“Will exposing areas of a PCB board that are not covered by an adhesive or conformal coating to UV curing energy damage the board in anyway?”

Any frequency of energy that gets impinged onto a substrate has two options: it can get reflected, in which case it is harmless, or it can get absorbed, in which case it will turn into heat. Some light-curing equipment, like the Dymax BlueWave^® spot lamps, have an intensity adjustment feature which allows for the ability to reduce unneeded energy. Adjusting the intensity reduces any excess energy that may turn into heat and damage temperature-sensitive substrates.

Adhesives, Curing Equipment, Electronic electronics assembly, Light Curable Adhesive, Light Curing Process, light-curable adhesives, PCB coating, uv curing, uv curing lamps, UV/Visible Light Curing Adhesive

“Is there a UV-curable, medical-grade (safe to use in the body) biodegradable adhesive of any kind on the market right now? If not, would it be possible to formulate the adhesive?”

Dymax does not presently pursue implantable applications for our adhesives, and we are unaware of any adhesive on the market that would be biodegradable. Consequently, we cannot comment on the feasibility of such a product.

Adhesives, Medical biodegradable adhesives, Light Curable Adhesive, light-curable adhesives, Medical-Grade, Medical-Grade Adhesive, UV Light Curing Adhesive, UV/Visible Light Curing Adhesive

“Guidelines for Protecting Light-Sensitive Adhesives from Curing in Dispensing Equipment in Manufacturing Environments”

Unfortunately, manufacturing facilities that use standard fluorescent lighting sometimes have a problem with the polymerization of UV/Visible light-curable adhesives in dispenser tips and lines. The chemistry of these products make them extra sensitive to light, so extra measures must be taken to insure that unwanted polymerization does not occur.

To prevent this problem, manufacturers should shield needle tips and lines from light exposure. Incorporating lines that are black, opaque, polyethylene plastic will completely block light from the adhesive and eliminate the chances of unwanted polymerization. Dymax provides light-blocking materials for syringe needle tips. If these measures are insufficient and a process can’t be shielded through use of light-blocking materials, the fluorescent lamps in the facility could be retrofitted for existing incandescent and fluorescent fixtures.

Adhesives, Coatings, Dispensing Equipment Dispensing Equipment, light-curable adhesives, UV Light Curing Adhesive, UV/Visible Light Curing Adhesive

“We are observing a cracking problem in the bonding of a PVC tube and component of PC-144R with a 50% Cyclohexanone + 50% Tetrahydrofuran solvent mixture. Please suggest an alternative solvent for bonding the above component. Also describe why the polycarbonate is showing cracks when used with aforementioned solvents.”

There are cases where the PC tends to crack upon contact to attacking chemicals like ketones (Cyclohexanone, MEK) , ethers, and esters (Tetrahydrofuran):

1. Applied stress due to joint design: when both parts are pushed into each other putting them into tension. To resolve, we recommend changing the design.
2. Residual stress due to the molding process: when the molded PC does not cool down consistently. An annealing step (time and temperature to be determined) will relieve residual stress.

I would recommend looking at the possibility of stress within the Polycarbonate and make changes to design and/or process accordingly.

You can also look into switching to a light-curable adhesive, which is typically less harsh to Polycarbonate. For bonding PVC to PC, Dymax has a variety of products if you are interested exploring this path further.

Adhesives bond PC, bond PVC, PC cracking, Plastic Bonding, Plastics, Polycarbonate, UV/Visible Light Curing Adhesive

“One of the materials I’m using has exhibited syneresis. What is the best way to reverse the syneresis?”

A few thickened adhesives (VT and GEL grades) occasionally exhibit syneresis. Syneresis appears as a thin film or puddles of low-viscosity adhesive on top of the thicker adhesive. Sour cream and yogurt are familiar products that also exhibit syneresis. The composition of the low-viscosity syneresis liquid is chemically identical to the thickened material. It has the same chemical and bonding properties but the viscosity is much lower.

Time and colder temperatures can promote syneresis. We would recommend using a First In, First Out (FIFO) inventory control. FIFO inventory control can help control the amount of time a product is stored before use. We would also suggest that syneresis-prone materials are not refrigerated. In fact, mild heating can reverse the syneresis in some products.

