Kester 959T Data Sheet

®

959T

959T

Low-Solids No-Clean Liquid Flux

Low-Solids No-Clean Liquid Flux

Product Description

Kester 959T is a no-clean, non-corrosive, liquid
flux that is designed for the wave soldering of con­ventional and surface mount circuit board assem­blies. Kester 959T was developed to minimize
the formation of micro-solderballs during wave
soldering operations. This flux contains a small
percentage of rosin (0.5%), which improves
solderability, heat stability and surface insulation
resistance. Kester 959T offers the best wetting
and the shiniest solder joints of any no-clean,
solvent-based chemistry. Kester 959T leaves
evenly distributed residues for the best cosmetic
appearance.

Performance Characteristics:

• Minimize micro-solderballs

• Extremely shiny joints

• No streaky, white residues

• Improves soldering performance

• Eliminates the need and expense of cleaning

• Classified as ORL0 per J-STD-004

• Compliant to Bellcore GR-78

Physical Properties

Specific Gravity: 0.794 ± 0.005

Antoine Paar DMA 35 @ 25°C

Percent Solids (typical): 2.9

Tested to J-STD-004, IPC-TM-650, Method 2.3.34

Acid Number: 21.0 ± 1.0 mg KOH/g of flux

Tested to J-STD-004, IPC-TM-650, Method 2.3.13

Flash Point: 18°C (64°F)

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

Silver Chromate: Pass

Tested to J-STD-004, IPC-TM-650, Method 2.3.33

Chloride and Bromides: None Detected

Tested to J-STD-004, IPC-TM-650, Method 2.3.35

RoHS Compliance

This product meets the requirements of the RoHS
(Restriction of Hazardous Substances) Directive,
2002/95/EC Article 4 for the stated banned

substances.

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 959T PD

Day 1

Day 4

Day 7

7.9 ´109W 1.6 ´ 109W

8.4 ´109W 1.9 ´ 10

9

W

7.4 ´109W 1.9 ´ 109W

959T PU

1.7 ´ 109W

5.3 ´ 109W

2.8 ´ 109W

959T

Application Notes

Flux Application:

Kester 959T can be applied to circuit boards by a spray, foam or dip process. Flux deposition should be

2

120-240 mg of solids/cm
remove excess flux from the circuit board and prevent dripping on the preheater surface.

Process Considerations:

The optimum preheat temperature for most circuit assemblies is 90-105°C (194-221°F) as measured on the
top or component side of the printed circuit board. Dwell time in the wave is typically 2-4 seconds. The wave
soldering speed should be adjusted to accomplish proper preheating and evaporate excess solvent, which
could cause spattering. For best results, speeds of 1.1-1.8 m/min (3½-6 ft/min) are used. The surface tension
has been adjusted to help the flux form a thin film on the board surface allowing rapid solvent evaporation.

Flux Control:

Acid number is normally the most reliable method to control the flux concentration of low solids, no clean
fluxes. To check concentration, a simple acid-base titration should be used. PS-22 Test Kit and procedure
are available from Kester. Control of the flux in the foam flux tank during use is necessary for assurance of
consistent flux distribution on the circuit boards. The complex nature of the solvent system for the flux makes
it imperative that Kester 4662 Thinner be used to replace evaporative losses. When excessive debris from
circuit boards, such as board fibers and from the air line build up in the flux tank, these particulates will rede­posit on the circuit boards which may create a build up of residues on probe test pins. It is, therefore, nec­essary to clean the tank and then replenish it with fresh flux when excessive debris accumulates in the flux
tank.

(750-1500 mg of solids/in2). An air knife after the flux tank is recommended to

Cleaning:

Kester 959T flux residues are non-conductive, non-corrosive and do not require removal in most applications.

Storage and Shelf Life:

Kester 959T is flammable. Store away from sources of ignition. Shelf life is 3 years from date of manufacture
when handled properly and held at 10-25°C (50-77°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: 800 W. Thorndale Avenue, Itasca, Illinois, 60143 USA

Phone: [phone] • Email: [e-mail] • Website: www.kester.com

Asia Pacific Headquarters

500 Chai Chee Lane

Singapore 469024

([phone]

[e-mail]

European Headquarters

Zum Plom 5

08541 Neuensalz

Germany

([phone]

[e-mail]

Japanese Headquarters

20-11 Yokokawa 2-Chome

Sumida-Ku

Tokyo 130-0003 Japan

([phone]

[e-mail]

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 poten­tial 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: 22Mar10