9.1 Solder Mask

In this article:
The solder mask protects the surface against mechanical or chemical influences (corrosion) and prevents short circuits during soldering. It insulates the PCB surface from other elements (e.g., components or enclosures) while optimizing electrical properties (by increasing the flashover voltage).

Data to Be Supplied

The openings of the individual soldering areas should be as large as the soldering area (“zero opening”). In accordance with the tolerances in our manufacturing processes, we increase the opening of the soldering surfaces by 50 µm (all the way around) as standard.

Standard Photosensitive Solder Mask

Feature Value Value
Solder mask lacquer type Peters Group
  • Elpemer 2467 SM DG
 SUN Chemical Circuit
  • Imagecure® XV501T
  • Imagecure® XV501T-4 (*)
Halogen-free ✓ ✓
Solder mask color Semi-matte green Semi-matte green
Surface quality
(acc. IPC-SM840E)		 ✓ (Class H incl. T) ✓ (Class H incl. T)
Dielectric strength [kV/mm]
(acc. IPC-SM840E)		 160 155
Comparitive tracking index [V]
(acc. DIN EN 60112)		 ≤ 600 (Depending
on the base material)		 ≤ 600 (Depending
on the base material)
Dielectric constant/
Permittivity εr (acc. IEC-60250)		 3,7 @ 1 MHz
(based on IPC 4101A)		 3,9 - 4,0 @ 1 MHz
(based on IPC 4101A)
Data sheets Elpemer 2467 SM DG Imagecure® XV501T
Imagecure® XV501T-4

Special Colors

FeatureValue
Solder mask lacquer typeSUN Chemical Circuit
  • Imagecure XV501T, blue, matte black, red
  • Imagecure SMART XV501T-4 gloss black, yellow
Solder mask lacquer typePeters Elpemer SD 2491 SG-TSW, white
Solder mask lacquer typeTaiyo PSR 9000 flexible solder mask, green
Solder mask colorBlue, white, black, red, yellow, flexible solder mask only available in green
Dielectric strengthMaterial-specific (see material data sheets)
Comparitive tracking index CTIMaterial-specific (see material data sheets)
(*) Attention, solder resist type being discontinued!
CodeDescription
Standard
Design to Cost
Advanced
G1Cu thickness of final copper outer layer [µm]< 50≥ 50
S1Thickness of solder mask on edge of copper [µm]> 5≥ 5
S2Thickness of solder mask on base material [µm]35 - 60≤ 140
S3Thickness of solder mask on conductor [µm]6 - 40≤ 120

Frequently asked questions

Are SMD (solder-mask-defined) pads commonly used? How should these be included in the data if the PCB features both SMD pads and classic non-solder mask defined pads (NSMD, sometimes also known as copper-/metal-defined pads)?
Solder-mask defined (SMD) and non-solder mask defined (NSMD) pads are both common. It is up to the layouter to decide which type should be used, with the choice being determined by the layout data of the solder mask. In the case of NSMD pads, there should be an opening of at least 50 µm in the solder mask around the pad. By contrast, in the case of SMD pads, the solder mask should have an overlap measuring at least 20 µm in width all the way around in the border area of the copper pad so that one part of the copper pad is effectively covered by the solder mask.

Keywords

  • Solder mask
  • Solder mask colors
  • Solder mask defined (SMD)
  • Solder mask dams
  • Via tenting
  • PCB data
  • Via sealing
  • Design guidelines
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9.2 Additional Printing | Identification Printing
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