Author Topic: Strips of tape on PCBs in products, what for?  (Read 708 times)

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Offline lpc32

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Strips of tape on PCBs in products, what for?
« on: February 06, 2021, 10:47:55 pm »
Inside end products you sometimes see tapes placed on the PCB in specific areas or on specific components.

Like the motherboards below. It's not completely consistent (maybe some was peeled off), but there are two commonalities: on the heatsink retention brackets, and on the flash chip at the lower right.

What's it good for? And why different types of tape?



 

Offline bson

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Re: Strips of tape on PCBs in products, what for?
« Reply #1 on: February 07, 2021, 11:04:27 pm »
Perhaps it's to protect edges from chafing during shipping?
 

Online wraper

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Re: Strips of tape on PCBs in products, what for?
« Reply #2 on: February 07, 2021, 11:17:33 pm »
When tape is used originally in laptops, it's to protect something from short circuit, to hold something in place, or to protect FPC cables from rubbing against something. Also Kapton tape is often used on SMT connectors so pick and place machine can hold them.  Examples on photos are strange. Maybe it's used to hold metal brackets in place and prevent from falling out. If they they were removed previously, say for repair purposes, original adhesive tape under them may become weak.
 

Offline S. Petrukhin

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Re: Strips of tape on PCBs in products, what for?
« Reply #3 on: February 10, 2021, 12:11:30 pm »
I think this is a common designer's jamb and a safety net against unnecessary contact with the body. Maybe even to prevent the sound and the occurrence of resonance.
And sorry for my English.
 

Offline bson

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Re: Strips of tape on PCBs in products, what for?
« Reply #4 on: February 10, 2021, 09:03:14 pm »
Another guess might be that it's for easy visual identification since the boards are populated slightly differently.  I.e., different variants get slightly differently placed tape strips.  The tape should be visible even through a plastic bag or pouch.
 

Offline lpc32

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Re: Strips of tape on PCBs in products, what for?
« Reply #5 on: February 10, 2021, 10:09:56 pm »
I sort of expected this to be standard practice of some sort, and someone would just pop in and tell from experience what it is. Surprisingly that wasn't the case.

@bson, Edges of something on the case side, opposing the moterhboard brackets?

Relying on tape for short circuit protection - won't that be bad design?
And at least the flash in the lower-right corner isn't conductive.

To hold the brackets (during assembly?) - the vertical pieces of tape in images 1 and 2 might fit the bill, but not exactly the one in image 3, nor the horizontal ones.

Resonance - Won't it work better with a rubbery padded material?
(Maybe that's what the things in image 1 are, next to the three top screw holes.)

Identification - Seems complex. Won't it be simpler to tag with different colors?
 

Offline Niklas

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Re: Strips of tape on PCBs in products, what for?
« Reply #6 on: February 10, 2021, 10:43:39 pm »
wrapper was right about keeping the metal part in place.
That metal piece is the counterpart for the screws that holds the heats pipe towards the CPU on the opposite side of the board. Have a look between 12 and 18 minutes in this video of someone taking that laptop apart:
 

Offline lpc32

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Re: Strips of tape on PCBs in products, what for?
« Reply #7 on: February 14, 2021, 01:11:22 pm »
That metal piece is the counterpart for the screws that holds the heats pipe

Of course it's the heatsink brackets, but that video doesn't provide new evidence why the tape's there. :)

One thing about the motherboard on that video, if I can see right, is that there's no tape on the flash chip in the corner.

 


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