Once syneresis has occurred, mixing is the most common method of returning the mixture to a homogeneous state. Mixing can be accomplished with a traditional paddle or spatula (being careful to minimize air entrapment) or mixing can be accomplished through the use of a static mixer.

Adhesives gel adhesives, light-curable adhesives, syneresis, syneresis in adhesives, UV Light Curing Adhesive, UV/Visible Light Curing Adhesive

“What wavelengths are typically associated with depth of cure vs surface cure?”

Depth of cure is typically accomplished using long wave, UVA light (320-390 nm). Surface cure is typically done using short wave, UVB light (280-315 nm). For more information on curing with light, see DYMAX’s Comprehensive Guide to Light-Curing Technology.

Uncategorized curing with light, depth of cure, Light Curing Process, light wavelengths, light-curing adhesives, light-curing technology, surface cure, UV/Visible Light Curing Adhesive

“We use 1184-M-T, 1184-M-B, and 1184-M-VT epoxies for various uses. What is a good solvent that can take apart lenses glued together using 1184-M-T adhesive?”

If your lenses are made of glass you have several options, as glass is resistant to the solvent removal methods suggested below:

There are a few chemicals that will dissolve or swell 1184-M-T or any other light-curable acrylate, such as Dichloromethane, MEK, or Acetone. It may take some time for the solvent to migrate all the way in between the laminate, so the time depends on the size of your parts. A more gentile method is to soak the lenses in isopropyl alcohol (IPA) or even use warm IPA with the help of an ultra-sonic cleaner. I would also suggest this method if your lenses are made of plastic since the solvents mentioned first will also damage it.

Adhesives 1184-M Series, 1184-M-T, adhesive removal, bonding lenses, Light Curable Adhesive, light-curable adhesives, UV/Visible Light Curing Adhesive

“I would like to attach 72D Pebax extruded tubing into the ID of a Polycarbonate tube. What is the appropriate gap-per-side if I want to use DYMAX 204-CTH UV- curable adhesive?”

The optimum gap size for UV bonding applications (in general) is 0.002-0.006 inches, or 0.05-0.15 mm. In catheter bonding applications, where a Pebax tube is being bonded into a Polycarbonate Y-connector, we often see bond gaps around 0.1 mm per side. The DYMAX 204-CTH-F family is a very good choice of products to use for this type of application and substrate combination. Another product to consider is 208-CTH-F.

Adhesives, Catheter Bonding, Medical 204-CTH-F, 208-CTH-F, bonding Pebex tubing, Catheter-Bonding, Medical-Grade Adhesive, Pebax, UV Light Curing Adhesive, UV/Visible Light Curing Adhesive

“Can you recommend the most appropriate UV-curable adhesive to bond ABS connectors to polyurethane tubing in a medical device application? It is a polyether aromatic polyurethane tube to a transparent ABS connector.”

For this type of application I suggest trying DYMAX 1161-M. This adhesive cures with UV and visible light and exhibits good adhesion to ABS and PUR. It also fluoresces blue for quality purposes. If you are interested in See-Cure patented color-change technology, I would recommend DYMAX See-Cure 1201-M-SC. This product is blue and helps verify that enough adhesive has been dispensed. Upon exposure to UV/visible light, the adhesive turns clear to confirm complete cure.

Adhesives, Medical 1161-M, 1201-M-SC, Light Curable Adhesive, light-curable adhesives, Medical-Grade Adhesive, See-Cure, UV Light Curing Adhesive, UV/Visible Light Curing Adhesive

“We need to glue an epoxy-coated magnet to a copper-clad FR4 PC board. The UV-cure glue needs to resist mechanical shock without cracking. Any Ideas?”

DYMAX offers 6-625-SV01-Rev-A, a flexible light-curable adhesive with secondary heat cure and activator cure capabilities for shadowed areas. Its high viscosity of 10,000 cps also enables it to be dispensed from the outside and act as an edge-bonding material.

Adhesives 6-625-SV01-RevA, Bonding FR4 PC Board, Light Curable Adhesive, Light Curing Adhesive, light-curable adhesives, UV Light Curing Adhesive, UV/Visible Light Curing Adhesive