Nexus_en - 第9页
Formic acid tank (bubbler) T o achieve a stable, reliable, flux-free soldering pr ocess, the iner t carrier gas (N 2 ) is enriched with formic acid (HCOOH) and transferred int o the process chamber . So that the “ satura…
Inert gases and forming gas
Nitrogen (N
2
) is typically used to protect against
oxidation. In combination with 5 % hydrogen, the forming gas
is also used for reducing oxides; no special safeguards are
necessary within this mixing ratio.
Forming gases with a hydrogen content from 5 % to 100 %
need necessarily appropriate safeguards and are used only at
280 °C or higher. Depending on the process temperature, the
use of formic acid can be benecial.
Activation (Gas)
Investment Wetting
Nitrogen N
2
Forming gas N
2
/H
2
(95 %/5 %)
Hydrogen H
2
100 %
Formid acid HCOOH
N
2
N
2
/H
2
Various media
for a wide range of requirements and demands
Depending on the process temperature and the desired oxide freedom, the use of different process media is possible.
Formic acid tank (bubbler)
To achieve a stable, reliable, flux-free soldering process, the inert carrier gas (N
2
) is enriched with formic acid (HCOOH) and
transferred into the process chamber. So that the “saturation” of the carrier gas with formic acid remains constant, it is neces-
sary to keep the parameters constant while the liquid formic acid is flowing through. These include the flow velocity, flow rate,
temperature and the lling capacity of the formic acid tank (bubbler). Thanks to today’s control engineering, the nitrogen flow
rate can be monitored easily and reliably. Unlike the ll level of formic acid in conventional bubbler solutions which must be
manually relled with acid – taking into account the protective measures for employees – and here are subject to a greater
fluctuation in the lling capacity. This is not the case for this new generation of bubblers which monitor and readjusts the ll
level. This allows a stable process, and also increases the safety of employees, because original containers (standard 10 l)
with formic acid can be inserted into the housing of the bubbler without decanting. To make the device even safer, the housing
is monitored and equipped with its own suction system.
The removal of the oxides on metals with formic acid is performed using a two-step process; the schematic sequence of
this process can be seen in the following diagram. During the rst step, so-called formates of the metal are formed and the
formates are decomposed (Cu) or vaporised (SnO, SnO
2
) at approx. 200 °C. The H+ formed during the second step supports
oxide removal as well as the molten solder from the melting temperature in the reductive environment. This allows for a highly
wettable surface on copper and other metals. The application is suitable from process temperatures upwards of 200 °C.
controlled chamber pressure with nitrogen atmosphere
pressure level constant
formic acid tank (bubbler)
pump
proportional valve
or mass ow controller
HCOOH
N2
0 °C
150 °C
200 °C
SnO
2
+ 2 H - COOH Sn + CO
2
+ H
2
O
SnO
+ H - COOH Sn + CO
2
+ H
2
O + H
2
M - COOH
2
M + 2CO
2
+ H
2
MO + 2H - COOH M - (COOH)
2
+ H
2
O
Data and facts:
Detail information on the Nexus
Software
Vacuum process
Datas
Process chamber
Heating plate
› Heating/cooling plate programmable with closed loop control
› Equipped with an integrated thermocouple to check the temperature prole of the heating plate
› Temperature uniformity on the heating plate within +/-2 K
› Heating/cooling plate with a usable area of 500 mm x 500 mm
› Max. operating temperature 400 °C
*
, optional up to 450 °C
› Heating rate max. 150 K/min
*
, cooling rate max. 180 K/min
*
› USB port and Ethernet port for connectivity and remote control
› Windows 7 for HMI and B&R PLC for machine control
› Up to 100 steps per recipe
› Number of recipes is not limited
› Traceability and MES connectivity available
› Each step can be lled in with a predetermined pressure, temperature, heating/cooling rate or holdinge time.
Furthermore it is possible to work in each step alternatively with nitrogen, forming gas and formic acid.
› Graphic display of temperature values and pressures on the monitor for process control
› Programmable times per step range from 1 s to 1 hour
› Chamber with viewing window for camera (available an an option)
› Operation from front side
› Residual oxygen analyzer
WEIGHT
680 kg
ELECTRICAL CONNECTION
3 x 400V +/-5 % 50Hz TN-C-S
› Vacuum pump alternatively up to 2 mbar or 0,1 mbar
› Pressure sensor readout recorded with internal software
*
related to contact plate
COOLING WATER
Cooling system for connection to an open water cooling system or
domestic water supply 10-15 SLM cooling water flow
DIMENSION
Length 1617 mm, Width 1194 mm, Height 1336 mm