IML problem 1

[sizzer33]

Hi all,

Just wondering if anyone can point me to the right direction in solving this IML issue.

Here are the info:-

- IML foil is PET 0.75mm
- Part to be IML is PC material.
- Mould temp during test, 45-55degC
- Part is a mobile phone front window. It is a rectangular part with only slight curve, transparent PC with IML foil to make a significant pattern and small opening for the front LCD. ITs very common on flip phones.

Problem:-
- Molded parts fail several test such as vibration abrasion test, temperature test, salt mist test.
- What happen is for example in salt mist test, the IML foil would peel off.
- Also, when the test fail, it would only occur randomly such as 2 or 3 fail parts out of 5.

Question:-
- does mould release agent affect IML foil adhesive properties. During mould test, we sprayed some mould release agent on cavity side during start of moulding.
- how bout the mould temperature affect on the IML foil adhesive properties?

Any advise is welcome. thanks

 

[patprimmer]

I think you answered your own question.

What is the function of mould release.

What is your problem.

Is there a great similarity between the two.

Have you draw polished the mould, especially the core so as to reduce the need for mould release.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules

 

[sizzer33]

Well in our plant, the tester do spray some mould release when they start the machine to avoid part from sticking. The part comes out ok after a few shots.

Just wondering if anyone had any problem with their IML foil when they spray mould release agent during moulding.

My problem is one the moulded parts are brought to testing, the IML foil will peel off the parts.

 

[trxt]

why dont you use pc films such as lexan? it is more durable and provides good adhesion with pc.

 

[patprimmer]

PC film is more durable than PET. That's news to me, especially if exposed to scratching, or many common chemicals or repeated flexing.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[trxt]

Answers: Mould release agent should not affect the adhesion. Film and molten resin type selection affect the adhesion.
Not mold temperature but resin temperature affect the adhesion.

If you are applying taber abrasion test. You must find more durable films.
If you are applying thermal shock and if it peels off after testing. you must select proper film which can be bonded with pc resin strongly. This choice mostly is the film that has been produced from the same type resin.

 

[patprimmer]

In my experience, mould release, especially Silicone types do reduce adhesion of everything to the surface of the material.

If they are incorporated into the compound they will migrate to the surface during moulding.

If they are sprayed onto the mould they will not effect the surface between the film and the resin IF thy can be excluded from that area. We see no evidence here to date to suggest that the interface has been successfully protected from MR spray

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[Pud]

Silicone release spray:

We mould parts that require printing or Chromium plating.

When we run these parts, Si spray is locked away and not used anywhere on site - it is very pervasive and contaminates processes tens of metres away (been there, done that, had the rejects to prove it!)

Cheers

Harry

http://www.tynevalleyplastics.co.uk

 

[sizzer33]

Cheers everyone!! It at least help us to determine which direction to go now. Thanks

 

[sizzer33]

One question to txrt.

Regarding the adhesive properties of foil and plastic part, doesn't the adhesion between these 2 properties created by an adhesion layer on the IML foil instead of the type of foil material?