Management of the ultrasonic welding process for housing

By performing ultrasonic welding meticulously, it is possible in advance to prevent accidents such as exposing live parts to the casing.

1. Preparation before starting production

According to production engineering standards, we set the attachment of ultrasonic welding horns and adjust the setting for ultrasonic welding conditions.
After completing the adjustment, we place the dummy board in the chassis and perform one welding.
After the welding, a person in charge in the in-process quality control (IPQC) division conducts a drop test conforming to safety standards.
After carrying out the drop test, we confirm that the ultrasonic weld of the housing is not broken by visual inspection.
Next, we open the enclosure with a special tool, check the ultrasonic weld surface, and confirm that 75% or more of the welded part is reliably fused.

2. After the start of production

2.1 Production line

During the ultrasonic welding process, in order to prevent skipping, a part is set up between the ultrasonic welding process and the next process.
After ultrasonic welding, the operator in the ultrasonic welding process visually checks all ultrasonic welds.
Before connecting the chassis to the inspection facility in the automatic process of inspection of the electrical characteristics of the next process, we confirm the total number so that the welded part does not open by hitting the housing against the workbench.

2.2 IPQC

Once every two hours, from the production line, IPQC personnel will carry out the following sampling inspection.

After completing the adjustment, the staff place the dummy board in the chassis and perform one welding.
After the welding, IPQC staff will perform a drop test conforming to safety standards.
After carrying out the drop test, the case is opened, the welded surface checked, and confirmed that 75% or more of the welded part is reliably fused.

If the above is confirmed and an abnormality is found in the steps 2 and 3 above, we follow the abnormality treatment regulation of our company’s ISO and go back to the IPQC patrol inspection point immediately before that and carry out a total rework.

2.3 OQC (Out-going Quality Control)

Five units are pulled out from the shipping lot and the clearance between the upper and lower casing of the ultrasonic weld is checked with a thickness gauge to confirm that it is within the range of the standard value.

In the case of a 5 W class ultrasonic welding wire having a particularly short USB type wire, , though in conformity with the safety standards. So, even if there is a potential defect in ultrasonic welding, it does not become apparent. Therefore, in order to increase the impact force applied to the enclosure more than the drop test, a test similar to the steel ball drop test is conducted by connecting weighted cables to the enclosure.The IPQC staff will confirm one unit every two hours to check that the ultrasonic weld is not damaged by letting the weight fall freely from the prescribed height.

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Since 1989, UNIFIVE has maintained the quality of their AC power adapters and switching power supplies through rigorous quality controls.