There's nothing like the patented ZT-1 Mega-Grid™ AirBath™ ("the mother of all pre-heaters") with its 32-square inch (220  sq. cm) pre-heating grid and 1,500 watts of power and 50 CFM (1,415  liters/minute) of pre-heating volume and cooling. The forced convection from the AirBath™ preheats PCB's up to 18" x 18" (45cm x 45cm) in size. Unlike inferior IR systems, forced convection bathes the entire PCB with preheat.

Forget About IR Systems with their many drawbacks that only preheat the area directly above the IR grid.  AirBaths™ have no such limitations!

Developed by Zephyrtronics at the specific request of NASA over a decade ago, our ZT-1 Mega-Grid™ is available for your largest PCB's and those with high copper content, heat-sinks, large ground or back planes. What a workhorse this is!

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 activates flux, removing oxides and surface films from leads and pads to be soldered, thereby enhancing the wetting process and solder joint quality.  2.) Preheating the board permits lower soldering temperatures.  3.) Preheating reduces the final "dwell time" during the final reflow stage.  4.) Preheating reduces thermal stress to the PC substrate and its components when localized reflow is made with soldering irons, de-soldering tools or hot air systems. 5.) Preheating provides the thermal boost needed when working with RoHS lead-free solders without damaging the work!

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.

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. Microprocessor control permits variable temperature selection with an easy-to-use "set/read" digital display function. This is the greatest pre-heater on earth.

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 for all SMD packages such as BGA, CSP, QFP, QFN, TSOP, PLCC, SOIC, SOL, LCC, Flip Chip and Glob Top components. Still, the AirBath  is not limited to only SMD devices: Don't overlook the superb benefit the AirBath  preheating boost brings to your tough through-hole (PTH) soldering and de-soldering tasks! Plus, it easily handles all substrates including FR-4, polyimide, composites, flex circuits and ceramic boards.

PostCooling™ your PCB at the bench after solder reflow was first introduced to the market by Zephyrtronics nearly 20 years ago. Of course, today anyone knowledgeable with processing BGA's at the bench knows how critical post cooling is to the process so as to form strong solder columns between the pad and the chip so they will not "open" up later. This is very important. Of course, quick cooling has been proven over and again to produce stronger, more resilient solder joints even with hand soldering. It's no wonder that all high-volume PCB conveyor ovens have a final "cool down" feature.

Your Lead-Free Solution: Working with lead-free, RoHS solder alloys --- all have higher melting points --- makes preheat essential to PCB work at a bench. Don't raise temps higher on your soldering irons, desoldering tools, hot air tools or thermal tweezers! A brief preheat below the PCB permits soldering/ desoldering at lower temps.

The RoHS Lead-Free Solder Mandate: Europe (and Japan) no longer permit the use of traditional tin/lead solders. Learn more about the European Lead-Free Mandate & Preheating. AirBath™ preheaters are your RoHS solution making lead-free soldering a breeze.

  Comparing the Four Methods of Preheating

Preheating PCB assemblies falls into four categories: 1.) hot plates, 2.) ovens, 3.)  IR systems, and 4.) forced convection (warm air) under a PCB: The short video at the right breaks down these four methods with comparative demonstrations. While any PCB preheat prior to soldering is better than none, an objective analysis of the various methods of preheating reveals that all preheating methods are not equally effective or beneficial:

1.) Ovens: Using ovens to preheat before rework and soldering 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 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 with an oven, and then rush the PCB back to your bench, but it's hardly practical solution.

Hundreds of Zephyrtronics AirBaths™ Utilized to Build the International Space Station (ISS)

39-Page Rework Guide
by NASA with Zephyrtronics AirBaths™

Zephyrtronics AirBaths™ Used on the Mars Rover & Phoenix Programs.
Photo Credit: NASA

2.) IR: There are many drawbacks with infrared and why it really never completely caught on.  Some of the drawbacks (enumerated in articles and white papers) are the difficulty in ramping temps, darker surfaces heating more than lighter ones ('albedo' effect), shadowing caused by high profile devices on PCB's. IR preheaters can warp PCB's and some chips require IR shielding with aluminum foil! If an IR preheater is very large, working on small PCB's can be very uncomfortable for techs (a common complaint).

Another quality disadvantage of IR preheaters is they are not "temperature controlled" without taping an external thermocouple onto each PCB before working on it...a hassle/headache for techs and filled with quality pitfalls, and inconsistent results. There are more drawbacks, but these are some of the worst.

NASA & JPL: 'IR Preheaters Are Risky': Addressing the preheating process for heat sensitive chips in a 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."

Citing the late William Scheu, the authors point to the superiority of bottom-side preheating with forced convection systems. The JPL/NASA Survey 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" Aug.'05

  Post-Cooling™ Feature Built Into The AirBaths™ 

Another real advantage of the AirBath™ is that with by flipping a switch the unit transforms into a post-cooler™ cooling down your PCB, components and your solder joints. Post-Cooling™ is essential to soldering of BGA's because hot air nozzles must not be lifted from above the BGA until all the balled joints have cooled so as not to cause unwanted bridging. It's important to point out the obvious: hot plates, static ovens and IR plates do not provide the critical post-cooling™ feature standard on every Zephyrtronics AirBath™.

Our AirBaths™ cool BGA's in 8 seconds permitting the hot air nozzle to be lifted without fear of bridging. Without post-cooling™ a tech must wait for the ball/pad interface to solidify completely before lifting the nozzle to inspect.

The PostCooling™ feature remedies this problem allowing rapid lifting of a hot air nozzle from the BGA after soldering.  Again, our engineers introduced the concept of post-cooling™ to the benchtop clear back in 1994.