The water-soluble solder paste (also known as washable solder paste) is a special type of solder paste for the soldering of electronic components. Unlike other solder pastes, water-soluble solder paste can be dissolved and washed with pure water (deionized water).

The water-soluble solder paste is a new type of soldering material widely used in manufacturing photovoltaic equipment, power electronic devices, smartphones, tablet computers, etc.

In recent years, with the development of the electronic industry and the continuous improvement of technology, the market demand for water-soluble solder paste has increased year by year. According to the market forecast, the consumption of water-soluble solder paste will climb rapidly and is expected to reach its peak in the next few years.

Technical Data
Packaging Details
Physical Properties
Features of Water-Soluble Solder Paste


1. Transfer method: printing, dispensing, and needle transfer;

2. Reflow soldering is recommended for curing;

3. Fitech can provide the users with reflow profiles for reference, which can be used to further discover the optimal reflow

4. The actual reflow profile should be considered regarding the product nature, framework size, chip distribution, and
characteristics, equipment process conditions, and other factors. It is advisable to do more tests in advance to ensure the
optimization of the reflow profile;

5. In addition to the "heating-soak" method, the solder paste with epoxy flux can also adopt the "progressive heating" method;

6. The optimum ambient temperature and humidity for solder paste application are 20-25℃ and 40-60RH%, respectively. The 

solder paste must be reflowed with nitrogen protection. The oxygen concentration should be less than 1000 ppm.

Technical Data of Water-Soluble Solder Paste

Halogen Content



Pass (J-STD-005)

Slump Test

Pass (J-STD-005)

Stencil Life

> 8h In House

Corrosion to Copper Plate


Drying Degree of Residue


Solder Ball Test

Pass (J-STD-005)


Alloy Composition
Particle SizeFlux TypeWashing Method
T5 (15-25μm)

T6 (5-15μm)

T7 (2-11μm)

(Cl+Br<1000 ppm)
Water Rinsing
(Pure Water /Deionized Water)
T5 (15-25μm)

T6 (5-15μm)

T7 (2-11μm)

(Cl+Br<1000 ppm)

Water Rinsing
(Pure Water /Deionized Water)

Packaging Details

1. Packaging

Printed type: Size: 500g/can, 250g/can. The printing solder pastes can be packaged following the customer's requirements. 

The solder pastes are stored in the PE bottles, and inner covers are used for seal. The solder pastes are stored in foam
boxes when delivering.

Dispensing type: The dispensing solder pastes are stored in EFD syringes with the size of 10g/5cc and 30g/10cc.The 

dispensing solder pastes can be packaged according to the customer's requirements. The solder pastes are stored in ice bags, 

foam boxes, and cartons for transportation.

2. Transportation and storage

Transportation conditions: The solder pastes are stored in ice bags when delivering.

Storage conditions: Please put the solder pastes into the refrigerator for storage as soon as possible after receiving them.
The recommended storage temperature is 0~10℃. An excessively high temperature will shorten the service life and properties of the solder pastes.

Physical Properties of Water-Soluble Solder Paste


Light Gray

Alloy Melting Point


Alloy Component Ratio

85~88.5% (Typical Value)

Thixotropy Index

0.5 (Typical Value)


Low / High

Features of Water-Soluble Solder Paste

A. Cleanliness: Water-soluble solder paste can be washed with water, leaving no residue or damage to the electronic 


B. Higher Efficiency: The cleaning speed of water-soluble solder paste is faster than that of other types of solder paste.

C. Residue Reduction: Water-soluble solder paste produces fewer residues after soldering, which guarantees the operation of electronic components.

D. Environmental Protection: The production and cleaning of water-soluble solder paste does not produce contaminants, 

protecting the environment.

E. Overall, water-soluble solder paste is a clean, efficient, and environmentally friendly solder that applies to the soldering of 

components with high cleanliness requirements.

Our engineers will be happy to answer your questions or help you choose the right solder product