at the same time. It made customer confused.

In fact, there’s a default rule in PCB (printed circuit board) manufacturing: If the PTH (Via) was less than 0.60mm, then the soldermask will be made as per factory’s default rules: making them as tented (covered), regardless it was tented or opened in customers’ original Gerber file.

Here you can see pictures showing a board with a 0.30mm PTH, soldermask was opened in original Gerber file, but in real board, it was tented.

0.3mm Via soldermask

0.3mm Via soldermask

And in this board, for 0.508mm PTH (via), some soldermask was opened and some was opened.

0.508mm Via soldermask

0.508mm Via soldermask

Why like that? Here are two major reasons:

1) For PTH(via) less than 0.6mm, normally the function was only to electrically connected trace, not for electronic components assembled; so whatever PTH was opened or tented, it doesn’t matter.
2) In rigid printed circuit board manufacturing, it’s not easy to etch away the soldermask around PTH less than 0.60mm. As soldermask was made by that method: printed whole area with oil (soldermask), then undergo develop & exposure, then pass the etching line. The chemical will etch away the oil accordingly to the drawing, but if the hole was too small (less than 0.60mm), then the oil around will be very difficult to etch away, so you will see some oil was etched away (soldermask opened), some oil still here (soldermask tented)

If diameter of hole was bigger than 0.60mm, then it’ll be easy to etch away and some of them will be used in assembly, so we will make according to Gerber file and you will see the board exactly like the drawing. See bellowing a picture showing a board with 0.889mm (0.035mil) PTH.

0.889mm Via soldermask opening

0.889mm Via soldermask opening

Sometimes, people just use these hole as testing point, not for assembly, then we suggest to add another PAD connected to this hole so that you can test it easy. To tested on hole was not stable as tested on a PAD.

In a conclusion, in future, if the hole was less than 0.60mm and you really want it to be opened, please add special notes when release order, and allow us to enlarge the opening diameter of soldermask (around 0.60mm) so that soldermask of these holes will be opened.

Please contact us if still any question about soldermask opening.

New Automatic Solder paste Printer Adopted in SMT & PCBA

Thursday, August 25th, 2016

Great news! We (Best Technology) had adopted a new Automatic Solder paste printer for SMT /PCBA since Aug 25th, 2016. We use “G5” which is No. 1 brand in domestic market, made by a Chinese company, the repeated position accuracy is +/-0.01mm, and printing accuracy is +/-0.025mm.

Everybody know the most important element which will affect the quality of SMT /PCBA is the solder past printing quality. Excellent solder paste printing is the base for excellent quality of final SMT /PCBA quality, esp. for the small components such as SMD Chips with small size as 0402, 0201, 01005; IC with small pitch package such QFN, LGA, BGA; Connector with 0.25mm, 0.3mm, 0.40mm pitch.

Here are some pictures of new Automatic Solder paste printer.

Auto Solder Paste Printer

Auto Solder Paste Printer

Auto Solder Paste Printer printing the board

Auto Solder Paste Printer printing the board

Auto Solder Paste Printer with PCB printing

Auto Solder Paste Printer with PCB printing

PCB with solder paste

PCB with solder paste

Welcome customers release more SMT /PCBA orders to us. To learn more about Automatic Solder paste printer, or our SMT /PCBA service, please contact us right now!