VCC and GND shorted on a module device. Static?

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#1
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Hi All

 

I was preparing a PCB by soldering the components . There is a LGA module which i also manged soldered.

 

Before powering the PCB, i always check that the VCC and GND are no shorts. 

 

On this particular PCB i noticed the VCC and GND was shorted.

 

Therefore i removed the LGA module to check the PAD below it. 

 

After some investigation i found the VCC on the actual module is shorted to GND, but there is nothing on the pads. It seems like it something internal.

 

Has anyone else experience such issue similar to mine? This is first time this has happened. 

 

Can static do similar issues?

 

Thanks

 

 

Thanks

Regards

DJ

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No, it was not static, (or at least is extremely unlikely).  MUCH more likely is you measured with the meter polarity reversed.

 

What happens when you measure another one of these modules? 

 

Are you sure of which "pin" is which?  Part flipping and rotation can make you very dizzy.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Depends on what you determine to be 'shorted'. There is very low resistance (< 1ohm) and high resistance (> 1 Ohm). Measuring this can give an insight in the kind of short circuit and maybe the likely cause. Usually very low Ohm shorts are soldering, pcb etch problems or maybe a capacitor. Static damage usually causes a more resistive problem.

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djoshi wrote:
i also manged soldered
Warning: Poor joke ahead!

 

Is that meant to be "mangled" or "managed"?

Ross McKenzie ValuSoft Melbourne Australia

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avrcandies wrote:

No, it was not static, (or at least is extremely unlikely).  MUCH more likely is you measured with the meter polarity reversed.

 

What happens when you measure another one of these modules? 

 

Are you sure of which "pin" is which?  Part flipping and rotation can make you very dizzy.

 

When we measure other boards, the resistance is is few hundred ohms.  While on this board it is 0 ohms, 

When the module is flipped i am sure it is the right pins.

Thanks

Regards

DJ

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Kartman wrote:

Depends on what you determine to be 'shorted'. There is very low resistance (< 1ohm) and high resistance (> 1 Ohm). Measuring this can give an insight in the kind of short circuit and maybe the likely cause. Usually very low Ohm shorts are soldering, pcb etch problems or maybe a capacitor. Static damage usually causes a more resistive problem.

 

Maybe its faulty module to begin with.

 

 

Thanks

Regards

DJ

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It's more likely you damaged the module during soldering or desoldering...trashcan it & see if it happens again.

 

Is your soldering machinery operating under a verified process? 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Sun. Mar 8, 2020 - 04:41 PM
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I am using hot air and hot plate re work station from Aoyue. Maybe i could have applied hot air onto the board or near by components much longer then i should have.

 

 

Thanks

Regards

DJ

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I am using hot air and hot plate 

For parts like that, you should probably be using an actual multizone reflow oven, with a tightly controlled temperature profile.  This is not an 0805 resistor!

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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I know, i wanted to check my design was working before paying for some boards to be assembled by another company.

 

Are there any small scale ovens  for prototypes that are recommended? 

Thanks

Regards

DJ

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A lot of people build their own

 

I know of several people who have built the controleo oven.  In fact, i have a kit , but haven't built it yet

   https://sites.google.com/site/markscontroleo2build/

 

https://whizoo.com/reflowoven

 

Of course, if you have the $$$ just buy an oven

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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djoshi wrote:
There is a LGA module which i also manged soldered.

LGA's are not soldered, but rather are placed into a socket???

 

BGA'a are soldered!  And very difficult to do by hand!

 

Jim

 

 

(Possum Lodge oath) Quando omni flunkus, moritati.

"I thought growing old would take longer"

 

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This the LGA that is being used:

https://www.quectel.com/product/bg96.htm

 

Thanks

Regards

DJ

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you have not accidentally crossed the probes and are now measuring the protection diodes right?

 

i would not expect a module like that to already be a fail out of the box. So something has happened.

you could have indeed overheated it.