Just a few decades ago, commercial consumer products were normally cleaned in an inline (conveyorized) defluxing machine operating with nothing more than water. The most common flux was water soluble (OA), eliminating the need for a chemical additive to remove the flux. Military and other high-reliability assemblies were soldered using rosin-based fluxes and were most often cleaned using a batch process vapor degreaser. In short, commercial defluxing processes utilized inline cleaning technology while high reliability applications were cleaned using batch-format technology.

After the implementation of the ban on chlorofluorocarbons (CFCs) in 1987, no-clean fluxes emerged in the marketplace. Most commercial manufacturers converted their assembly processes to a no-clean flux, but the high reliability industry (military, aerospace, medical) continue to remove the flux residues from their assemblies. There are various reasons for defluxing, all relating to product reliability. Assemblies with no flux are inherently more reliable than their flux-residued counterparts.

The EMPF demonstration factory has received the new Trident series batch defluxer from Aqueous Technologies of Rancho Cucamonga, California. Early batch defluxing equipment more closely resembled household dishwashers than industrial defluxing machines. After the CFC ban and subsequent decline of commercial defluxing, manufacturers of inline defluxing equipment focused their sights on the high reliability market. Inline defluxing systems, while capable of removing flux residues, were large, loud, expensive, and consumed high quantities of electricity, water, and chemicals. These were not significant issues with commercial assemblers given the high volume of products produced. But for a low volume, high reliability application, a less expensive batch defluxing system was needed.

Over the past two decades, manufacturers of batch format defluxing systems have not only improved their cleanliness results, but also their throughput capabilities. As a result, there has been a steady increase in the sales of batch cleaners versus other cleaning venues. There are several reasons why batch technology has caught up to other cleaning technology for high reliability devices. These reasons include cleanliness, dryness, statistical process control (SPC),
environmental footprint, and throughput.

Cleanliness
Since batch format defluxing systems do not rely on a fixed conveyor speed setting to determine the amount of wash, rinse, or dry an assembly requires, each process is independently controlled. For example, long washes may be combined with short dry times, allowing unique cleaning profiles to be developed for a particular batch of assemblies. Batch machines are also uniquely capable of providing real-time cleanliness testing. Because each process cycle is independent, the rinse water can be collected and subjected to ionic testing in real time. This analysis allows the machine to expand or contract the cycle time in order to meet the user’s cleanliness requirement. By knowing how clean the boards are at the end of the defluxing process, cleanliness testing becomes more predictable while producing
drastically lower failure rates.

Dryness
Drying is often the most overlooked segment of a defluxing process. Because the drying time is independently controlled, assemblies will only be subjected to the actual time required to eliminate all moisture under components and in between layers. Most batch format machines provide a rapid bake-out process, combining convection and radiant technology rather than a mechanical removal of moisture. This ensures that the specific drying temperature and time are achieved for thorough drying.

Statistical Process Control (SPC)
SPC is a required element of any high reliability assembly process. Common SPC mandates can be found in all quality standards such as ISO and TQM. Because each process element is independently controlled, each process step and result can be individually recorded for statistical analysis.

Environmental Footprint
Batch defluxing systems require about thirty gallons of water per hour, while inline processes may require as much as three hundred gallons of water per hour. With batch defluxing technology requiring only one tenth of the water and drain requirement of inline, as well as a fraction of the electrical current, it is logical that batch technology is less environmentally intrusive than most inline processes and has a smaller environmental footprint.

Throughput
The new high-yield batch technology preserves all of the advantages associated with batch processes while providing throughput rates equal to or better than an inline alternative. With a growing high reliability market, there is a higher demand for higher volume defluxing systems.

Increasing expectations of reliability and rising concerns over liability practically mandate the use of defluxing technology equipped with the highest degrees of process control. For more information related to this equipment, or to schedule a demonstration of the Trident series batch defluxer at the EMPF, contact Ken Friedman at 610.362.1200 ext. 279 or via email at kfriedman@aciusa.org.