Haze and lack of clarity are considered among the most vexing and stubborn of defects in the assembly of LCD screens and surfaces. Significant advances have been made in the optical quality and capability of liquid crystals and LEDs; however, these advances can be stunted by choices made further along in the assembly process. Specifically, liquid optically clear adhesives (LOCAs) used in the bonding of assembly layers can cause haze and light refraction either immediately or under certain aging conditions. The proper design of LOCA materials must take this risk of haze development into consideration. There are a number of effective approaches to minimizing or eliminating haze.
You have a lot of options regarding the packaging of your adhesives and coatings. In this blog installment, we will discuss characteristics, advantages, and concerns regarding one of the more unique alternatives: Bladder Bags
UV20GEL is a recent innovation from the polymer scientists at HumiSeal.
It provides additional durability and ruggedization for printed circuit boards in demanding applications including automotive, aerospace, and appliances among others. This flexible, high adhesion gel is used for staking taller or sensitive components to provide resistance to vibration and mechanical shock conditions.
Conformal coatings rose to prominence in protection of printed circuit boards (PCBs) about five decades ago. Through their use, early PCB failures due to dust and dirt, liquids, and humidity contamination were greatly reduced or eliminated. This in turn allowed for the longer warranties and improved reliability we see today. Early conformal coatings, many of which are still in use today, were comprised of polymers dissolved in various solvents such as MEK, toluene, or xylene.
An approximate evolution of conformal coating chemistries could be viewed as
- solvent-borne acrylics and polyurethanes
- waterborne acrylics
- synthetic rubber coatings
- UV-curable acrylated urethanes
- LED UV-curable acrylated urethanes
March 4th of 2020 represented a potentially seminal date for both suppliers and manufacturers within the printed circuit board industry. This was the date of release of four updated Guobiao or “GB” standards related to the VOC content and other harmful substances allowable within supplied inks, adhesives, and protective coatings in China. This change in regulations is the result of China’s three-year action plan begun in 2018. The plan is intended to improve air quality through reduction of VOC emissions by at least 10% as compared to 2015 levels.
The new standards are straightforward but can become difficult to understand as they are often implemented by city and by region.
Liquid optically clear adhesives (LOCA) provide superior optical enhancement and anti-glare properties in the manufacture of liquid crystal displays. Light, temperature and moisture can significantly affect the physical and optical properties of these adhesives, promoting yellowing or discoloration, delamination, and loss of adhesion. In this discussion, we will explain the use of “accelerated weathering exposure” in the design of LOCA and its advantages over more traditional individual factor analysis.
Packaging. Not the most complex subject when choosing a conformal coating, but treat the decision too lightly at your peril. There are a surprising number of options available, each suitable to very specific needs and conditions. In this brief presentation we will discuss, from smallest to largest, the various packaging choices available to you, along with the advantages and disadvantages of each.
Take a quick look at the photograph on your right. If you are in the business of PCB manufacturing with conformal coatings, does it frighten or concern you at all? Does the magnified coating appear to truly “conform” to the surfaces evenly? And if not, what effect, if any, might this have on the protection of your PCBs?
First of all, don’t panic. What you see in the photograph is not unusual and is not necessarily a problem. It is important, however, that if you are in the business of applying conformal coatings, you should have a clear understanding of some of the unique challenges they present.
UV curable conformal coatings have attained widespread use in applications requiring fast through-put times, such as automotive, white goods, and industrial control manufacturing. In addition to speed of cure, UV curable conformal coatings provide the advantage of high physical protection and chemical resistance for electronic systems. Traditionally the UV curing of coatings is an energy intensive process. One that uses high-power mercury discharge lamps, which as a result of use produce considerable amounts of heat and ozone. The recent introduction of new, high-output LED UVA light units allows for the successful cure of conformal coatings by using between 365nm and 395nm wavelength of UVA light, effectively curing with minimal heat and no ozone generation.
Adoption of plug in -electric vehicles (EVs) has been slower than many expected, but there is little question the next few years will see adoption accelerate. Your hypersensitive dog will have to find new visitors to harass when your delivery drivers arrive without notice, driving to your door silently in all-electric commercial vans. Many of your favorite suppliers and stores have already ordered these vehicles. Game-changing battery and charging developments are eliminating range anxiety, and autonomous driving controls and safety innovations are in the final stages of building our trust.