In the wearables market, the goal of joining parts together is not necessarily to be seamless. For these devices, the major manufacturing question is how to integrate high technology – with its metalized circuitry – into items that flex with the patient’s form. Manufacturers must incorporate the right welding or bonding technology to enable such flexibility while connecting electrical components.
Here, hot bar bonding, which uses a thermode (or hot bar) to create an electrical interconnection between materials under a controlled pressure, is often used. The small, flexible characteristics patients expect from wearables can be achieved by forcing layers of material together in this way.
Anisotropic conductive film, or ACF, is a laminating or pre-bonding layer used when a fine-pitch is required and where selective reflow soldering cannot be applied. This facilitates, for example, interconnection between flexible circuit boards and displays. The ACF material consists of adhesive filled with conductive particles and a protective layer. Once ACF laminating is completed and the flex has been aligned to match the traces on the substrate, the thermode (hot bar) is again actuated to heat the parts to final bonding temperature under controlled pressure for the final bonding step. With newhorizon Hot Bar Desktop Series systems, the small, flexible characteristics patients expect from wearables can be achieved. These systems bond layers of material, for example, the gold used to monitor heartrate from contact with the skin, or flexible batteries to power whatever function a device performs.
ACF bonding is one of several hot bar techniques, including hot bar reflow soldering, in which two parts are coated with solder before the solder is melted to connect the parts. Another technique is heat staking, a pulsed heat process for joining a plastic part with another part made of plastic or another material to form a riveted type of joint.
Of course, every application of these technologies requires careful engineering. It is best to confer with experts when developing product manufacturing programs that integrate advanced welding or bonding. For this reason, it is paramount that manufacturers consult welding or bonding expertise and undertake a diligent design process. Amada Miyachi Europe facilitates both of these goals.
Device manufacturers have many welding and bonding technologies to choose from when engineering their manufacturing processes. Some technologies are best applied to Class III devices, and others offer more to wearables and other non-invasive technology. In every case, it is beneficial to understand the benefits and drawbacks of technologies that perform similar functions when making a decision. For any manufacturer, it is always wise to ensure that the equipment you purchase utilizes the appropriate technology for your task, and not just the technology a supplier may have to offer from a limited product portfolio.