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Surface Mount practitioners?


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I'm looking for someone that is comfortable soldering the tiny surface mount components, preferably in Melbourne but not exclusively.  even with magnifiers and following the online videos, these things are quite the challenge. 

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They can be a challenge when they happen to be in between other, much larger and taller components.

If you want to have them perfectly placed, get a tiniest amount of glue to hold them perfectly in place.

Then get your thin tipped soldering iron and place it for 2 seconds in such a way, that it heats up both the component and solder pad.

Then just a dab of solder and you are done.

After you do 10, you'll be an expert (in easy access surface mount soldering).

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Thanks for your reply Rockeater,

 

I can handle the smaller resistors without too much trouble (apart from going 'cross-eyed!) but these miniature ICs are a real PIA - I've looked at numerous videos about smearing paste on the copper and positioning the IC on top of that and cooking it in an oven at 150*C for 15 minutes but somehow, the damn things just don't seem to pull straight onto the pads like they say so I've assumed it's the silly bugger attempting things well beyond his capabilities (much as i hate to say it) and looking for someone who has mastered 'the knack'.

 

I'll try getting some cheap no-name small 8 pin tiny ICs and some bare 'learning' pcbs and try it again - possibly need a very small tip on the cheap temp controlled iron I got for this too - hmmn ...

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2 hours ago, HdB said:

I'll try getting some cheap no-name small 8 pin tiny ICs and some bare 'learning' pcbs and try it again

Well, for the 8 pin or so, start with pre-tinning of the 8 lands on the board.

Then get fresh solder wick and clean any excess solder from them.

Then glue the chip onto the board and just solder quickly all of the pins with normal iron (or heat variety) without bothering about shorting pins.

Then grab that solder wick again and remove the shorts and check with multimeter that:

1. there are no shorts between the pins

2. the pins of the IC actually connect to the tracks (measure on some other components to which track go)

It is best to use very hot iron for short periods of time than a cool one for long periods.

Putting stuff in the oven with 150 degrees will never solder anything. When de-soldering, I use 400 degrees and never exceed 2 seconds on the component. Do not know what the temp is used during soldering because my iron does not have temp control. A standard 30 year old Weller it is.

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Roman's advice is good,   I always use a magnifying lens , and a well lit area.  Do you know the part numbers on the i'c's , ? I am good with doing SOIC size , and TSOP if that helps, but located across the ditch so to speak. 

 

 

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Thanks guys for you advice,

 

Yeah, I wondered about that stupidly low 150*C and measured the temp of the pcb when inside and it came to about 260, or thereabouts - go figure -  I got one of those infra-red 'toaster-ovens' just for the job too! 

 

I've taken note of the tips about pre-coating the copper and the solderwick cleaning, Roman too.

 

Yeah, my old weller, excellent iron with quite sharp #7 tips finally gave up the ghost and I got one of those new temp controlled ones and a cheap lower power 'toys' with the temp setting in the handle - it seems to work okay given the cheap price surprisingly and it worked okay for this "smd dunce" for the small legs on those remarkable little dual fets (SQJB00EP-1) - probably need a high quality new iron for any more work with the tiny IC components, including the resistors.

 

Ah, thanks Chris  - most appreciated - the chips are those synchronous rectifiers LT4320 in the extremely small DFN8 surface mount version - I stupidly ordered a couple of the LT4320 IDD version with just little dots instead of legs and the miniature size - they were about A$8+ where the thru hole version LT4320HN8 in the pdip8 are the normal 8 pin size but about A$13 ea - saved a few $s but got a headache instead!

 

I'm still playing around with these things to get a "better" rectification than the normal Schottky diodes and they can work up to about 70 volts AC, and with higher voltage TO220 fets (like the STP110N8F6, for example and they don't even get warm) they can find use in higher power amps too. 

 

Do they make any difference to the sound?  In my humble opinion, yes they do - they seem to produce what I would call  a quieter, more detailed sound yet having more 'grunt' - not so sure about the class AB amplifiers with their inherent higher PSRR, etc but it does make good sense to produce a better dc supply to begin with, if possible, and they certainly do just that.  

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