How to prevent backside mold chipping on bga substrate?

Guest

Hi,
Nice day!
I like to know what are the root cause that cause backside chipping on substrate after sawing? It often happen on the last cutting saw line.
Is it due to blade sawing during sawing process or during molding process due to mold void?
Cheers
ProcessEngrGal

Posted: Tue May 17, 2026 10:54 pm Post subject:

Hi, can you describe your problem more? Are you concerned with die backside chipping? Is sawing here the 'wafer saw'? Is your die 'face-down' on the substrate and its backside covered by plastic mold? Pls add more info because there are many kinds of problems using the same terms.

Posted: Wed May 18, 2026 12:08 pm Post subject:

Hi Guest,
My problem here is concern on bga substrate mold chipping, and not wafer chip. Mine is the back end process and not the front process... is when package doing singulation for package. It often have chipping on the compound side o f the substrate, and it happens at the last cutting line.

Guest

Is the chipping exposing an internal feature or not? If yes, then delam might also be an issue. You need to do CSAM on a few samples. If not, you need to analyze the fracture surface and microcracks around it, so you can pinpoint the direction of the stress causing the issue. Look for signs of voids in the fracture surface too. Once you know the direction of the stress, hypothesize what's causing the problem. Then simulate all your hypotheses. By the way, are you seeing voids in your good samples? If you have a microfocus xray machine you can check for voids in a set of samples so you'll know if you really have a voiding problem. Otherwise I think this is just a mechanical stress problem.

Jimmy Boy

Guest

Below are my suggestions that potentially will cause the backside chipping as you mentioned:

1. Vacuum table planarity
2. Saw parameters
3. Saw sequence
4. Frame tape stretch
5. Bubbles on adhesion tape
6. Molding integrity

Wink

AE engr