Heat-sensitive devices are prevalent in a wide variety of electronics products including image sensors, touch panels in Smartphones, PDAs, laptops, TVs and all types of LCD panels, among others.
Because of their low-temperature requirements, assembling such devices can be quite challenging. Unfortunately, some of today’s most commonly used adhesives cure at a relatively high temperature (100°C) and may experience warpage problems induced by mechanical stress, which can damage the heat-sensitive parts of the product.
Attempts to develop lower curing temperature materials have resulted in some workable, but less than optimal adhesives. One approach is a two-part epoxy system that cures at room temperature. But, the required mixing and extrusion process for these materials is messy, costly and entails manual labor, which is far less efficient than automatic nozzle dispersion methods. Plus, these two part materials have a fairly short work life: material must be used within two to three hours or its viscosity becomes too high.
But, global competition for manufacturers of these products that contain heat-sensitive devices is fierce and lowering manufacturing costs is a necessity for competitiveness. So, finding materials that can help reduce overall manufacturing costs while still providing a robust process is essential.
Addressing the demands of consumers and manufacturers, Henkel has developed an electrically conductive paste that can cure quickly at a relatively low temperature, which keeps the heat-sensitive parts safe from potential damage. The original version of the material – Hysol QMI516LCTM is a silver-filled, electrically conductive paste designed for applications that require low-temperature oven cure (65°C for 3 hours) or Skip-CureTM (30 seconds at 100°C). The material is hydrophobic and stable at high temperatures and produces void-free, strong bondlines with excellent adhesion to a wide range of surface finishes including solder resist and flexible tape. Packages or devices manufactured with this material also have high resistance to delamination and popcorning, even after multiple exposures to lead-free solder reflow temperatures. This Hysol® product can be used tomount temperature-sensitive parts such as CCD camera modules as well as for conductive die attach applications for various surfaces of PBGAs, Smartcards, CSPs and others where customers require a low temperature cure of a very fast conductive cure and JEDEC performance.
Of course, Henkel hasn’t stopped here. In keeping with our promise to continually innovate beyond current requirements, we have developed a next-generation technology that delivers improved performance. Building on the success of the older-generation material, Henkel scientists have formulated Hysol® QMI516IETM, which helps manufacturers realize an even lower curing temperature (60°C) for greater effectiveness.
Hysol QMI516IE can be cured for 60 seconds at 90°C, 5 minutes at 75°C or 60 minutes at 60°C, which offers electronics specialists incredible processing flexibility and application-specific customization. The material has shown good and stable electrical conductivity through the adhesive bond and the pot life is at least 8 hours – a more than 6 hour improvement on the two-part epoxy systems mentioned previously. This versatility also reduces cost and extends manufacturing options.
All of these advantages combine to provide manufacturers of heat-sensitive device containing products exactly what they need: a low temperature, fast curing electrically conductive adhesive for modern processes. The one-part, low temperature cure of Hysol QMI516IE also addresses the cost quandary by significantly reducing overall manufacturing costs without sacrificing robust processing of today’s higher functionality consumer products.
So, how low can we go? Who knows? This latest Henkel innovation is truly enabling and is only the beginning of our ongoing work for this class of materials. Future development will focus on extending the work life and improving cure times. Stay tuned!
For more information on Hysol QMI516IE or any of Henkel’s advanced electronics materials, call the company headquarters at 949-789-2500.