N₂ System

N₂ System Effect

Do you have any trouble with soldering defects?

N₂ System prevents soldering defects.

	Examples of soldering defects	Effect of N₂ System that prevents soldering defects
A	・Solder bridging ・Solder projection/Icicle ・Insufficient solder vertical fill of PTH ・Soldering defects caused by insufficient heat	Antioxidant effect and preheating effect by N₂ gas
B	Damaged components (capacitor, LED, etc.) by rapid heating	Preheating effect

In soldering, ”wetting” is the phenomenon that melted solder contacts with metal surface and flows and spreads over the surface. “Wettability” means a spontaneous solder spreading.

A：In case of solder bridging, solder projection/icicle, insufficient solder vertical fill of PTH or soldering defects caused by insufficient heat

Cause of defects

The high temperature accelerates oxidation of solder and workpiece surface. It degrades solder wettability.
If workpiece is not heated enough for soldering, for solder to melt and spread, it causes soldering defects.

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Improvement by antioxidant or preheating effect

The use of nitrogen gas in soldering improves solderability because it prevents soldering joint from oxidation and gives preheating effect to workpiece.

Improvement of wettability

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Comment

Solder flows to the higher temperature side as a characteristic.
Solder flows evenly and smoothly over the copper board when temperature of workpiece reaches the melting point of solder. The workpiece that preheated with heated N₂ gas gets warmed faster than the workpiece without preheating.
Once workpiece is heated enough, solder starts to spread on it. The use of N2 System improves solderability by its preheating effect and antioxidant effect.

The followings are considered as causes of soldering defects; improper movement of soldering iron, inappropriate amount of solder, improper speed to feed solder and oxidation of soldering tip.

More expected effects

If solderability improves;

Soldering with no clean flux (mildly activated flux) is achievable.
N₂ System solves the problem of soldering with lead-free solder, of which solderability is poor, and no clean flux (mildly activated flux).

Relation between mildly activated flux and N₂ System

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As soldering without cleaning process becomes more general, the use of mildly activated flux that leaves less residue has become more general too.

Flux residue can cause corrosion on soldering points and it can cause product failure. Therefore it is important to clean flux residue. However, the use of some cleaning agent has been restricted due to the consideration of environmental issues (e.g. Fluorine regulation). Eventually the use of no clean flux has become more general.

ProblemSolderability with mildly activated flux is poor due to its low activity.

Meanwhile, soldering with lead-free solder has become more general.

Acid rain melts lead (Pb) contained in soldering materials of waste electronic components and the melted lead (Pb) contaminates groundwater. To prevent this, the use of lead-free solder has been promoted.

ProblemWettability of lead free solder is poor, so that solderability of lead free soldering with the use of mildly activated flux becomes very poor.

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N₂ System improves solderability in soldering with lead-free solder and mildly activated flux.

N₂ System solves the problems of mildly activated flux by its antioxidant effect and preheating effect.

Functions of flux

Cleaning:
Removes oxides and stains on metal surface for solder to spread well.
Preventing re-oxidation:
Prevents solder joints from re-oxidation by covering their surface.
Lowering surface tension:
Lowers surface tension of solder to spread well.

N₂ System works well for multilayered P.W.B.
N₂ System helps improve solderability on multilayered P.W.B. which is difficult to solder because of its high heat capacity.

B:　In case of damaged components (capacitor, LED, etc.) by rapid heating

Cause of defects

If components (e.g. IC chip) is heated rapidly with soldering iron, it can be damaged.

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Improvement by preheating effect

Preheating effect helps lower set temperature without degradation of solderability and that results in reducing thermal load to heat-sensitive components.

About setting temperature

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Preheating effect of N₂ System helps lower set temperature without degradation of solderability and that results in reducing thermal load to heat-sensitive components.
Look at the following graphs showing the difference of soldering time with / without nitrogen gas in case of HAKKO FX-951 and HAKKO FX-838.

Thermal recovery comparison graph of HAKKO FX-838 and HAKKO FX-951

HAKKO FX-951

Test method:	Measure the time until the workpiece reached to 250℃ at 5 points; Setting temperature is 320℃ with nitrogen gas and 340℃ without nitrogen gas.
Board:	FR-1 (Paper phenol copper), single-sided
Component:	Connector
Tip shape:	T12-D24 without nitrogen gas T13-D24 with nitrogen gas
Setting temperature:	340℃ without nitrogen gas　320℃ with nitrogen gas
Solder:	Lead-free solder (Sn-3Ag-0.5Cu) ø0.5

Please refer to above values, which vary depending on soldering condition.

HAKKO FX-838

Test method:	Measure the time until the workpiece reached to 250℃ at 5-points; Setting temperature is 320℃ with nitrogen gas and 340ºC without nitrogen gas.
Board:	FR-1 (Paper phenol copper), single-sided
Component:	Connector
Tip shape:	T20-D24 without nitrogen gas T20-D24 with nitrogen gas
Setting temperature:	340℃ without nitrogen gas　320℃ with nitrogen gas
Solder:	Lead-free solder (Sn-3Ag-0.5Cu) ø0.5

*Please refer to above values, which vary depending on soldering condition.