There’s a classic lesson here…iPads can be really frustrating to work on and the iFixit guides, while great for disassembly, really don’t cover all the intricacies of re-assembly. Getting everything just right is not at all obvious to someone who has never worked on iPads before.
Here are some guidelines:
- The stock adhesives on most iPad digitizers is not very good. A few vendors are starting to supply digitizers with Tesa 61395 or 3M 300LSE adhesive but what you will generally find is some stock “black” tape that has poor adhesion and is a little too thin. The trick is to remove the stock tape and apply a quality adhesive in it’s place. BowlerTech Adhesive has some nice pre-cut 3M tape that you apply to the housing or you can get rolls of Tesa Tape here on iFixit.
- Removing the previous adhesive from the housing insures that your digitizer will adhere properly. Using acetone works well but be careful not to get it on the plastic elements or cameras. IPA is a little less effective but doesn’t damage plastic and it still works.
- If your iPad has dented corners, you really should try to shape them out otherwise it may impede the glass from fitting properly or it will apply a stress point that will cause the glass to crack next time it is dropped. There are expensive tools to do this but a simple metal spudger works well. Use the rounded end for corners and the flat end for sidewalls. I use a jewellers hammer for a light touch as the aluminum sidewall can be easily damaged.
- Cleanliness - There are three optical surfaces that you have to insure are clean. The LCD face, the Digitizer inside glass surface and the Digitizer outside glass surface. The replacement digitizer should have a plastic protector over it but they sometimes still have smudges or fingerprints depending on the quality level of the supplier. The LCD may have some scratches due to the cracked screen leaving glass dust behind. The LCD surface is very delicate and the less you interact with it the better. I use compressed air to remove as much of the dust as possible, then a LensPen brush to gently remove what’s left and the LensPen cleaning side to remove smudges or fingerprints. As with testing, you want to insure the surfaces are clean prior to sealing the device otherwise you will see that smudge every time you use the iPad and it will drive you insane :>).
- Flexes - Each iPad has the Digitizer flex folding in a different pattern. You have to insure the flex is folded and inserted within the housing in the right way otherwise it will either apply upward pressure on the digitizer, which will make it lift over time, or it will kink and lead to Touch or Home Button issues.
- Testing - always re-assemble (without sealing) and do a full test on the device. Check the Touch across the digitizer, the cameras, sensors, buttons etc. You don’t want to find out that the camera is blurry because it has glue residue on it after you’ve sealed the device ;>). Personally I do a full test with the adhesive already in place so that I can see how everything fits together.
- Only when everything works and is clean do you want to seal the device. Remove the adhesive covering without smudging the surfaces, insure the flexes are in proper position and lay the digitizer in position. A quick blast of compressed air will remove any dust particles that migrated in between the digitizer and LCD. I do a last quick check to see if the Touch Screen works and then apply pressure all around the housing to set the adhesive. You can stack some large books over the iPad for a few hours to apply a consistent pressure and insure the adhesive sets properly.
Every tech develops their own methods and there is no “one right way” to do this. But the simple advice above will allow you to get good to great results.