Kester Lead-Free Solution™

With over 100 years of soldering technology experience, Kester understands the challenges associated with the transition from leaded to lead-free soldering. Kester's Lead-Free Solutions™ offers the following:

  • Complete line of lead-free materials
  • Kester's know-how to implement lead-free
  • Consulting and training courses in lead-free SMT, wave soldering, and rework.
  • Unique lead-free product packaging
  • Test services

Kester RoHS Ready Logo

 
Kester's commitment to smooth lead-free transition is demonstrated by its "green packaging", the development of uniquely shaped lead-free triangular bar solders for easy identification. Now Kester has gone one step further by developing a RoHS Ready logo.
  • Logo identifies Kester products to be in compliance with RoHS Directive 2002/95/EC Article 4 for banned substances.
  • Can be seen on technical literature such as data sheets.

Kester Lead-Free availale products


Lead-Free Solder Paste
The key variables when converting to Lead-Free SMT processes are the higher reflow temperatures, flux activity, residue characteristics, cleanability, and pin testability. The slower wetting speeds associated with Lead-Free alloys required enhanced flux systems. Kester solder paste have novel flux systems that are specfically designed for Lead-Free assembly. These new flux systems promote good wetting and excellent solder joint integrity at the higher temperatures commonly seen with most Lead-Free alloys such as SnAgCu.
Flux Type
           Formula
No-Clean
Water-Soluble


Tacky Soldering Fluxes for Lead-Free Assembly
Flux Type
           Formula
No-Clean
Water-Soluble
  • TSF-6850
  • TSF-6805L


Lead-Free Solder Wire
To promote rapid and complete wetting of the surfaces to be soldered with lead-free, a flux system with an effective activator package is essential. Kester solder wires have been tested and proved to give good contact angles and shiny joints when using lead-free solders. They are available with all common lead-free alloys.
     
Flux Type
No-Clean
Water-Soluble
                    No-Clean
Rosin Activated
Organic
Formula
275
48
331
Product characteristics Superior wetting performance leaving an extremely clear post-soldering residue. Designed to be a low splattering core flux. Very high activity rosin flux used for difficult to solder metals. Industry standard water washable core for most electrocal and electronic hand soldering.
Residue removal method Not normally required. May be removed by solvent or Kester's 5768 Bio-Kleen® saponifier. Not normally required. May be removed by solvent or Kester's 5768 Bio-Kleen® saponifier. Residue removal is required. Use soft or de-ionized water at temparatures of 49-65°C (120-150°F).

 

Flux-Pens® for Lead-Free
Flux Type
No-Clean
Water-Soluble
                     Low Solids
Rosin Mildly Activated (RMA)
Neutral pH
Formula
952-D6
186-18
2331-ZX
Product characteristics A non-corrosive, halide free liquid flux that is specifically designed for the wave soldering and rework of conventional and surface mount curcuit board assemblies. This comprehensive formulation exhibits excellent wetting characteristics and has superior corrosion inhibiting properties. Provides a non-tacky residue. Suitable for foam or spray fluxing applications. Designed for high thermal stability and superior solderability. Military approved formula for add-on and rework applications. Percent solids (typical): 36 Designed for high thermal stability and superior solderability. Military approved formula for add-on and rework applications. Percent solids (typical): 36 Neutral pH for wave solder flux user who has additional add-on and rework applications.
Residue removal method Not normally required. Not normally required. May be removed by solvent or Kester's 5768 Bio-Kleen® saponifier at 7-10% solution in de-ionized or soft water at 49-60°C (120-140°F) Not normally required. May be removed by solvent or Kester's 5768 Bio-Kleen® saponifier at 7-10% solution in de-ionized or soft water at 49-60°C (120-140°F) Residue removal is required. Use soft or de-ionized water at temparatures of 49-65°C (120-150°F).

 

Liquid Fluxes for Lead-Free Wave Soldering
Lead-Free wave and selective soldering require exposing the flux to slightly higher soldering temperatures. Lead-Free alloys traditionally wet metal surfaces more slowly than tin-lead. Kester liquid fluxes for lead-free assembly have new activator packages to enable wetting and hole-filling, ensuring reliable product output.
Flux Type
No-Clean
Water-Soluble
Alcohol Based
Natural pH Alocohol Based
Formula
985M
959T
2331-ZX
Product characteristics 985M is specially designed to improve effectiveness in the wave soldering of conventional circuit board assemblies. Was developed for excellent solderability and through-hole fill in lead-free wave soldering process. 985M minimized micro-solderballing at connectors and CPU. Its residue left behind is non-tacky, non-corrosive and non-conductive. Designed for lead-free wave soldering. Developed to minimize the formation of micro-solder balls during wave soldering operations. Compatible with spray and foam applications. Original pH neutral organic flux for automated wave and drag soldering processes.
Residue removal method Not normally required. Not normally required. However removal is possible with hot de-ionized water at 60-71°C (140-160°F) with 1% solution of Kester 5768 Bio-Kleen® saponifier. Residue removal is required. Use soft or de-ionized water at temparatures of 49-65°C (120-150°F).

 

Lead-Free Solder Bar
Ultrapure® K100
Kester has developed Ultrapure® K100, a low cost lead-free bar solder. Kester K100 is a near eutectic SnCu alloy with controlled metallic dopants to control the grain structure within the solder joint. This improves reliability of the joint and virtually eliminates the occurrence of common defects such as icicling and bridging. The improved grain structure also results in shinier solder joints than traditional lead-free alloy alternatives. Kester K100 compares favorably to low-cost. lead-free alloys of Sn and Cu in terms of wetting and flow characteristics. Kester K100 provides the lowest delivered price to the global market for wave soldering operations. Kester K100 also provides solder joints with no visible shrinkage effects, excellent through-hole penetration and topside fillet, low dissolution of Cu from boards and components into solder pot and low dross rate.


Wafer and Substrate Bumping Pastes

Kester has leveraged decades of experience in solder paste product development in engineering an extensive selection of wafer and substrate bumping pastes. Bumping of wafers and substrates with solder paste is a growing technology that is low-cost with high yields and competitive quality. Kester's array of bumping pastes supports flexible, high volumn applications. Contact Kester for assistance in finding an optimized solution.

 
Flux Type No-Clean Water-Soluble
Fomular Se-Cure® 7601 Se-Cure® 7101
Application Metal Foils and Organic In-Situ Stencils Metal Foil Stencil
Product Characteristic Designed for substrate, wafer-bumping and ultra-low pitch printing operations. Se-Cure® 7601 thermally stable fluxing system is compatible with both eutectic SnPb and lead-free (SnCu, SnAg, and SnAgcu) alloys. This high activity paste exhibits long stencil life while still delivering exceptional solderability and low voiding. Designed for wafer bumping and ultra-low pitch bumping applications, Se-Cure® 7101 is a thermally stable flux system that reduces voiding in FC and CSP. When using Se-Cure® 7101, the voiding level of FC and CSP's has been reduced from 25% to less than 10%. It releases cleanly from stencil apertures up to area ratio of 1.5 (mesh size dependant) without slumping or flux bleed out and with optimal deposit definition. The activator package has been formulated to exhibit exceptional wetting characteristics to many different Under Bump Metallurgies (UBM) and is available in Sn63Pb37, lead-free alloys, low alpha, and ultra-low alpha solder alloys.
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