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Cover tape tearing

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#38473

Cover tape tearing | 14 December, 2005

Im from a semiconductor manufacturing company and we received feedback from customers about cover tape tearing on 16mm heat activated cover tapes...the manifestation of the tear is that it starts from both sides of the seal and continues towards the middle to form a letter "V" or a "U". There is an evident struggle on the tape because the tear appeared rugged. There is limited technical papers on this and I would like to understand if this phenomenon is normal at the SMD process and if there were, what have been done...take note that the cover tape material we are using is an improved one already.

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Rob

#38478

Cover tape tearing | 15 December, 2005

Hi Liza,

We tend to see it on the larger plastic tape sizes & lower volume parts - such as smd connectors, fine pitch reeled IC's, BGA's etc. We don't tend to get it on high vol parts such as logic, 8 & 16bit micros, v-regs etc.

Could this be due to the volume manufacturers either using better equipment, or the heat sealing machinery prefering longer runs?

We have also noticed this to be more prevailent on certain types of surface mount machines & feeders.

This can also be a problem on glued tape.

Cheers,

Rob.

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00629

#38479

Cover tape tearing | 15 December, 2005

Hi Rob,

We encountered it on a 6x6mm device, hence, we could consider it as fine pitch. I suppose that it may also have something to do with improvements in the speed of the feeders. Honestly, we don't have that visibility bec our customers do not usually provide that information. But that info would be useful in verifying different scenarios at our end that could result to cover tape tearing.

If you don't mind, on what sm machines & feeders is it more prevalent?

Yes, it could still be tape related or sealing process related and we're doing experiments currently. My problem is I don't have visibility on the customer's end so we are at a loss on how to make our packaging robust no matter what the conditions are at the customer.

Thanks a lot.

best regards, Liza

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Rob

#38480

Cover tape tearing | 15 December, 2005

Hi Liza,

We've seen it occaisionally in house on Universal GSM 8,12,16mm but not on Fuji (except when a feeder's not used for a while). Also on 44, 56 & 72mm (the smaller vol parts I mentioned earlier. It tends not to affect the Hoover Davis Feeders so much. Some of it may also be down to feeder age. Also we put all of the awkward, large & low vol parts down with the GSM - so that's where problems would occur.

At customer's sites I've seen it mainly on small machines such as Quadras, Versatronics, the occasional Quad, and also on some Mydata, Europlacer & Philips machines - however there are a disproportionate amount of these in the market so you would expect to see this anyway.

We have in the past conducted pull tests on cover tape & subsequently rejected product (where it hasn't caused us major problems to do this).

What machines are the customers using & what are their feeder maintenance programs like?

Hope this helps,

Rob.

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#38482

Cover tape tearing | 15 December, 2005

After re-reading your posting, Liza, I�m doing yet another correction to my reply. Are you using the same taping machine for all your components or could you narrow it down to one taping machine? Is it a fully automated taping process or more likely a semi or manual taping process? Did you check the temperature setting on the heat sealer and measure the temperature with a probe? Are there settings to be changed on the pressure of the heat sealer head? Is the carrier tape surface soft and glossy or dull? You could also check, if the tape pockets are too shallow for this particular component and the components poke through the cover tape?

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GS

#38485

Cover tape tearing | 15 December, 2005

Hi Liza, several years ago we had problem like that only with Carrier Tape made by Ploycarbonate material and by using High Speed pick & place. Very few pbms met by using low speed P&P machine.

Problems have been solved by using Polystirene Carrier Tape (Conductive)and by requiring our component suppliers to use such kind of Carrier Tape.

To seal Cover Tape (ie AA...) against Polystirene Carrier Tape it requires less temperature and pressure as well then sealing on Polycarbonate CT, it means not overstress/overheat the cover tape sealed area, avoiding so to begin Cover Tape tearing effect when submitted to pull and feeding mechanical forces (like Tape Feeder when running at High Speed)

Regards...........GS

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#38500

Cover tape tearing | 15 December, 2005

Liza

Could increases in adhesion due to exposure to high temperature and humidity in storage environments be an explantion to this cover tape excessive bonding issue?

