Kester 331 Data Sheet

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331

331

Organic Cored W

Organic Cored W

For Lead-bearing and Lead-free alloys

For Lead-bearing and Lead-free alloys

Product Description

Kester 331 Organic Flux is a water soluble formula
for use in flux-cored solder wire. This cored solder
version of the popular 2331-ZX Neutral Organic
Water Soluble Liquid Flux is more effective than
rosin fluxes in soldering difficult metals. The same
fast action and mild properties are exhibited with
331 Organic Flux as with the liquid 2331-ZX. The
flux is more heat st able than most organic fluxes,
resulting in minimal smoke and odor. The residue
can be completely removed with a simple water
rinse.

Performance Characteristics:

• Excellent solderability to a wide variety of
metallizations

• Easy residue removal in DI water

• Compatible with leaded and lead-free alloys

• Classified as ORH1 per J-STD-004

RoHS Compliance

This product meets the requirements of the RoHS
(Restriction of Hazardous Subst ances) Directive,
2002/95/EC Article 4 for the stated banned
substances. (Applies only if this core flux is
combined with a lead free alloy)

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Reliability Properties

Copper Mirror Corrosion: High

Tested to J-STD-004, IPC-TM-650, Method 2.3.32

Corrosion Test: High

Tested to J-STD-004, IPC-TM-650, Method 2.6.15

Silver Chromate: Fail

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

Chloride and Bromides: 1.2%

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

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 331

Day 1
Day 4
Day 7

1.9 ×1010Ω 2.0 × 109Ω

2.2 ×1010Ω 7.8 × 109 Ω

1.7 ×1010Ω 4.1 × 109Ω

Application Notes

Availability:

Kester 331 is available in a wide variety of alloys, wire diameters and flux percentages. For most applications,
Sn63Pb37 or Sn96.5Ag3.0Cu0.5 is used. Consult the alloy temperature chart in Kester's product catalog
for a comprehensive alloy list. The standard wire diameter for most applications is 1.00mm (0.031in). Wire
diameters range from 0.25 - 6.00mm (0.010 to 0.250in). A "Standard Wire Diameters" chart is included in
Kester’s product cat alog. The amount of flux in the wire dictates the ease of soldering for an application.
For most applications, core 58 and 66 (2.2% and 3.3% flux by weight, respectively) are recommended. Core
size 50 (1.1% flux by weight) is also available. Kester 331 is packaged on spools of different sizes to
accommodate a variety of applications.

Process Considerations:

Solder iron tip temperatures are most commonly between 315-371°C (600-700°F) for Sn63Pb37 and
Sn62Pb36Ag02 alloys and 371-427°C (700-800°F) for lead-free alloys. Heat both the land area and component
lead to be soldered with the iron prior to adding Kester 331 cored wire. Apply the solder wire to the land
area or component lead. Do not apply the wire directly to the soldering iron tip. If needed, Kester 2331-ZX
organic flux may be used as a comp atible liquid flux to aid in reworking soldered joints. Kester 2331-ZX is
also available in Flux-Pens

Cleaning:

The 331 flux residue is conductive and may cause corrosion of met al parts over time. Soldered samples left
up to 48 hours in a simulated production environment, without removing the flux, showed no evidence of the
flux residue having any corrosive properties. Kester 331 Organic Flux has the advantage over many
competitive water-soluble flux formulations in that the residue is easily and completely removed with plain
water. No neutralizers. saponifiersor detergents are necessary to completely solubilize the residue. Softened
tap water or deionized water is recommended for high reliability. Use of hard or high mineral content tap
water will lower ionic cleanliness measurements.

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for optimum board cleanliness.

Storage, Handling, and Shelf Life:

Storage must be in a dry, non-corrosive environment. The surface may lose its shine and appear a dull
shade of grey. This is a surface phenomena and is not detrimental to product functionality. Flux cored solder
wire has a limited shelf life determined by the alloy used in the wire. For alloys containing > 70% lead, the
shelf life is two years from date of manufacture. Other alloys have a shelf life of three years from date of
manufacture.

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.