Management method of ultrasonic welding process for the housing

The housing of the AC/DC Power Adapters — Desktop & Wall-Mount is assembled using ultrasonic welding. This page introduces part of our thorough management methods for the ultrasonic welding process.

By reliably performing ultrasonic welding, it is possible to prevent accidents in advance where live parts become exposed from the enclosure.

1. Pre-production Preparation

The production engineering staff will install and adjust the horn of the ultrasonic welding equipment and set the welding conditions based on the instructions.
After adjustments, a dummy board is inserted into the enclosure and one welding operation is performed.
After welding, a drop test conforming to safety standards is conducted by a member of the IPQC (In Process Quality Control) department.
After the drop test, it is visually confirmed that the welded part of the enclosure is not cracked.
The enclosure is opened using a dedicated tool, and it is confirmed that 75% or more of the welded area is reliably fused.

Production begins after confirming the above.

2. After Production Starts

1. Production Line

A checkpoint is installed between the ultrasonic welding process and the next process to prevent skipping the welding step.
The operator of the ultrasonic welding process visually checks all the welded areas after welding.
In the subsequent automatic electrical characteristic inspection process, before connecting the enclosure to the inspection equipment, it is slammed onto the workbench to confirm that the welded part does not open on all units.

2. IPQC

Every two hours, a member of the IPQC team performs patrol sampling inspection as described below.

After adjustment, a dummy board is inserted into the enclosure and one welding operation is performed.
After welding, a drop test conforming to safety standards is conducted by a member of the IPQC team.
After the drop test, the enclosure is opened and it is confirmed that 75% or more of the welded area is reliably fused.

After confirming the above, if any abnormalities are found in items 2) or 3), all units will be subject to rework by tracing back to the last IPQC patrol inspection, according to our company's ISO abnormality handling regulations.

3. OQC (Outgoing Quality Control)

From the shipping lot, 5 units are sampled and the gap between the upper and lower enclosures at the welded part is checked with a thickness gauge to ensure it is within the standard range.

For USB-type products in the 5W class where the ultrasonic weld line is particularly short, the impact applied to the enclosure during a standard drop test may be small, and any latent defect in the ultrasonic welding may not surface. Therefore, to apply greater impact than a drop test, the IPQC staff will connect a cable with attached weight to the enclosure and, from a height specified by internal standards, allow it to free fall as a test similar to a steel ball drop, and confirm every two hours that there is no damage to the ultrasonic welded part.