UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Hints, Tips and Solutions (Do NOT post requests for help here)

Notices

Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

Closed Thread
 
Thread Tools
Old 14th Jan 2015, 12:26 am   #1
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
Default Repairing Printed Circuit Boards which use Surface Mount Technology.

I do SMT work on proto RF boards on almost a daily basis.

Most people have too much basic tremor to do this sort of thing without acquiring a few skills:

1) Forget bench magnifiers and those 'Mantis' things. The whole thing shakes and vibrates.
2) Go for a stereo microscope on a very solid stand. you don't want too much magnification. A large objective with plenty of light capturing area helps. My favourite is a Russian job which cost £200 new. I prefer it to my Zeiss and Leitz scopes.
3) Forget pliers. Tweezers are in, and no two folk pick the same style, so you have to try several before you settle on what works for you.
4) Forget TCP1a or Antexes, or Henley Solons. You need a soldering iron where you grip it only an inch from the business end. Look at a Metcal.

You develop a technique where your forearms and much of your hands rest on your bench and you move the position of your iron, tweezers and solder by rolling your points of contact. It gives you a tactile position reference and it gears down your muscle to movement ratios.

It's like the difference in trying to be precise stick-welding with an long, new rod compared to a really dinky TIG torch. Just having a go with the right tackle and getting your technique going makes a dramatic difference.

David.
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

Last edited by Station X; 15th Jan 2015 at 10:02 pm. Reason: Post copied from another thread.
Radio Wrangler is offline  
Old 19th Jan 2015, 6:52 pm   #2
Wendymott
Octode
 
Wendymott's Avatar
 
Join Date: Jun 2013
Location: Huddersfield, West Yorkshire, UK.
Posts: 1,782
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

Hi David.. What size devices are you down to now ?? I used to use 1210's but have now started stocking 0805........... that's small enough for me...... I still use a TCP1 iron with a fine tip , but I'm just playing at it.....I have some really fine tweezers and are indispensable. I do like using SMD's as they are a good solution at times, especially for small pcb's.
__________________
Should get out more.

Regards
Wendy G8BZY
Wendymott is offline  
Old 19th Jan 2015, 7:09 pm   #3
_Clint_
Pentode
 
Join Date: Mar 2011
Location: Sevenoaks, Kent, UK.
Posts: 101
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

If you are doing a fair bit of SMD work, I would like to add these to your must have list.

Firstly Multimeter tweezers, one hand testing of a multitude of components, very fast to use.

Secondly more tweezers but very hot ones in the way of soldering equipment.

Thirdly some hot air with a fine tip.

This combo has saved me tons of time.
Attached Thumbnails
Click image for larger version

Name:	IMG_2442.jpg
Views:	284
Size:	96.7 KB
ID:	102921   Click image for larger version

Name:	IMG_2441.jpg
Views:	291
Size:	43.2 KB
ID:	102922   Click image for larger version

Name:	IMG_2443.jpg
Views:	282
Size:	63.4 KB
ID:	102923  
__________________
If it sparks, it was either meant to spark, or something is wrong, very very wrong.
_Clint_ is offline  
Old 19th Jan 2015, 7:17 pm   #4
Guest
Guest
 
Posts: n/a
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

I have used 0402, quite small but doable by hand. For one circuit, where the components were on the wrong side, we had to hand solder 0201 components so they didn't stick up into the keypad moulding too much. That was 'fun'. BGA (ball grid array) by hand is even more entertaining. I have the thought that if a machine in China can do it, so can I.
 
Old 19th Jan 2015, 7:48 pm   #5
Lloyd 1985
Nonode
 
Lloyd 1985's Avatar
 
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,814
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

I've been working with SMD stuff and BGA since I left college over 10 years ago, I used to repair mobile phone's to component level, great fun!! I once was removing one of the big BGA chips from a Nokia 8310 (the tiny phone they made back then!) using a hot air rework gun, and inadvertently flicked it with the tweezers once the solder had melted... It pinged across the board taking loads of other tiny SMD caps and resistors with it... I sat for the whole day rebuilding the damn thing! Ordering individual resistors and caps from stores to make sure I got the right ones. Once I'd finished I was quite surprised to find it worked!

Now I work with bigger SMD stuff, and quite like using the hot air soldering gun, although it's useless for the big surface mounted voltage regulator's we use with large ground planes hidden in the boards. I'm also quite happy without any magnifiers, I find they just get in the way, and give me a headache after looking through them for any length of time.

