First, you have to understand that OCA is a special glue, it is softer than solid but harder than liquid LOCA glue, we never got bubbles when use LOCA glue to refurbish LCD, that's because of bubbles can be removed easily from the liquid, but air can't pass through colloid easily.
Why does bubbles reappear?
Do you think you really removed all the bubbles after you put them in the autoclave like 5 minutes? the answer is "NO", the real process of bubbles removing is to squeezing the air out of the OCA after lamination, maybe you did not see any bubbles after bubble removing, but the truth is that the air bubbles has been separated to many many tiny bubbles that you can't see it by eyes, but once those tiny bubbles join together after few minutes or few hours, they will become like a tiny bubble you can see.
How to avoid this?
1, Choose a good quality glue, Mitsubishi is the most popular glue in the market now, it is very soft with good viscidity, there has 3 types of thickness in the market, 175um, 200um, 250um, honestly speaking, 250um is the best one for lamination and bubble removing since it has more space between glass and LCD to squeezing the air, but the cost of 250um is higher than 175um and 200um, so you can find most of the OCA glue in the market with marked thickness 250um is only 200um, some even only 175um. So, make sure you got the real 250um OCA, the only disadvantage of 250um glue is the LCD will be a little bit thicker than the original LCD after refurbishing, but most of the customers they don't care that.
2, Keep your OCA in a good condition such as 20C degrees, no sunshine, about 30% to 70% humidity.
3, Temperature, before laminating the glass on the LCD, i would like to preheat the OCA glue about 2 minutes with temperature 50C degrees, for iphone, i use cold press framed glass, so i laminate OCA on the LCD so i preheat the LCD, for samsung, after i put OCA on the glass then i will preheat the glued glass.
4, Thickness of the paint. All the glass has paint (such as black/white/blue/gray), and those paint minimum are 3 layers, a good quality white glass's paint should less than 35um,a good quality black glass's paint thickness should less than 15um, so if you bought the fake quality glass with more thicker paint, then it will be more risky to have bubbles problem. most of the tiny bubbles if reappear near the frame or bottom & top edge of your LCD, that's probally the paint problem.
5. Laminator's problem, the most important condition for laminator is vacuum, a pure vacuum can make the lamination be perfect and easy bubble removing, all the laminator from OCAmaster has been tested the vacuum over 200 hours before shipping.
If you fully understood what i said above, you will resolve the bubble issue easily.
-----by Alex
