 Nadine Blaesing Dymax Corp. Market Segment Manager Visit Website |
Nadine Blaesing is the market segment manager, Europe, for Dymax. She has more than 12 years of experience selling adhesives and providing technical assistance to the medical device market. Although she began her career as an applications engineer in Europe, and later in the United States, Blaesing eventually transitioned into marketing while keeping her focus on the medical device industry. Dymax specializes in the manufacture of light-curable adhesives, cyanoacrylates, epoxies, light-emitting curing equipment, and dispensing systems.
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Adhesives and Epoxies Q&A
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We have an application in which we would like to cover the edge of a silicon die that has been tacked in place with epoxy cured to a Valox/PBT base with an uncured epoxy. Then we’d like to add additional epoxy to a second bond location that ultimately bonds the Valox base to a Valox cover with a slight press fit covering the silicon die. After the press fit assembly, we would like to light or UV cure through the cover plate, curing both applications—the bond line between the Valox cover plate and the Valox base as well as the bond between the edge coating around the periphery of the silicon die and the Valox base. Are there any polymers that can transmit UV or light sufficiently to allow these types of cures? Is there a special light source required? Can the polymer be anything other then clear? Lastly, is there a medical-grade polymer that can achieve this?Answered February 17th, 2010 by Expert:There are a couple of ways to handle this application. A number of polymers can be used for a cover plate that will let light through, whether UV or visible light. One way is to use a tinted plastic such as polycarbonate or acrylic. Tinting the plastic with a dark blue dye will create the illusion of opaqueness but will let the proper wavelengths through the plastic to allow it to cure.
Finding the right balance of dye is critical. One way to judge the impact of the dye in the plastic or the transmission through the plastic is to measure the intensity of light coming through the plastic from the light source. You can calculate a percentage loss of transmission through the plastic in both the UV and visible regions. Most adhesives want to see a minimum of 200 mW/cm2, and some of the light sources on the market emit light of 20,000 mW/cm2. Even if the plastic blocks off 90% of the UV light and 70% of the visible light, this might be enough to allow the adhesive to cure.
If the plastic compounder uses a pigment to augment the tint, make sure that the level of the pigment is low and that it contains a material such as titanium dioxide.
A good field test is to hold the plastic up to the light. If you can see a shadow as you wave your hand behind it, you might have enough light coming through to cure the adhesives. Stay away from yellow-orange-red colors. Whites, blues, and greens are better. A number of medical grade adhesives and various curing lamps can be used for this application. I might recommend contacting Dymax Application Engineering to arrange for some free samples and to discuss the Try/Rent lamp program.