Regards,
Lloyd
Lloyd 1985 is offline  
Old 19th Jan 2015, 8:03 pm   #6
dseymo1
Retired Dormant Member
 
Join Date: Dec 2007
Location: Shropshire, UK.
Posts: 3,051
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

I try and avoid SMDs, but when I have to tackle them I have a little manual suction handler with a range of suction pads. Very simple and effective.
dseymo1 is offline  
Old 19th Jan 2015, 8:23 pm   #7
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

I've gone down to 0402 on PCB, and a bit smaller on alumina.

Clint's suggestions are good. I have connection tweezers like his picture attached to a Peak Instruments LCR meter. Very necessary to identify unmarked components.

I keep a post-it page upside down and use the tacky surface to anchor parts from sneezes etc. You can also write values and draw arrows to the bits.

Re hot tweezers, I sometimes use the firm's hot tweezers, they're quite good, but I'm ambidextrous and I use a pair of Metcals (acquired dead and fixed) usually one in each hand sometimes like chopsticks. This gives me a lot more power than the metcal tweezers and I can mix tips and don't need other tips than the soldering ones. This is an expensive way to do it if you had to buy new irons and bases, and not everyone can juggle two at once.

I am going to HAVE to get a hot air machine. I do miss having the use of one. We had one of those cheapie Chinese ones at work, but the power was poor compared to the "Pace" I'd used before. People left it on, melted its handle and then dropped it. In its death throes it used to blow out bits of broken glass a bit like fragments of test-tube.

I'm quite happy changing 240 pin quad-fine-pitch ICs and I sometimes use a heat gun for pads-undereath devices, but I want a good hot air machine before touching BGAs. I have compressed air in the garage, so I should look for a surplus industrial job. Need for compressed air puts a lot of people off.

Cheers
David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline  
Old 19th Jan 2015, 9:11 pm   #8
kellys_eye
Octode
 
Join Date: Jan 2014
Location: Oban, Scotland, UK.
Posts: 1,118
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

Quote:
Originally Posted by Radio Wrangler View Post
I keep a post-it page upside down and use the tacky surface to anchor parts from sneezes etc. You can also write values and draw arrows to the bits.
A very useful tip - thanks for that!
kellys_eye is offline  
Old 19th Jan 2015, 10:12 pm   #9
cmjones01
Nonode
 
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

Another tip I've used for removing and refitting big surface-mount devices - not just chips with lots of pins but chunky transistors and the like - is to pre-heat the PCB from underneath. I use an upturned aluminium power resistor (50W or so) connected to a bench power supply. Warming the relevant area of the board up to 50-70C makes a big difference to the ease of removing parts, especially if there are big ground planes involved. I noticed that super-expensive Ersa IR rework machine had this feature, so I tried a cheap-and-cheerful version with the power resistor and found it worked well!

I've used this technique with a horrible cheap Chinese hot-air gun (it works if you bang it on the bench hard enough) to remove and refit BGAs successfully.

Chris
__________________
What's going on in the workshop? http://martin-jones.com/
cmjones01 is offline  
Old 19th Jan 2015, 10:53 pm   #10
Outrun_uk
Heptode
 
Join Date: Aug 2009
Location: Liverpool, Merseyside, UK.
Posts: 704
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

I deal with SMT on a daily basis. As David says in post #1 a good microscope and iron are essential. I have a stereo microscope, plenty of light, Metcal iron with various size tips. Also flux is your friend here, I use liquid no-clean variety from a dispensing bottle with needle tip.

Plenty of practice on scrap boards is a good idea, drag soldering multipin devices takes a bit of practice but once you get the technique it becomes easier. Hot air stations can be picked up cheaply these days which are good for removing components but beware of having the airflow too high, easy to blow smaller parts clean off the board!. Larger QFP's can be a problem with hotair but ChipQuik is good stuff albeit fairly pricey.

Clean up with IPA or Fluxclene and a cheap USB pen-style microscope is great for final inspection.

JM2PW

Kev
Outrun_uk is offline  
Old 20th Jan 2015, 5:34 pm   #11
Anthony Thomas
Hexode
 
Join Date: Jan 2013
Location: Ålesund, Norway
Posts: 361
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

Thanks to David for posting this, I particularly liked the advice on the soldering iron that certainly made sense.

