PCB Rework Pre-heater     Bottom-Side Preheating     Pre-heat for Heavy Ground Planes      Lead-Free PreHeat Rework

1996 "Vision Award" Awarded to Zephyrtronics for
the AirBath™
 "Best New Product of the Year"

The AirBath is Spotlighted in Ray Prasad'sText
"Surface Mount Technology"

"Innovative...simpler, safer way to remove and repair sensitive devices" The Editorial Staff, SMT MAGAZINE

The Zephyrtronics' AirBath “bathes the circuit board in warm air to reduce thermal stresses to the board and components.”-- NASA Report Jan '04

No One Knows More About Preheating Than Zephyrtronics!  The pioneer and world-leader in bottom-side preheating for PCB's introduces our largest, most powerful model yet of our  world-famous AirBath™ Pre-heating Systems. The ZT-1-MGS-DPU Mega-Grid AirBath™ features a full 32-square inch (220  sq. cm) pre-heating grid with 1,500 watts of power and 50 CFM (1,415  liters/minute) of air supply of pre-heating and cooling.

Developed by Zephyrtronics at the specific request of NASA, our Mega-Grid™ AirBath is now available to all our customers with PCB's over 18" (45cm) in size or with high copper content, heat-sinks, large ground or back planes. What a workhorse!

The patented protected technology within the Mega-Grid™ AirBath™ presents the most effective solution for PCB pre-heating during prototyping or rework at the bench for thru-hole and surface mount technology including Ball Grid Arrays. Far more than just a preheater, this is a Zephyrtronics AirBath™.

Approached by NASA in 2004, Zephyrtronics Developed Our "MegaGrid™ AirBath For Their Space/Military Applications. The MegaGrid™ is Now Available to All Our Customers.

Preheat Power: Our Mega-Grid™ AirBath with its powerful 50 CFM (1,415 liters/minute) of air supply and its 6.3" x 5" (16cm x 13cm) enormous heating grid delivers its forced-convection preheating power as needed for those "boards from hell" -- as many engineers like to say.  Beware of imitative pre-heaters with less than 13CFM (360 liters/minute) that crudely attempt to compensate for their lack of preheat air volume with higher temp settings. Remember: the glass transition of a FR-4 PCB is only 170°C. You don't want higher preheat temps, you want a higher volume of safe preheated (100°C to 170°C) air applied to your PCB's.

Loaded With Premium Features: The Mega-Grid™ gets into all the nooks and crannies of the PCB assembly where hot plates and IR pre-heaters can't go (more below).  It is ESD-safe; features  indicator lights (blue: cooling; red: preheating); it is self-contained with an internal air supply (no hookups); all inside a  durable, steel housing for industrial use and long production life.

Critical Thermal Ramping: The Mega-Grid™ AirBath has industry standard, built-in temperature ramping at 2° to 4°C per second preventing thermal shock to sensitive chips, ceramic caps and glass diodes. The ramp is "built in" by design into every Zephyrtronics AirBath™ Preheating System.

The Many Benefits of Preheating Your PCB: The benefits from preheating are multiple and compounding. 1.) Preheating or "soaking" the assembly prior to initiating reflow helps to activate the flux, removing oxides and surface films from the leads and pads to be soldered, thereby enhancing the wetting process and solder joint quality.  2.) Preheating the board permits lower soldering reflow temperatures.  3.) Preheating reduces the final "dwell time" during the final reflow stage.  4.) Preheating reduces thermal stresses to the PCB substrate and its components when localized reflow is made with soldering irons, de-soldering tools and hot air systems. 5.) Preheating provides the thermal boost needed when working with RoHS lead-free solders without damaging the work!

Digital Illuminated Temp Display & Control: MIL-Spec compliant, the Mega-Grid™ has closed-loop, electronic feedback-sensing control and variable temperature selection with a lighted digital temperature display.  A convenient microprocessor control permits variable temperature selection with an easy-to-use "set/read" digital display function.