We agree with GS that heat bonding is so 1970s. Most heat bonders can fairly easily be retrofit to pressure.

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GS

#38503

Cover tape tearing | 15 December, 2005

Yes Davef, storage condition and long time remaining on shelf could effect pealing strength, but we experimented that by using Polystirene Carrier Tape also this problem was reduced almost to zero.

Df, If I am not wrong when you talk about pressure sealing, you are referring to PSA ?(pressure sensitive attivated) Cover Tape sealing with no more heating but only by pressure. PSA sealing is a technique that has some positive points but not so good enough to be compared to Polistyrene Carrier Tape and Cover Tape sealed by Thermal and Pressure (low)method.

I would not suggest to use PSA cover tape.

The only negative point for Polystirene material is that is less conductive then Polycarbonate material, but any way is enough to protect for long time the components from ESD as for supllier specifications.

Regards.......GS

PS: Liza, you could find some good info about tape and reel specification for SMDs on Standard EIA-481 (1-2-3) and recent EIA-200 (? not sure)

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Liza

#38506

Cover tape tearing | 15 December, 2005

Stefan - We are using an automatic sealing equipment and have several controls also. The particular machines used for processing these products could be narrowed down to 5 machines at most. The sealing temp, pressure and dwell time are checked on a regular basis. Because the product affected is a volume runner, we don't change the settings often. The seal heads (that has a direct contact to the cover tape) are cleaned after a defined no. of touchdowns. We are also monitoring PBFT every 8 hours and during set-ups using a tightened controls of 20-80 gms from 10-130 gms reqt based on an initial analysis that the higher the PBFT, the higher the chances of tearing. This control should also compensate for whatever aging and environmental conditions the products may be subjected to when they exit the plant. Our cover is AA and our carrier tape is a monolayer polystyrene dull finish with a thickness of 0.3 mm. Does the finish contribute to this problem?

Thanks.

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Liza

#38507

Cover tape tearing | 15 December, 2005

Hi Rob,

I would be asking the customers about that. I've read somewhere that teflon is used on feeders, is this a standard and does the absence or presence of this contribute to tape tearing?

Thanks, LIza

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Liza

#38508

Cover tape tearing | 15 December, 2005

Hi GS,

You mentioned that polystyrene should be sealed by low method. We are currently using the ffg parameters for polystyrene monolayer dull finish carrier tape and AA cover tape. Are these considered low by standard? These are the parameters recommended by the manufacturer.

Temp: 170-180 deg C Pressure: 50-60 psi Dwell Time: 200-600 msec

Thanks, Liza

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Liza

#38509

Cover tape tearing | 15 December, 2005

Hi GS,

I forgot...coming from what you said about aging, the complaints we received come from products that were processed 3-6 months ago. Based on your experiment, should this age affect the quality of the seal?

Thanks a lot, Liza

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GS

#38529

Cover tape tearing | 16 December, 2005

Hi Liza

- polystirene monolayer (blend ?) could be sealed at less presure, ie 35-40 PSI. Temprature could be 165�-170�C.

For sure after sealed you shoud make sure the sealing strength (peel strength)should meet min 15-25 N.(bet avg from 25 to 45 N) Other important point to check is the sealing blades dimention (large) and maintenance of them. If not correct (ie. to sharp or irregular edge)they could damage the sealing results. Have them sealed by using same T&R machine or also tried other T&R machine ?

If well sealed (carrier and cover material, Tape & Reel machine and parameters) and stored (not exposed directly to ligth) they can allow to be used also after 12 months without problms.

Have them tested a multilyers Polystirene? The one we preferred. (less conductive material but more then enough to protect parts against ESD).

Regards...........GS

PS: other infos about Packing (tape and reel) SMC on continuos tapes, see IEC 60286-3 Packing of components for automatic handling

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