®
Technical Data Sheet
EP256 Solder Paste
No-Clean
Product Description
EP256 is a no-clean, air or nitrogen reflowable, solder paste specifically designed for maximum robustness in reflow pro-
filing and stencil printing. EP256 has the widest possible reflow processing window. EP256 is capable of stencil printing
downtimes of up to 90 minutes with an effective first print down to 20 mils. EP256 is a solder paste formula that maintains
its activity and printing characteristics for up to 8 hours without any shear thinning.
Performance Characteristics:
■
Stable wetting behavior over a wide
range of profiles
■
Capable of 90 minute break times in
printing
■
High print speeds to 200+mm/sec
(8+ in/sec)
■
Compatible with enclosed print head
systems
Standard Applications:
Stencil Printing: 90% Metal
Enclosed Head Printing: 90% Metal
■
Excellent printing characteristics to
0.4mm (16 mil) pitch with Type 3
powder
■
High activity on all substrates,
including OSPs
■
Capable of off-pad printing with no
solder balls after reflow
■
Stencil life: 8+ hours (process
dependent)
■
Scrap is reduced due to less paste
dry out
■
Stable tack over 8+ hours
■
Classified as ROL0 per J-STD-004B
■
Compliant to Bellcore GR-78
RoHS Compliance
Kester does not determine any applicable Restriction of Hazardous Substances (RoHS) exemptions for our lead
containing products at the user level.
Physical Properties
Data given for Sn63Pb37, 90% metal, -325+500
mesh)
Initial Tackiness (typical):
40 grams
Tested to Kester Method 1W-QC-3-04
Solder Ball Test:
Pass
Wetting Test:
Pass
Tested to J-STD-005, IPC-TM-650, Method
2.4.43
Tested to J-STD-005, IPC-TM-650, Method
2.4.45
Viscosity (typical):
1400 poise
Malcom Viscometer @ 10rpm and 25°C
Slump Test:
Pass
Tested to J-STD-005, IPC-TM-650, Method
2.4.35
Reliability Properties
Copper Mirror Corrosion:
Low
Corrosion Test:
Low
Tested to J-STD-004B, IPC-TM-650, Method
2.3.32
Tested to J-STD-004B, IPC-TM-650, Method
2.6.15
Chloride and Bromides:
None
Detected
Fluorides by Spot Test:
Pass
Tested to J-STD-004, IPC-TM-650, Method
2.3.35
Tested to J-STD-004, IPC-TM-650, Method
2.3.35.1
Surface Insulation Resistance (SIR):
Pass
Tested to J-STD-004, IPC-TM-650, Method
2.6.3.3
Blank
Day 1
Day 4
Day 7
1.0*10 Ω
10
EP256
9.8*10
8
Ω
1.6*10
9
Ω
1.1*10
9
Ω
1.3*10
10
Ω
1.3*10
10
Ω
Silver Chromate:
Pass
Surface Insulation Resistance (SIR):
Pass
Tested to J SIR J-STD-004B, IPC-TM-650,
Method 2.6.3.7
Tested to J-STD-004B, IPC-TM-650, Method
2.3.33
Global Headquarters: 800 West Thorndale Avenue, Itasca, IL USA 60143
■
Phone: +1 800.2.KESTER
■
Fax: +1 630.616.4044
Asia-Pacific Headquarters: 61 Ubi Avenue 1 #06-01 UB Point, Singapore 408941
■
Phone: +65 6.449.1133
■
Fax: +65 6.242.9036
European Headquarters: Ganghofer Strasse 45, 82216 Gernlinden, Germany
■
Phone: +49 (0) 8142 4785 0
■
Fax: +49 (0) 8142 4785 61
Asia Manufacturing: Hengqiao Road, Wujiang Economic Development Zone
■
Suzhou, Jiangsu Province, China 215200
■
Phone: +86 512.82060807
■
Fax: +86 512.8206 0808
■
Website: www.kester.com
■
Application Notes
Availability
EP256 is commonly available in the Sn63Pb37 and Sn62Pb36Ag2 alloys. Type 3 powder mesh is recommended, but
different powder particle size distributions are available for standard and fine pitch applications. For specific packaging
information, see Kester’s website for available sizes. The appropriate combination depends on process variables and the
specific application.
®
Printing Parameters
Squeegee Blade
Squeegee Speed
Stencil Material
Temperature/Humidity
Stainless Steel or 80-90 Durometer Polyurethane
Capable to a maximum speed of 200 mm/sec (8 in/sec)
Stainless Steel, Molybdenum, Nickel Plated or Brass
Optimal ranges are 21-25°C (70-77°F) and 35-65% RH
Kester Reflow Profile
Alloy: Sn63Pb37 or Sn62Pb36Ag02
240
220
200
Recommended Reflow Profile
The recommended reflow profile for EP256 made with either the Sn63Pb37 or
Sn62Pb36Ag02 is shown here. This profile is simply a guideline. Since EP256 is a highly
active solder paste, it can solder effectively over a wide range of profiles, including lead-free
profiles in some cases.
EP256 is capable of reflowing at the 235°C peak temperatures required for fully collapsing
lead-free SAC BGA’s for maximum reliability, and remains easy to clean after these high
temperature profiles. Your optimal profile may be different from the one shown based on
your oven, board and mix of components.
Contact Kester Technical Support if you need additional profiling advice.
Peak Temp.
210-230 C
180
Temperature (C)
160
140
120
100
80
60
40
20
0
0
30
60
90
120
150
180
210
240
270
300
330
<1.8 C/Sec
(120 sec. max.)
30-60 sec. typical
Soaking Zone
(90 sec. max)
45-75 sec. typical
Reflow Zone
Time to Peak Temperature
3.5-5.0 min. typical
5.5 min max
Time (sec.)
Cleaning
EP256 is a no-clean formula. The residues don’t need to be removed for typical applications. Although EP256 is designed
for no-clean applications, its residues can be easily removed using automated cleaning equipment (in-line or batch) with a
variety of readily available cleaning agents.
Storage, Handling and Shelf Life
Refrigeration is the recommended optimum storage condition for solder paste to maintain consistent viscosity, reflow
characteristics and overall performance. EP256 should be stabilized at room temperature prior to printing. EP256 should
be kept at standard refrigeration conditions, 0-10°C (32-50°F). Contact Kester Technical Support if you require additional
advice with regard storage and handling of this material. Shelf life is 6 months from the date of manufacture when handled
properly when held at 0-10°C (32-50°F).
Health and Safety
This product, during handling or use, may be hazardous to your health or the environment. Read the Safety Data Sheet
and warning label before using this product.
Global Headquarters: 800 West Thorndale Avenue, Itasca, IL USA 60143
■
Phone: +1 800.2.KESTER
■
Fax: +1 630.616.4044
Asia-Pacific Headquarters: 61 Ubi Avenue 1 #06-01 UB Point, Singapore 408941
■
Phone: +65 6.449.1133
■
Fax: +65 6.242.9036
European Headquarters: Ganghofer Strasse 45, 82216 Gernlinden, Germany
■
Phone: +49 (0) 8142 4785 0
■
Fax: +49 (0) 8142 4785 61
Asia Manufacturing: Hengqiao Road, Wujiang Economic Development Zone
■
Suzhou, Jiangsu Province, China 215200
■
Phone: +86 512.82060807
■
Fax: +86 512.8206 0808
■
Website: www.kester.com
■
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