Author Topic: Hand solder LGA16?  (Read 1158 times)

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Offline RogerThatTopic starter

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Hand solder LGA16?
« on: November 11, 2019, 08:39:56 pm »
Hi,

So, I have a board which uses a LIS344 accelerometer. This is a LGA16 package and I'm having some trouble to reliably solder this.

I have tried two different foot print. One, where the solder pads extend outside the package to be able to solder using the normal soldering iron. Then, a second where I made the footprint exactly as the pads (I made a small mistake, ST recommends a footprint which is +0.1mm x and y to the pads).

The last footprint seams to solder nicely, the component re-align it self when the solder starts flowing(using hot-air on the opposite side of the board). But, the connections are not good, I usually end up with just one output working while the others seams to be froozen.

Anyone have any suggestions?
 

Offline SiliconWizard

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Re: Hand solder LGA16?
« Reply #1 on: November 11, 2019, 09:07:54 pm »
Pre-tin the IC pads, it helps a lot (not too much solder though!)
 
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Offline Shock

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Re: Hand solder LGA16?
« Reply #2 on: November 11, 2019, 09:18:05 pm »
What exact preparation are you doing for reflow? Are you using paste or pretinning, using flux at all? Are you using too much solder or not enough? To add what SiliconWizard said tin both clean and then use flux.
Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 189, 87V, 117, 112   >>> WANTED STUFF <<<
Oszilloskopen: Lecroy 9314, Phillips PM3065, Tektronix 2215a, 314
 

Offline RogerThatTopic starter

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Re: Hand solder LGA16?
« Reply #3 on: November 11, 2019, 09:25:18 pm »
I've pre-tinned and added flux ( a combination of flux and tin which I know works very well together). I've tried different amount of tin also, from flat to small 'hill'. Both on the component and pad. I usually don't clean between the tinning and adding new flux, can this make a difference?
 

Offline DaJMasta

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Re: Hand solder LGA16?
« Reply #4 on: November 11, 2019, 10:16:22 pm »
Have you tried with paste?  Pretinned and then just a small dab of solder paste will give you a bit of extra material, but it will be physically sticking up and malleable, so it could aid with reflow.

That said, I'd think pretinned on the IC itself and ample flux would do a pretty good job - is there a substantial connection to the ground plane, perhaps?  If the board underneath isn't reaching soldering temperature because it's wicking away too much heat or has too much thermal mass, when the solder on the IC pads melts, it may just not want to stick to the cooler pads.  If this is the case, preheating the board could help.
 

Offline Shock

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Re: Hand solder LGA16?
« Reply #5 on: November 11, 2019, 10:22:12 pm »
Cleaning removes flux and rubbish like displaced oxides and contaminants. Cleaning your solder wire and your tip well can also improve joint quality and wetting, everything counts especially while troubleshooting.

Don't use too much flux either and read this, which is the next thing are you allowing adequate dwell time. Consider also that it might not be a soldering issue. https://www.all-spec.com/no-clean-flux-activation
Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 189, 87V, 117, 112   >>> WANTED STUFF <<<
Oszilloskopen: Lecroy 9314, Phillips PM3065, Tektronix 2215a, 314
 


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