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Vapor Phase Soldering is also known as Condensation Soldering.

In the first process step the cold PCB is delivered to a chamber in which there is vapor evaporated from a special liquid (medium) for this process – perfluoropolyether (PFPE).

The liquid is chemically inert and with density almost twice higher than the water. Due to the temperature difference between the PCB and the vapor, condensation on both sides of the PCB starts immediately. The condensed vapor forms a thin film completely over the PCB.
 

The high surface tension of the liquid used allows to cover well every critical gap on the PCB such as the space under BGAs, closely placed or odd shaped components, etc.
Due to the high density of the vapor, the liquid film on the PCB pushes away the Oxygen. Therefore the soldering process takes place in Oxygen free environment.
As the film conducts heat quite well, the thermal energy is transmitted to the PCB homogeneously.
 

The liquid is heated by electric heaters. Once the boiling point has been reached, the liquid does not increase further in temperature. Any further energy supplied will be used to produce more vapor (enthalpy of evaporation).

The amount of liquid condensing on the PCB depends on the amount of vapor in the chamber.  If you supply more heat from the heaters, the amount of vapor increases. By controlling the heat transferred from the heaters to the liquid in the chamber, the amount of condensed liquid on the PCB can be changed. This allows to change the rate of heating the PCB after entering in the chamber.

The condensation of vapor stops when the PCB reaches the temperature of the vapor. Therefore the boiling point of the liquid defines the maximum temperature to which the PCB is exposed. For lead free soldering we recommend to use a liquid with 230oC boiling point and for Sn/Pb soldering - 200oC. Other liquids are available from Asscon with boiling point from 160oC to 260oC. The special liquid for vapor phase soldering is available from several suppliers, not only from Asscon.

When the solder paste is completely reflowed, the PCB is removed from the chamber.  After the PCB leaves the vapor zone, the remaining condensed fluid on the PCB evaporates, due to the residual heat of the board.

In the last process step the soldered and dry PCB is cooled in a cooling zone.

Many test proved that on one and the same PCB the amount of voids after vapor phase soldering is smaller compared to convection reflow soldering. To reduce further the amount of voids Asscon developed a vacuum section which can be added to the high end vapor phase ovens. The picture below on the right shows the reduction of voids using such section on the same component under the same conditions, compared to the standard vapor phase soldering (the picture on the left).

ABOUT ASSCON

The company was established in 1995 by several people who were involved in the design and manufacture of vapor phase ovens of the earlier generation (1980’s). Taking into consideration the demands of the Lead Free process, the latest developments of the liquids suitable for vapor phase soldering and the limitations of the modern forced convection ovens, Asscon designed first class reliable equipment performing with excellent repeatability and working with very low running costs.

The company is located near Munich where all ovens are manufactured, tested and shipped to the final destination.

The key advantages of  Asscon vapor phase ovens are:

1. soldering in O2 free environment (eliminates the need to use N2)
2. guaranteed control of the max. temperature in the oven due to the physical properties of the liquid used – typically 230oC for Lead Free and 200oC for Sn/Pb boards
3. better heat transfer to the PCB due to the use of liquid for that and not air and N2. This reflects in considerable reduction of electrical power consumption. The maximum power consumption of the smallest oven (Quicky 300) is 2 kW, while the average consumption during soldering is 1 kW. The maximum power consumption of the large inline oven (VP 2000) is 12 kW, while the average consumption during soldering is 6 kW.
4. flexible and easy control of the PCB temperature until reaching the reflow values
5. reduction of the voids in the solder joints. For further decreasing the amount of voids, a vacuum section can be added to the vapor phase systems
6. most complex and demanding PCB’s can be soldered with ovens that cost less compared to the forced convection ovens
7. the number of soldering defects is usually smaller

Due to the above reasons many leading manufacturers as Siemens, Bosch, Alcatel, Daimler Chrysler, Motorola, Nokia, EADS, Semicron, Alenia, EPCOS, Matra, Marconi Aerospace and others are already using the Asscon ovens. In many other contract manufacturers such as Flextronics, Hella and others the Asscon vapor phase ovens are used for prototypes or for short series of complex or difficult to solder PCBs.

Product Range
	For laboratories and prototyping. Easy operation. Immediately operational.		Quicky300: - PCB format: max. 300 x 300 mm - Cooling via distilled water - Manual conveyor
	For laboratories and prototyping. Easy operation. Immediately operational.		Quicky450: - PCB format: max. 450 x 450 mm - Closed cooling system - Automatic operation process sequence
	For laboratories, prototyping, close-to-production process qualifications and very small series. Space saving, all-purpose soldering system. Optional up­grade: closed external cooling system and medium filtration system.		VP800: - PCB format: max. 400 x 400 mm - Automatic operation process sequence
	For small and medium sized series. Standard unit with universal work-piece carrier loading/unloading station, automatic filtration system and integrated exhaust system. Optional up­grade: water cooling system with compressor.		VP1000: Standard sizes PCB format:             - VP1000·44 :  400 x 400 mm             - VP1000·64:      600 x 400 mm                          -VP1000·66:    600 x 600 mm
	For in-line production of medium-volume-series. Standard unit with center support, electric width adjustment and permanent filtration system. Optional up­grade: closed internal cooling system, collection of operational data and diagnos­tic module via modem.		VP3000: - PCB size: max. 600 x 500 mm - Pin and chain conveyor with edge support
	For in-line production of large series. Equipped with SMEMA interface, conveyor width adjustment, center support and per­manent filtration system as a standard. Optional upgrade: closed internal cooling system, collection of operational data and diagnostic module via modem.		VP2000: - PCB size: 565x 500 mm - Optional PCB size: 1000 x 500 mm - Pin and chain conveyor with edge support
	For small and medium sized series . Standard unit with universal work-piece carrier loading/unloading station, vacuum process chamber, automatic filtration system and integrated exhaust system. Optional upgrade: water cooling system with compressor.		VP6000·vacuum: - PCB size: 400 x 600 mm - In-line version with SMEMA interface available
	For in-line production of large series. Equipped with SMEMA interface, work piece carrier transportation and permanent filtration system as a standard. Optional upgrade: closed internal cooling system, collection of operational data, diagnostic module via modem and PCB-transportation with electrical width adjustment.		VP 2000·vacuum: - PCB size: 450 x 400 mm - Optional PCB size: 800 x 400 mm - Pin and chain conveyor with edge support