Elpemer solder resist: flexible and reliable

In addition to the three features: easy spray or screen printing application, direct or contact exposure and flex-to-install, the Peters solder resist is free from the harmful SVHC photoinitiators 369 and 907. For flexible electronic circuit carriers, SD 2463 FLEX-HF is therefore the ideal product for all fields of application.

The physical and mechanical properties of the solder resist are state-of-the-art. “‘Flex-to-install’ means that the ink is flexible under bending stress when the circuit board is installed,” explains Laboratory Manager Detlev Schucht. As one of its strengths, this solder resist is capable of reliably covering all areas of a PCB that shall not receive solder in subsequent soldering processes. R&D Manager Detlev Schucht explains: “Great hardness and scratch resistance achieved after final curing protect the PCB from mechanical damage in further handling”.

The Elpemer solder resist SD 2463 FLEX-HF is mainly chosen in the automotive and aerospace sectors. “In addition, the fields of application have expanded to sensor technology and medical technology,” reports Michael Kollasa. The Head of Field Sales at Peters presumes that the solder resists will become more important in the field of flexible substrates. Leading manufacturers of demanding flex, rigid-flex and HDI substrates have chosen the Elpemer solder resist SD 2463 FLEX-HF for more than six years now. As an example, for medical technology, Michael Kollasa cites hearing aids that require multiple folded flexible circuit boards in order to take up a minimum of space. “The bending diameters are very small, down to 1mm,” reports Michael Kollasa.

The highly flexible two-component solder resist developed in the Peters labs is a photoimageable ink. Thanks to a resolution of less than 40µm (direct exposure) and its excellent dielectric properties, the protective coating is chosen for ultra-fine conductors and in SMD technology, as an alternative to flexible cover foils. The solder resists of this series are applied by horizontal or vertical double-sided screen printing and are aqueous-alkaline developed.

"They are characterised by fast and easy processability, low exposure energy and resistance in chemical baths," says Sven Kramer, Head of Application Technology at Peters. The solder resist shows an outstanding resistance in chemical and galvanic nickel/gold and chemical tin baths, besides OSP processes.

The criterion ‘free from toxic photoinitiators’ is another advantage of Elpemer solder resist SD 2463 FLEX-HF. "This product is absolutely up to date, reflecting technical progress and meeting international safety standards," emphasises Sven Kramer, who is also Product Manager for the Peters Elpemer family of products. According to Sven Kramer, the criterion ‘without photoinitiator 907 and without other SVHC’ is a unique selling point that Peters can claim for itself.

"After all, we were the first in the world to present a modern and harmless solder resist for both exposure processes," adds Laboratory Manager Detlev Schucht.

Following the Peters expertise in special coatings, the Elpemer solder resist SD 2463 FLEX-HF is halogen-free in accordance with JPCA-ES-01-1999 and has good solder bath resistance even with lead-free solder. In addition, Elpemer solder resist SD 2463 FLEX-HF shows the best flame class UL 94 V-0, UL File No. E80315. This is the registered trademark of Underwriters Laboratories Inc.

The Peters team also points to the constant availability of Elpemer solder resists.