Mar 11, 2003 The technique uses DEK's award-winning Proflow Direkt Imaging system to achieve excellent fill results with aspect ratios of up to 8:1.
The Via Fill system is highly repeatable and results in a throughput of over five times faster than the traditional squeegee-based fill process, as well as greater accuracy.
Cost savings resulting from increased utilisation of manpower and considerably reduced wastage are also realised, while process control is significantly enhanced.
The ProFlow-based process solves problems such as insufficient fill, voiding, poor throughput and excessive handling of the product associated with conventional methods.
The fully enclosed ProFlow head is used in conjunction with a sheet of blotting paper underneath the substrate and on top of the tooling block to fill vias in just two print passes, with a paste pressure of 2.5bar and a print speed of 25mm/s.
In addition, the print material has been shown to have a life of over three months in the transfer head.
Traditional manual or squeegee-based systems are not only far less clean and operator-friendly, but they typically take multiple passes to push material into vias.
They can also use a vacuum table to pull material through, resulting in both voids and inadequate deposition.
The ProFlow Via Fill process was developed in conjunction with a major material supplier and two customers.
The aspect ratio of board thickness to hole diameter is typically a challenging problem, although superb results have been achieved with ratios of up to 8:1.
As a result of the increasing demands of higher component and PCB densities, DEK is currently developing the system to cope with aspect ratios as high as 13:1.
