Visit：2777   Date：2023-11-13

The LED bead copper wire process has been researched and developed by LED lamp manufacturers due to its cost reduction, and has been applied by many manufacturers. However, according to feedback from customers on the actual application of copper wire welding, there are many problems with the copper wire process. Below, we have summarized these common problems, hoping to be helpful to everyone.

1. The aluminum layer at the first welding point is damaged, especially severe for aluminum layer thickness<1um;

2. The second solder joint defect is mainly due to the difficulty of copper wire bonding with the bracket, causing the crescent to crack or damage, resulting in poor welding of the second solder joint and posing a reliability risk during customer use;

3. For many brackets, the power, USG (ultrasonic) friction, and pressure parameters of the second welding point need to be optimized, and the excellent rate is not easy to increase;

4. Copper wire oxidation causes deformation of the gold ball, which affects the product qualification rate. It is difficult to unpack during failure analysis;

5. The training cycle for operators and technicians is relatively long, and the skill requirements for employees are relatively high compared to those for wire welding. At the beginning, it will definitely have an impact on production capacity;

6. The MTBA (hourly output rate) of the equipment will decrease compared to the gold wire process, affecting production capacity;

7. The cost of consumables increases, and the lifespan of copper wire cleavers is usually reduced by half or even more compared to gold wire. Simultaneously increasing the complexity of production control and the cost of ceramic nozzle consumption;

8. Material confusion is prone to occur. If both gold and copper wire processes are involved in production, production control must pay attention to storage life and distinguish material lists. If the wrong or oxidized wire is used, it can only be scrapped. Misoperation warnings often appear, increasing the risk of defects;

Compared to gold wire welding, in addition to the ignition rod (EFO), there is an additional forming gas (synthetic gas) protective gas delivery pipe, and the positions of the two must be aligned. This directly affects the yield. Accurate control of protective gas flow, increased cost with more use, and high defect rate with less use;

10. Aluminum Splash It is usually easy to appear in wafers with thick aluminum layers. It is not easy to identify the impact, but be careful not to cause a short circuit in the circuit Easy to crush PAD or solder ball. Causing low test quality or customer complaints;

11. Oxidation occurs after threading, without standard judgment risk, which can easily cause poor contact and increase the defect rate;

12. It is necessary to re optimize the standards for wire pull, ball shear testing, and SPC control wires. The current standards for using gold wires may not be fully applicable to copper wire processes;

13. There may be some limitations to the bottom structure of the first solder pad, such as Low K die electric, those with through layer holes, and those with circuits at the bottom, which require careful evaluation of risks. The existing wafer bonding pad design rule requires in-depth optimization of the copper wire process. But nowadays, packaging factories that use copper wires seem to be insufficient to affect chip development;

14. The copper wire process may have reliability issues when using non green plastic sealing adhesive (containing halogen elements). The presence of fluorine or other impurities on the pad can also reduce the reliability of the copper wire.

The evaluation of things like Die to Die bonding and Reverse bonding is not yet complete.

16. Due to customer resistance, the copper wire process is still difficult for some customers with high reliability requirements to accept, and even more so, it loses customer trust.