A customer sent PCBAs with visible rosin flux residue for DEZ-C743 testing. See the results from batch washing, DI-water rinsing and hot-air drying.
DoorbeheerA customer sent assembled circuit boards to DEZ for a PCBA flux residue cleaning test. Visible rosin flux residue remained around components, solder joints and across the PCB surface after soldering.
The condition did not meet the end customer’s delivery requirements. The manufacturer therefore needed a controlled process that could remove the residue from the assembled boards without relying on manual wiping.
DEZ evaluated the customer’s actual PCBAs and completed the cleaning test using the DEZ-C743 offline batch cleaning process. Before-and-after microscope images showed a clear reduction in visible residue.
| Project Item | Details |
|---|---|
| Werkstuk | Assembled PCBAs |
| Board construction | SMT and through-hole components |
| Verontreiniging | Visible rosin flux residue |
| Customer problem | PCBAs did not meet the end customer’s delivery requirements |
| Cleaning equipment | DEZ-C743 |
| Reinigingsmethode | Offline batch sproeireiniging |
| Volledig proces | Chemische was, DI-water spoelen en hete-lucht drogen |
| Evaluation method | Visual inspection and microscope comparison |
| Resultaat | Visible residue was significantly reduced |
The submitted PCBAs contained visible residue around component leads, solder joints and densely populated areas.
Microscope inspection revealed glossy deposits across an integrated-circuit package and the surrounding solder-mask surface. Additional residue could be seen between nearby components and around soldered areas.
Although the PCBAs had completed assembly, their surface condition did not meet the end customer’s acceptance requirements. Manual wiping was not an appropriate production solution because it could not consistently reach around component leads or remove contamination from complex areas.
The manufacturer needed a repeatable cleaning process that included washing, rinsing and drying.
Flux removes surface oxides and supports solder wetting during reflow, wave, selective or manual soldering. The residue remaining after soldering must be evaluated according to the flux chemistry, assembly design and product requirements.
Visible residue can affect:
Not all flux residue produces the same risk. However, depending on its chemical composition, moisture exposure and electrical conditions, soluble contamination may contribute to electrical leakage, corrosion or electrochemical migration.
For assemblies operating in humid, high-voltage or long-service-life environments, uncontrolled contamination may increase the possibility of insulation degradation or electrical shorts.
This is particularly relevant to automotive electronics, aerospace and defence equipment, new-energy systems, medical electronics and industrial controls. These products often require defined cleanliness and process validation before delivery or final assembly.
The customer supplied actual production PCBAs for testing. This allowed DEZ to evaluate the contamination and board construction before establishing the cleaning process.
The evaluation considered:
Testing the actual assembly is important because cleaning performance depends on more than the machine model. Flux chemistry, component layout, surface condition and liquid access all affect the final result.
The customer required complete cleaning of assembled boards rather than brushing one accessible solder-side surface.
De DEZ-C743 offline PCBA batchreiniger processes multiple assemblies in a two-level basket. Chemical spray washing, DI-water rinsing and hot-air drying are completed inside the same enclosed chamber.
This process was suitable for the customer’s samples because:
Load PCBAs → Chemical Spray Wash → DI-Water Rinse → Hot-Air Dry
The customer’s PCBAs were arranged in the two-level basket. Spray positions above, between and below the loading levels directed heated cleaning liquid towards the assemblies.
The cleaning chemistry dissolved and separated compatible rosin flux residue from component surfaces, solder joints and the PCB solder mask.
After washing, DI water rinsed away dissolved contamination and remaining cleaning-agent residue.
The rinse stage is necessary because washing alone can leave dissolved flux or cleaning chemistry on the assembly. DI water is used for rinsing; it does not replace the main cleaning chemistry when the flux is not water-soluble.
The cleaned PCBAs remained inside the chamber for hot-air drying. There was no need to transfer wet boards between separate washing, rinsing and drying stations.
The customer sample test achieved the main visual objective:
The test results apply to the submitted PCBAs, contamination, cleaning chemistry and process settings. A different flux formulation or assembly construction may require different cleaning parameters.
Controlled PCBA cleaning is not only a cosmetic process. When cleaning is required by the product specification, it helps prepare the assembly for inspection, electrical testing, conformal coating or final delivery.
For automotive electronics, aerospace and defence equipment, new-energy systems and other reliability-focused products, the cleaning requirement should be defined before mass production. Representative sample testing helps confirm whether the proposed process can reach the contamination and achieve the required result.
The DEZ-C743 provides an offline solution for manufacturers that need batch washing, DI-water rinsing and drying without installing a continuous inline cleaning system.
Send DEZ representative PCBAs with the actual post-solder residue. Please include:
DEZ will evaluate the contamination, cleaning process, basket loading method and suitable equipment configuration.
