this macbook air (model a1466) arrived on my desk with no backlight.  supposedly the unit was not exposed to any liquid.

they all say that…

the easier fix would be the backlight filter, and that tested as a fail, but when replaced it, we still did not have any light.  so… on to the next step which was to remove the board, flip it over and look closely at the backlight driver.

whoa nellie!  there’s a problem there and is sure does look like dried up liquid corrosion to me.

let’s put some heat to it and flip it over.  btw – the yellow tape you see has a very high heat resistance and we use it to shield other areas of the board to help protect nearby components.

sure ‘nuf – there’s some corrosion in that there backlight chip.  let’s get a different light and take another look.

btw – the size of this 25 pin chip is 2.5mm by 2.5mm.

let’s get a closer look at the pad area.

that’s a hot mess right there.  those 25 pins are not supposed to be touching each other, but the liquid created a bridge.  or i should say the contaminants in the liquid created a bridge between the contact points and blew the chip.

so i cleaned that area up, slapped a new on, and we can now see our screen!  yay!  problem fixed.