Liquid Optically Clear Adhesive (LOCA) is a glue (UV glue/UV adhesive)sealant used to increase the durability of LCD screens, touch screen panels, mobile phones, laptops, tablets, glass retarders and 3D TVs. In addition to prolonging the life of these devices, LOCA increases contrast by 400%, extends battery life by minimizing light loss from reflection and makes the display more resistant to moisture, heat, impact and extreme fluctuations in temperature.
Preparation and Items Needed
Anyone setting out to replace a broken cell phone screen, tablet screen or a similar surface should be using LOCA glue. The device must first be prepared by removing the cracked screen and cleaning the LDC screen beneath. The batteries should also be removed, as the heating process prescribed can easily damage them. Before beginning, assemble the following:
heating mechanism such as a heat gun, blow dryer, hot plate or LCD separator machine.
Goof Off or other adhesive remover
3mm capacity syringe
replacement glass cover specific to the individual device make and model
Heat the Device and Remove the Glass
The front face of the device must be heated to between 200 and 230 degrees Fahrenheit using whatever mechanism is available. This is done in order to melt the existing LOCA or similar bonding agent holding the glass in place. Use the infared thermometer to check the surface temperature before attempting to remove the glass. Too much heat will burn the LCD screen while too little heat will cause it to crack. The screen will need to be heated to within the recommended temperatures several times during the removal.
Begin at the top of the unit where the speaker is located by using the spudger to slowly separate the glass from the LCD screen. Work the spudger along the top edge to gain enough leverage to slip the putty knife in along the entire length of the top edge. Reheat the surface and begin very slowly and steadily prying the glass away with the putty knife. Once the glass is removed, use the Goof Off or a similar adhesive remover to clean the LCD screen. It is important to note that some devices may have "home" and "back" sensors attached to one end of the glass which must be removed by using a combination of heat, patience and an X-acto Knife or razor blade.
Apply the LOCA Glue to the LCD Screen
A syringe containing 2 & 1/4 milliliters of LOCA glue should have been prepared the previous day and left to sit upright overnight with 1/4 of a milliliter of air at the top of the chamber. This allows air bubbles to rise to the top of the solution, keeping them off of the LCD screen. Force the air from the syringe along with a drop or two of LOCA and wipe clean. There should be no air in the syringe whatsoever before applying to the LDC screen. Use the syringe application nozzle to apply the LOCA onto the exposed screen in a two-ended "Y" shape similar to this: >--<. the glue will settle into a shape similar to dog bone. place device beneath magnifying lamp using spudger or very small screwdriver remove air bubbles and bits of debris.>
Replace the Glass Cover
Affixing the replacement glass onto the screen requires a steady, patient hand. Begin at the speaker end of the device and very slowly lower the glass into place, using the spudger and fingers to keep the glass gradually descending at an angle. Once the glass makes contact with the LOCA, the glue will slowly begin to disperse across the entirety of the screen. Use finger pressure to work any air bubbles to the edge of the screen and eventually out from between the LCD surface and the new glass.
Cure the LOCA with UV Light
The chemical compounds (UV compound/UV glue/UV adhesive) in LOCA are activated to the curing stage by ultraviolet light. Place the device under a UV lamp or into direct sunlight for 15 to 30 seconds and remove. Any LOCA glue that has overflowed can be wiped up or carefully scraped off with a razor.
Every device and cell phone model is different, so it is important to check with the manufacturer before disassembling to determine what sensors one might encounter when performing the glass removal. Also, some devices may require delicate application of tiny pieces of two-sided tape to protect input ports and volume controls.