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Protectostan® LF

Our unique post-treatment designed to mitigate corrosion whisker formation in tin surfaces

Effective corrosion protection

For tin-plated surface finishes on IC outer leads

Effective whisker mitigation

Successfully mitigates the formation of whiskers within heat and humidity

Tarnish
prevention

Excellent solderability after hot and humid storage

Electroplating whisker prevention
  • Effective corrosion protection for tin-plated surface finishes on IC outer leads
  • Successfully mitigates whisker formation within heat and humidity to comply with the iNEMI / Jedec storage conditions (4,000 h at 55 °C / 85% RH)
  • Prevents tarnishing within hot and humid storage conditions
  • Excellent wettability and solderability after steam aging and pressure cooker test conditions
  • Protectostan® LF coating is not affected by the postbaking operation (1 h at 150 °C)
  • According to TOF-SIMS, Protectostan® LF can withstand multiple reflow cycles
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  • Protectostan® LF post-dip is followed by rinsing and drying. In production, it can also be used as either a neutralization or rinse stage and is thus easily integrated into existing systems
  • Can be applied to all types of tin surfaces

Protectostan® LF

A unique post-treatment to mitigate corrosion whisker formation

 

Protectostan® LF is a slightly acidic post-treatment process developed especially for tin and tin alloy surfaces. It was designed to prevent tarnishing during storage – which can lead to solderability problems later on – and to mitigate corrosion whisker.

Protectostan® LF reduces the detrimental oxidizing effects of exposed copper to adjacent tin surfaces, effectively mitigating the formation of tin whiskers during heat / humidity storage. The product has also been tested according to iNEMI/JEDEC specifications with different package types of differing leadframe alloy base materials.

Protectostan® LF prevents all kinds of tin surface discolorations associated with heat / humidity storage conditions, such as those acquired during pressure cooking and steam aging. Furthermore, it has been designed to preserve the white finish of a plated tin layer – even during undefined, long-term storage.

This effective corrosion protection also contributes to improved solderability after steam aging and pressure cooker testing. This is particularly important at low reflow temperatures (220 °C or lower). Solderability tests after steam aging were used to evaluate Protectostan® LF’s efficacy against corrosion. Additionally, different post-treatment sequences were tested in order to assess the adaptability of Protectostan® LF to existing plating lines.

What inspires us

Why we developed Protectostan® LF

Your challenge

The propensity of pure matt tin layers to whisker has become a major concern in terms of implementing this technology as a lead-free solderable finish for IC assembly.

Our solution

Protectostan® LF reduces the detrimental oxidizing effects of exposed copper to adjacent tin surfaces, effectively mitigating the formation of tin whiskers during heat / humidity storage.

Our extensive corrosion and whisker investigations

We carried out extensive studies on the influential parameters for whisker formation.

Our studies illustrate the influence of the neutralizing post-treatment (post dip A) on corrosion through a reduction in the formation and length of corrosion whiskers – a result which encouraged us to develop Protectostan® LF. All tests were carried out under production conditions.

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