Flux

Flux chemically removes oxide film from the metal surface to be soldered, thereby exposing the solderable metal surfaces. Flux is therefore indispensable in all soldering processes, including soldering of PC boards and special metals. It requires high reliability and soldering properties that match the application. SMIC has long experience in developing various types of flux, including PC board flux, all of which provide unrivaled performance.

SPARKLE FLUX ES SERIES

ES series Sparkle Flux is a post-flux developed for the Lead-Free soldering of PC boards. Lead-Free solder has rather poor solder wettability compared with existing Sn-Pb solder. However, solder bridges, icicles, blow holes and other problems in Lead-Free soldering can be reduced to a level equivalent to those of existing Sn-Pb solders with the use of the ES series Sparkle Flux.

Products Solid
content
Chroline
content
Specific
gravity
(20°C)
Remarks
ES-1061SP-2 15% 0.09% 0.826 Prevents bridging of ES-1061, good finish in through-hole
ES-1077 7% 0.04% 0.804 Low residue
ES-0307LS 15% 0.07% 0.826 Low Ag content, Sn-Cu alloy, good wettability, good lusterless finsh
ES-0307LS-PD 15% 0.07% 0.826% Point soldering

SPARKLE FLUX ESR SERIES

ESR series Sparkle Flux is a highly reliable post-flux. If existing flux for Sn-Pb soldering is used for Lead-Free soldering, a large number of solder bridges, icicles and blow holes may be generated. ESR series Sparkle Flux exhibits the highest degree of wettability among RMA type fluxes and produces excellent soldering results.

Products Solid
content
Chroline
content
Specific
gravity
(20°C)
Remarks
EZR-01S 7% 0.01% 0.086 RMA type, low residue
ESR-250T4 15% 0.0% 0.822 RMA type, best for both sides P.C.B.
ESR-280 9% 0.012% 0.810 Lower solid content type of ESR-250T4

Comparison of Wettability in Lead-Free Soldering and Zero-cross Time

(by Temperature)

Test equipment: SAT-5100 made by RHESCA
Test piece size: 30 x 5 x 0.3 mm
Test piece: Copper oxide plate (processed at 150°C for 60 min.)
Dipping depth: 2 mm
Dipping speed: 15 mm/sec

Recommended soldering conditions

Flux application

1) Flux must be applied by foaming, spraying, etc.

2) Use a stainless steel container for storing flux.

Preheating

1) Preheating must be implemented in order to ensure the evaporation of solvent, heating of the PC board pad and parts electrode and activation of the flux.

2) Recommended preheating temperature is 100 - 130°C (at the soldering surface).
Limit to 100 - 110°C to prevent PC board warping.
If through-hole spreading is poor, set the temperature at around 120 - 130°C (at the soldering surface).

3) Although the recommended preheating time is 30 - 60 seconds, solvent can be vaporized with longer preheating. Preliminary heating with hot air is also effective.

Soldering

1) Set soldering temperature at 250 - 255°C.

2) For the wave soldering bath, set the soldering time between 3 - 5 seconds.