Ultrasonic Welding Process and Management at Our Company

The AC-DC power adapter's casing must be securely fastened. Reliable ultrasonic welding can prevent accidents in which live electrical parts are exposed from the casing.

1:Preparation before starting production

1. According to production engineering standards, we set the attachment of ultrasonic welding horns and adjust the setting for ultrasonic welding conditions.
2. After the adjustment, we placed the dummy board in the chassis and performed one welding.
3. After the welding, a person in charge of the in-process quality control (IPQC) division conducts a drop test conforming to safety standards.
4. After carrying out the drop test, we confirmed that the housing's ultrasonic weld was not broken by visual inspection.
5. Next, we open the enclosure with a unique tool, check the ultrasonic weld surface, and confirm that 75% or more of the welded part is reliably fused.
6. After the start of production

2:Production line

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

2.2 IPQC

Every two hours, an IPQC (In-Process Quality Control) officer conducts the following random inspection of the production line.

1. After adjustments, a dummy board is placed into the casing, and one unit undergoes welding.
2. After welding, the IPQC officer conducts a drop test to ensure compliance with safety standards.
3. Following the drop test, the casing is opened to verify that over 75% of the welding surface has adequately fused.

Suppose any abnormalities are detected during steps 2) and 3) by our company's ISO anomaly handling procedures. In that case, we will trace back to the last IPQC inspection and carry out a complete rework on all affected units.

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 standard value range.

Moreover, 5W class ultrasonic welding wire has 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, 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.