Vapor Phase Reflow for complex SMT boards
Gemini Tec use the very latest processing technology available to manufacture customer PCBA products. We operate with two Asscon vapor phase reflow ovens, providing customers with seamless PCBA processing from early prototype through to batch production. Gemini Tec are the first UK CEM to operate the latest in-line vapor phase reflow oven, manufactured by ASSCON of Germany.
Vapor phase soldering has slowly become the best method to achieve the optimum soldering quality. The development of the in-line process has now reached the suitable point to balance with a fast SMT line. The investment in hardware is vastly more than a standard convection oven, so it has yet to become mainstream, despite many 'below the line' benefits.
How does vapor phase work & why is best suited to high technology PCBA products?
Vapor phase is centred around the use of Galden contained within a 'inert atmosphere'. This process is also known as condensation soldering. The process can also be used in conjunction with a applied vacuum, mainly to achieve void free soldering on highly complex SMT component parts.
Within the oven chambers Galden (a chemically inert fluid) is used as a the heat transfer medium. The fluid is both a non-corrosive and electrically non-conductive and can only reach a set maximum temperature when in use.
Within the oven process the fluid starts to evaporate, a layer vapor and condensing fluid covers the PCBA creating an inert and oxygen-free atmosphere. The vapor’s weight is greater than the surrounding air and forms a protective gas atmosphere and as soon as the PCBA is immersed into the vapor zone, the vapor condenses on the PCBA and transfers the heat for the reflow.
As the heat transfer is linear across the entire assembly the PCBA will never overheat, irrespective of the time the PCBA sits within the vapor (the temperature can never exceed the maximum vapor temperature) Unlike convection ovens each portion of the process (i.e. ramp/dwell) can be configured to suit any variable required, without applying excessive heat.
As a result, the solder process can be reliably reproduced and delivers a repeatable process. The vapor phase soldering process achieves the optimum results for a wide range of assemblies, from flexible to multi-layer substrates without ever overheating the components passed their recommended temperature.
The need to continually create and manage various thermal profiles for each PCBA produced, has now been eroded, due to the even heat distribution across any type of PCBA.
See more at our suppliers site: https://www.asscon.de/e/index.html
Advanced Capability with Vacuum Processing Technology
In the multi-vacuum soldering process, assemblies are subjected to several vacuum applications with the option of applying vacuum processes both before and during the melting of the solder paste. Applying vacuum processes before the liquidous temperature is reached is particularly useful for removing any voids encapsulated and caused by printing or pick & place processes.
With lead free solders void formation risk is higher, due to the higher process temperatures. The patented technology used on ASSCON vapor phase removes voids (formed after soldering) from the liquid soldering location.
Automatic Solder Break (ASB)
During the soldering process, the solder melting is recognised by an automatic recognition of the melting point which avoids effectively the formation of cold soldering locations. The usual engineering of soldering profiles is removed allowing us to produce complex products, with reduced lead times on fast delivery prototypes.
A typical complex PCB assembly produced at Gemini Tec using 0.4 mm pitch/12 mm sq. device: The process used to build this product combines the use solder jet printing, for the application of the solder deposit onto its 0.23 mm pads, placement of device using our Mycronic SX200 chip placement SMT line, followed by vapor phase reflow. Our jet printing capability includes AOI [inspection] of all the deposits, prior to placement, with vapour phase reflow ensuring the PCBA is subjected to correct thermal heat, avoiding interconnection problems, such as short and opens. Vacuum processing capability allows the balls to be free of voids.
Gemini Tec support a wide range of customers and applications from prototype to medium volume production, our investment in processing technology, allows us to support complex and demanding PCBA products where reliability and conformance is essential.
Contact us to talk about your requirements in more detail. +44 (0) 1252 333 444
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