The Mechanism of Flux

Fine-pitch flux assists in the manufacturing, assembly, and packaging of microelectronics and semiconductors. It is suitable for high precision and reliability packaging of wafer bumping soldering, chip evaporation soldering, BGA, SiP, CSP, Micro LED packaging, module integrated circuits, etc. Fitech's zero-halogen epoxy flux has self-assembly and self-correction functions. Epoxy curing after soldering provides excellent insulation, corrosion resistance, and reliability performance, and it is compatible with underfill and bonding. It can be used in the printing or dispensing process.

The epoxy flux (zero halogens) has the function of self-assembly and self-correction. The epoxy resin cured after soldering can improve the insulation and corrosion resistance of the solder joints. Besides, the epoxy flux is compatible with the underfill and bonding adhesive. The epoxy flux can be released to substrates through printing or dispensing.

Technical Data
Physical Properties
Features of Epoxy Flux
Packaging Details


Flux VehicleHalogen ContentFluxWashing Method
PrintingEpoxy Resin

Cl+Br<900 ppm


Cl+Br<900 ppm


Cl+Br<900 ppm


Technical Data of Epoxy Flux

Halogen Content

Cl+Br < 900 ppm (J-STD-004B)



Copper Mirror Test

Pass (IPC-TM-650 2.3.32)


Pass (J-STD-005)

Corrosion to Copper Plate

Pass (J-STD-004)

Silver Chromate Paper Test

Pass (J-STD-004)

Surface Insulation Resistance

Pass (JIS Z3197-2012)

Physical Properties of Epoxy Flux




Milk White


< 30μm

Thixotropy Index

0.5 (Typical Value)



Features of Epoxy Flux

A. The epoxy flux is suitable for wafer bump soldering, evaporation soldering of chips, BGA soldering, and others;

B. The epoxy flux has the function of self-assembly and self-correction;

C. The cured epoxy resin improves the insulation and corrosion resistance of solder joints, increasing reliability;

D. Simple operation. Heating devices such as reflow furnaces, electric heating plates, and ovens can be used;

E. The epoxy flux is compatible with the underfill, bonding adhesives, etc.;

F. Compared with rosin-based flux, epoxy-based flux has higher mechanical strength after soldering.

G. The epoxy flux adopts zero-halogen formulation. Therefore, it is environmental protection.

Packaging Details

1. Packaging

Can: Size: 50g/can. The epoxy flux is stored in the PE bottles, and inner covers are used for seal. The solder pastes
are placed in foam boxes when delivering.

Syringe: The epoxy flux is stored in EFD syringes with the size of 20g/30cc.The epoxy flux 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 epoxy flux is stored in ice bags when delivering.

Storage conditions: Please put the flux into the refrigerator for storage as soon as possible after receiving it. The
recommended storage temperature is -20±5℃. An excessively high temperature will shorten the service life and properties of
the flux.


1. Transfer method: Jetting;

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.


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