®
R231
Mildly Activated Rosin Solder Paste
Product Description
Kester R231 is a Mildly Activated Rosin (RMA)
solder paste formula specifically designed to
exhibit long stencil/print life. R231 maintains its
activity and printing characteristics for up to 8
hours (temperature and humidity dependent).
• High print speeds to 200 mm/sec (8 in/sec)
• Compatible with 0201 technology
• Excellent printing characteristics to 0.4mm
(16-mil) pitch with Type 3 powder
• Excellent wetting on a variety of substrates,
including OSPs
• Capable of 90 minute break times in printing
• 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-004
• Compliant to Bellcore GR-78 (uncleaned)
• Compatible with DEK ProFlow™ and MPM
RheoPump™ enclosed print head systems
Physical Properties
(Data given for Sn63Pb37 and Sn62Pb36Ag02,
90% metal, -325+500 mesh)
Viscosity (typical):
1600 poise
Malcom viscometer @ 10rpm and 25°C
Initial Tackiness (typical):
42 grams
Tested to J-STD-005, IPC-TM-650, Method 2.4.44
Slump Test:
Pass
Tested to J-STD-005, IPC-TM-650, Method 2.4.35
Solder Ball Test:
Preferred
Tested to J-STD-005, IPC-TM-650, Method 2.4.43
Wetting Test:
Pass
Tested to J-STD-005, IPC-TM-650, Method 2.4.45
Reliability Properties
Copper Mirror Corrosion:
Low
Tested to J-STD-004, IPC-TM-650, Method 2.3.32
Corrosion Test:
Low
Tested to J-STD-004, IPC-TM-650, Method 2.6.15
Standard Applications
90% Metal – Stencil Printing
90% Metal – Enclosed Head Printing
Silver Chromate:
Pass
Tested to J-STD-004, IPC-TM-650, Method 2.3.33
Fluorides by Spot Test:
Pass
Tested to J-STD-004, IPC-TM-650, Method 2.3.35.1
SIR, IPC (typical):
Pass
Tested to J-STD-004, IPC-TM-650, Method 2.6.3.3
Blank
Day 1
Day 4
Day 7
R231
1.5
×10
10
Ω
6.0
×10
9
Ω
5.5
×10
9
Ω
5.3
×
10
9
Ω
2.6
×
10
9
Ω
2.9
×
10
9
Ω
SIR, Bellcore (typical):
Pass
Tested to Bellcore GR-78-CORE
Blank
Day 1
Day 4
R231
2.6
×10
12
Ω
1.8
×10
12
Ω
1.5
×
10
12
Ω
1.5
×
10
12
Ω
R231
Application Notes
Availability:
Kester R231 is available in the Sn63Pb37 and Sn62Pb36Ag02 alloys with Type 3 powder. 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 Solder Paste Packaging Chart for available
sizes. The appropriate combination depends on process variables and the specific application.
Printing Parameters:
Squeegee Blade
Squeegee Speed
Stencil Material
Temperature/Humidity
80 to 90 durometer polyurethane or stainless steel
Capable to a maximum speed of 200 mm/sec (8 in/sec)
Stainless Steel, Molybdenum, Nickel Plated, Brass
Optimal ranges are 21-25°C (70-77°F) and 35-65% RH
Kester Reflow Profile
Alloy: Sn63Pb37 or Sn62Pb36Ag02
Recommended Reflow Profile:
240
The recommended reflow profile for R231 made with
Sn63Pb37 and Sn62Pb36Ag02 alloys is shown here.
This profile is simply a guideline. Since R231 is a
highly active solderpaste, it can solder effectively over
a wide range of profiles. Your optimal profile may be
different from the one shown based on you oven, board
and mix of defects. Please contact Kester if you need
additional profiling advice.
220
200
1.3 - 1.6 C/Sec
180
Peak Temp.
210 - 225 C
Temperature (C)
160
140
120
100
80
60
40
20
0
0
30
.5 - .6 C/Sec
<2.5 C/Sec
Soaking Zone
(2.0 min.max.)
60-90 sec. typical
Reflow Zone
(30-90 sec. max.)
30-60 sec. typical
Pre-heating Zone
(2.0-4.0 min. max.)
60
90
120
150
180
210
240
270
300
Cleaning:
Time (sec.)
R231 is an RMA formula. The residues do not need to be removed for typical applications. Although R231
is designed for RMA applications, its residues can be easily removed using automated cleaning equipment
(in-line or batch) with a variety of readily available cleaning agents. Call Kester Technical Support for details.
Storage, Handling, and Shelf Life:
Refrigeration is the recommended optimum storage condition for solderpaste to maintain consistent viscosity,
reflow characteristics and overall performance. R231 should be stabilized at room temperature prior to
printing. R231 should be kept at standard refrigeration conditions, 0-10°C (32-50°F). Please contact Kester
if you require additional advice with regard storage and handling of this material. Shelf life is 4 months from
date of manufacture when handled properly and held at 0-10°C (32-50°F).
Health & Safety:
This product, during handling or use, may be hazardous to health or the environment. Read the Material
Safety Data Sheet and warning label before using this product.
World Headquarters:
515 E. Touhy Avenue, Des Plaines, Illinois, 60018 USA
Phone:
(+1) 847-297-1600 •
Email:
customerservice@kester.com •
Website:
www.kester.com
Asia Pacific Headquarters
500 Chai Chee Lane
Singapore 469024
(+65) 6449-1133
customerservice@kester.com.sg
European Headquarters
Ganghoferstrasse 45
D-82216 Gernlinden
Germany
(+49) 8142-47850
customerservice@kester-eu.com
Japanese Headquarters
20-11 Yokokawa 2-Chome
Sumida-Ku
Tokyo 130-0003 Japan
(+81) 3-3624-5351
jpsales@kester.com.sg
The data recommendations presented are based on tests, which we consider reliable. Because Kester has no control over the conditions of use, we disclaim any responsibility connected with the
use of any of our products or the information presented. We advise that all chemical products be used only by or under the direction of technically qualified personnel who are aware of the poten-
tial hazards involved and the necessity for reasonable care in their handling. The technical information contained herein is consistent with the properties of this material but should not be used in
the preparation of specifications as it is intended for reference only. For assistance in preparing specifications, please contact your local Kester office for details.
Rev: 09Aug06
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