For Thru-Hole, SMT & BGA Preheating Tasks: The Mega-Grid™ AirBath is ideal for all PCB challenges from low-volume production runs, prototyping during design or during rework with all component packages such as BGA, CSP, QFP, QFN, TSOP, PLCC, SOIC, SOL, LCC, Flip Chip and Glob Top components. And it easily handles all substrates including FR-4, polyimide, composites, flex circuits and ceramic boards.

Comparing The 4 Methods of Preheating:

Pre-heating PCB assemblies falls into four categories: Use of hot plates, use of ovens, IR systems, and the use of forced convection (warm air) under the PCB: While any preheating of your PCB prior to solder reflow is certainly better than none, an objective analysis of the various methods of preheating quickly reveals that all preheating methods are not equally effective or beneficial:

1.) The Oven: The use of an oven to pre-heat the substrate before reworking and initiating solder reflow for either removal and/or replacement of components can yield the most uniform temperature profile as it warms both the top and bottom of the PCB assembly as ovens also do in high volume production equipment such as conveyor ovens and wave solder machines. It's just a little problematic to crawl inside an oven with your PCB to preheat while you perform selective soldering or desoldering tasks on one side of the board. Of course, one can preheat in an oven and then race with it in your high-gloved hands back to the bench, but it's hardly a solution either.

2.) The Hot Plate: The obvious limitation to the hot plate is that not all PCB assemblies are single sided. In fact, in today's world of hybrid and mixed technologies, the PCB that is entirely flat or plane on one side is an exotic and rare creature indeed. PCB's typically can carry heat sinks, connectors, jumpers and transformers on both sides of the substrate. These uneven surfaces on the board present an indirect path of heat conduction from the hot plate to the board assembly.

3.) The IR Preheater: There are many drawbacks to infrared which is why it has really never completely caught on.  Some of drawbacks which have been enumerated in articles in SMT Magazine, Circuits Assembly and in white papers at electronic conventions are the difficulty in ramping temps (some are better than others); shadowing caused by high profile components on PCB's; and if the IR preheat grid is very large it can make working on small PCB's very uncomfortable for the technician (this is a very common complaint). Still another great disadvantage to IR preheaters is that they can not ever truly be "temperature controlled" without the technician having to always pre-assemble an external thermocouple into every board before working on it. And that's a continuous hassle and headache replete with quality pitfalls and problems with inconsistent results. There are more, but these are some of the key setbacks.

The Picture Tells the Story:
A Comparison of Two Popular PCB Preheating Methods

NASA & JPL: 'IR Preheaters Are Risky': Addressing the critical preheating process during rework of plastic and other heat sensitive components in their 49-page published report, two JPL engineers, Dr. Rajenshuni Ramesham and Dr. R. David Gerke, wrote "Hot plates and infrared preheaters are not recommended for this type of rework. The reason that they should not be used is that the thermal reaction times, energy transfer rates and efficiency are never consistent. However, they can be used for large metal and ground-plane boards in limited applications, e.g., where the size of the board matches that of the preheater in area." Continuing and also citing the late William Scheu, the authors pointed out the superiority of preheating by bottom-side forced convection systems. Moreover, the NASA Survey by JPL spotlighted still more of the deficiencies of IR preheating devices: "They have little capacity to ramp and soak to perform properly engineered repair scenarios or to support the creation and application of complicated thermal profiles. They also are limited in their ability to preheat beyond the physical dimensions of the heating surface. Hot-air preheating can be ramped, soaked and, on some systems, synchronized with the reflow process, permitting duplication of the actual profile used in manufacturing the assemblies. BGAs and photoelectrical parts are sensitive to higher temperatures and any attempt to preheat with marginally controllable sources is risky." ---' NASA & JPL: Survey of Rework Methods & Equipment for Various Packaging Technologies." -- August 2005.

4.) Superior, Forced Convection Preheat, The AirBath™:  The market has long spoken with regards to the distinct advantages and superiority of a warm air bath in the pre-heating process. Forced convection completely disregards the topography (or bottomography) of the PCB, allowing immediate, direct access of the warm air into all of the nooks and crannies of the PCB assembly. And much like the newer, popular forced convection commercial ovens, the circulating warmed air is far more effective than static warm air.