Solder Mask or Solder Resist Coating is often an area overlooked in today's high end PCB designs.  Solder Mask serves a much higher purpose then just surface color. Solder Masks today, are formulated  with a variety of improved properties.  These masks are more chemical and temperature resistant then their predecessors, developed just a few years ago.  With the advances made in Alternative Surface Finishes, mask suppliers have introduced improvements in the adhesion properties and chemical resistance.  This improvement benefits both fabrication and assembly processes by protecting the surface of the PCB during the harshest processes environments.

Feel free to contact any DFM Engineer directly for additional support and question.

E-mail: dfm@datacircuits.com

(800) 800-3278 Dial "0" and ask for DFM Engineering.

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 Standards:

Today's designs challenge the constraints of application.  The most common questions asked during fabrication tooling are related to solder mask.  Clearance issues, annular ring, web width, and registration are topics addressed daily.

Providing adequate clearance of solder mask for a solderable surface is critical.  As geometries shrink in high density designs the solder mask coverage and exposure ratio becomes more challenging.  The critical process focus is to define the tightest clearance possible and proclude solder mask on surface lands. Below are the standards currently used at Data Circuit Systems.

	Standard	Production Capable
(A) Surface Image Clearance:	.003	.0015
(B) Web Between Surface Mount Pads:	.004	.003
Solder Mask Thickness Over Metal:	IPC Spec Coverage (SPC Ranges .0002 - .003  Typical = .0012)

Many of today's advance CAM Tooling Software offer an ability to modify the solder mask to provide optimum coverage and clearance throughout the design.  Consider generating your solder mask layers 1:1 with the solder land pads.  Notes on the fabrication drawing can communicate requirements to optimize the solder mask.

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Reference Document	Description	Size
Enthone Solder Mask Technical Paper	This document details ENTHONE® DSR-3241 Q Liquid Photo Imageable Solder Mask (LPISM).	866K
Enthone Wave Solder Flux Study	This document details a study done by Enthone regarding compatibility of DSR-3241 Mask with today's assembly methods.	1000K

 

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