Lead-Free Solder Pastes


The key variables in lead-free SMT are the higher reflow temperatures, flux activity, residue characteristics, cleanability, and pin testability. The slower wetting speeds associated with lead-free alloys require enhanced flux systems. Kester solder pastes have innovative flux systems that are specifically designed for lead-free assmebly. 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 Sn-Ag-Cu (tin-silver-copper).

Formula EnviroMark™ 907
No-Clean
EnviroMark™ 808
Water-Soluble
R520A
Water-Soluble
NXG1
No-Clean
Kester
Part No.
500g Jar 70-0605-0810 70-0306-0810 70-1903-0810 70-3213-0810
600g Cartridge 70-0605-0811 70-0306-0811 70-1002-0511 70-3213-0811
Application No-Clean
Stencil Printing
Water-Soluble
Stencil Printing
Water-Soluble
Stencil Printing
No-Clean
Stencil Printing
Product
Characteristics
Designed to exceed customers' expectations for high yeild lead-free manufacturing. EM907 is engineered for the high thermal demands of assembling with lead-free alloys such as the family of SnAgCu (SAC). Joints are as cosmetically bright as SnPb joints. Prints down to 0201 pad sites. Designed to be reflowable in air as well as nitrogen. Kester EM808 provides hours of stable stencil life, tack time and repeatable print definition. EM808's robust printing characteristics result in consistent solder paste volume regardless of idle time and print speed. The activator package is very aggressive and provides superior wetting to OSP coated and Immersion Silver boards. R502A is designed to solder effectively difficult metal surfaces in an air or nitrogen reflow atmosphere. The activator package is able to withstand the higher temperatures without slump. The flux system is non-hygroscopic, reducing paste waste at the printer. It is available in all common lead-free alloys. NXG1 represents a breakthrough in lead-free technology with a best-in-class combination of superior wetting behavior, shiny joints, excellent printing and the longest shelf life available. Superior solderability, ultra-low BGA vioding, reduced ball-in-socket defects, excellent printability and clear, probeable residues will satify all you assembly needs. With an 8 month shelf life, NXG1 will help reduce scrap and waste while allowing for a more manageable inventory.
Residue
Characteristics
Light Colored Cleanable in Warm Water Cleanable in Warm Water Light Colored
Copper
Mirror Corrosion
Low High High Low
Halide Tests Halide-Free Halide-Free Halide-Free Non Halide-Free
Surface Insulation
Resistance
Pass (Uncleaned) Pass (Cleaned) Pass (Cleaned) Pass (Uncleaned)
Printing
Characteristics
Excellent to 16 mils pitch (0.4 mm) Excellent to 16 mils pitch (0.4 mm) Excellent to 16 mils pitch (0.4 mm) Excellent to 16 mils pitch (0.4 mm)
Idle Time 60 Minutes at 70°-77°F
and 40-60% R.H.
60 Minutes at 70°-77°F
and 40-60% R.H.
90 Minutes at 70°-77°F
and 40-60% R.H.
70°-77°F
and 40-65% R.H
Maximum
Print Speed
Up to 150 mm/sec Up to 150 mm/sec Up to 150 mm/sec Up to 200 mm/sec
Typical Metal Percentage 88.5% Type III Powder
for Stencil Printing
88% Type III Powder
for Stencil Printing
89.5% Type III Powder
for Stencil Printing
88.5% Type III Powder
for Stencil Printing
Expected
Stencil Life
12+ Hours at 70°-77°F
and 40-60% R.H.
8+ Hours at 70°-77°F
and 40-60% R.H.
8+ Hours at 70°-77°F
and 40-60% R.H.
Process Dependent
Reflow Atmosphere Air or Nitrogen Air or Nitrogen Air or Nitrogen Air or Nitrogen
Compliant
Specifications
Telcordia Issue 1
GR-78-CORE
IPC/J-STD-004
Flux Designator ROLO
IPC/J-STD-004
Flux Designator ORMO
IPC/J-STD-004
Flux Designator ORHO
IPC/J-STD-004
Flux Designator ROL1