INTRODUCTION:
A significant breakthrough for manufacturers of the popular PC/104 bus was heralded at the 997 at the WESCON Exposition in Silicon Valley when. Zephyrtronics, long recognized as the pioneer in bottom side convective heating systems, showcased for the first time a remarkable new product that they called an AirFountain® with an initial focus on addressing the long-time troubles of reflowing the new PC/104 bus connectors to PCB's.

This patented invention, the ZT-6 AirFountain® hot air reflow system, turned out to be a multi-tasking performer, not just limited to PC/104 applications, but also for many off-line, secondary operations which many times include soldering through-hole connectors, pre-heating of giant PCB's and ceramic flight boards, and for desoldering and removing of multi-pin connectors and pin grid arrays.

And the product  quickly proved to be a cleaner and more consistent alternative to messy and awkward traditional solder fountain. Hence, the AirFountain®.

The ZT-6-MIL AirFountain® Multi-Functions as Not Only Super Bottom-Side Pre-heating Device, But Also as a Benchtop Hot Air Selective Soldering & DeSoldering Unit. It Excels at Soldering Hundreds of Connector Pins Simultaneously and Is Ideal for All PC/104 PCB Processing at the Bench!

What Is An AirFountain and How Does It Work?: The AirFountain® provides simultaneous reflow to the connector/pad interface through its ESD-safe heated air supply where the temperature is tightly maintained by a digital microprocessor control. The heated air is propelled from the AirFountain® below the PCB and is targeted directly to the leads of the connector making clean, non-contact reflow quick and repeatable.

Unlike messy solder fountains where heat up times can be long and where the solder pots can be messy, prone to spills, and such, the AirFountain® ramps up to temperature right away, requires no solder ingots, and is completely portable due to its internal air supply. Where gold tailed connectors could not be dipped into solder fountains or solder pots, the AirFountain® has no such limitations.

And because the AirFountain® is lightweight and portable, it can be readily used at the production floor, a test lab, an engineer's desk, or in the field where rework and repair may be needed. Further, where even the most careful hand soldering of the 104 gold pins still has the potential for solder wicking up the gold tails, again, the AirFountain® has no such limitations.

Finally, the AirFountain® makes connector removal easier than before. The simultaneous reflow of all leads means that a technician can simply extract the connector right out of the substrate without fear of lifting pads. Indeed, a 104 pin connector, typical of the PC/104 bus, can be completely reflowed after insertion into the board and/or reflowed for extraction/removal.

Different sizes and configurations of connectors such as the popular PC/104 Plus are easily handled with the introduction of affordable AirFountain® which target the heated air directly to the connector's leads for reflow.

The AirFountain® Simultaneously Reflows All 104 Pins of the PC/104 Bus.  Terrific for High Volume Production or With Extraction/Removal as Shown

Problems With Current Off-Line Connector Assembly for the PC/104 Bus:  Any off line assembly of the PC/104 bus connectors to the module PCB has presented several challenges in the past for manufacturers. Some of the problems are noted below.

First, the noble metal finish (typically gold) on both the plug and the receptacle could not be compromised with any solder deposits on the mating portion of the connector tails. Therefore, use of wave soldering, solder pots or solder fountains are out of the question for assembly.

Second, the use of solder preformed donuts presents a host of new problems to the manufacturer. The principal disadvantages are additional raw material costs, additional labor to install the loose donuts on each connector contact tail and retaining the donut onto the contact tail so that they do not fall off during normal handling.

Ending the Inefficient Hand Soldering of Connectors in Secondary Operations:  Perhaps the most obvious drawback for off-line processing the PC/104 has been the resorting to hand soldering of the 104 pin connector to the board. When the J1 and J2 connectors are stacked side by side in 16 bit modules this creates 4 parallel rows of contacts to be hand soldered.

The tight spacing between the rows and length of the contacts (.480") exacerbates the hand soldering problems making the utility of a soldering iron difficult. (Note: to see a color, step-by-step pictorial of how the AirFountain® works for soldering and de-soldering connectors, click this link). Labor intensive, operator sensitive and time consuming, the hand soldering operation reduces the potentially high volume processing of the PC/104 down to the bottleneck and limiting factor of operators soldering 104 pins by hand. And truth be told, hand soldering the gold tails inevitably result in high scrap rates with solder wicking onto the gold tails, bent leads, and more.
 

The Synergy of the AirFountain®, A Solder Bearing Connector & the PC/104 Bus:
Synchronous reflow of all 104 pins for the PC/104 bus (or similar applications such as the PC/104 Plus) can now be made quickly per assembly and, best of all, yielding high quality, eutectic solder joints with fillets on both top and bottom far exceeding the most stringent requirements of IPC Class 3. Indeed, the barrel fill from the AirFountain® is strikingly superior to pins hand soldered when a visual, comparative inspection is made.

The entire process is described simply as:

1)  Taking the solder bearing PC/104 connector,
2)  Inserting it into the board, and
3)  Placing the assembly onto the AirFountain®.

The reflow of all 104 pins is made rapidly and another board assembly is ready for processing. In other words, high volume production of PCB assemblies can continue at high volume rates even when off-line reflow is required for through hole connectors.