Last edited by Anthony Thomas; 20th Jan 2015 at 5:35 pm. Reason: spelling.
Anthony Thomas is offline  
Old 22nd Mar 2015, 11:33 pm   #12
FrankB
Heptode
 
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 663
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

My friend who was a computer tech had great luck in repairing the BGA chips on mother boards by using- of all things- a hair dryer or a heat gun
He could manage to re-heat the BGA chip enough that the solder would reflow.
Like he told me-" if it works, I saved the board. If not, I replace the board."
The company he used to work for was too cheap to get the proper equipment.
FrankB is offline  
Old 29th Mar 2015, 2:17 pm   #13
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

Hi David, I'm just interested, do you 'make a living' out of repairing modern SMT based products? I thought the general view in the trade was to either swap the board/assembly or junk the unit? I mean, all that equipment you mention must represent a considerable financial investment? At a time when due to the relatively low replacement cost of most consumer goods, the ability to charge a realistic repair fee based on time taken and investment on specialist equipment, is very difficult? It's obviously up to the individual what they charge, but when you see the hourly rate of garages (apparently £75 p/h average), and in all honesty the knowledge and technical ability level that you have must surely be greater, then can you charge say £150 for two hours work on say a DVD player that the consumer could replace for £40? I'm not trying to throw a spanner in the works, it just annoys me that well qualified, able, honest electronics engineers are simply unable to charge a fair rate for their repair work due to the cost of consumer goods and their 'unrepairability' due to miniaturisation, SMT etc. There's no more graphic proof that this is the case that the demise of 'Television' magazine. Even though they expanded the scope of the magazine to include a wider range of domestic goods, the demise of the domestic electronics repair engineer meant ever dwindling sales of the mag. In short, I just don't 'get' the feasibility of repairing modern SMT goods down to component level, although I take my hat off to you and I'm in awe of your ability and resolve!
__________________
A digital radio is the latest thing, but a vintage wireless is forever..

Last edited by AC/HL; 29th Mar 2015 at 3:52 pm. Reason: Off topic aside removed
stevehertz is offline  
Old 29th Mar 2015, 3:56 pm   #14
AC/HL
Dekatron
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

There are people who repair those BGA chips in games machines, but that's a focussed and fairly common problem. I tried with a PS3, but gave up in the end.
AC/HL is offline  
Old 29th Mar 2015, 5:38 pm   #15
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

Hi Steve,

I design Radar and radio equipment for use in aircraft, so the gear I work on is a bit more expensive than the usual consumer stuff, but price isn't the point. Before that I used to design spectrum analysers and such like at HP. If you come across the Agilent Noise Figure analyser, that's one of mine along with the matching noise sources.

I work mostly with prototypes, and they are in short supply. If anything goes wrong, it gets fixed for two reasons:

1) I want to know what failed and why. Reliability is very important and only by fault-finding down to component level can all the information be harvested. Repairing the board and getting it going again to full specification is a good proof that the diagnosis was good.

2) We need all our prototypes, they all go through rather tough formal tests for airworthiness certification for European and American approvals, and then the FCC have a pile of tests. Not having as many units as planned throws the whole plan into havoc.

Some of the SMT work is performing modifications to investigate design changes. Sometimes it amounts to building small add-on dead-bug breadboard sections on existing PCBs quicker than a board can be turned to see if it is worth laying out and building new boards.

If any units fail out in the field, they are fault-found down to component level in order to understand what has gone wrong. Maybe the board gets fixed, maybe it is just swapped as a matter of economics, but only once the fault is understood.

So I make a living out of design work. Testing, prototyping, modifying are important adjuncts.

Awe? I don't do anything I don't firmly believe just about anyone else could do. It might take a bit of reading, thinking, practicing, but that's how I did it and I'm not special in any way. so just about anyone else ought to be able to do the same or more.

If something looks difficult, it probably is. So I spend a while looking at it from different directions until I stumble upon one which makes it look easy, and voila! it *is* easy! Everything is easy once you've sussed it.

If you tell yourself you can't do something, you are never disappointed
If you try to do something you are often surprised.

This group harbours people from all walks of life, doing amazing things. The total amount of knowledge washing around is staggering.

And I miss Television magazine, and the old Wireless World, and.... and....

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

Last edited by Brian R Pateman; 30th Mar 2015 at 6:02 am. Reason: Automotive aside removed. Off topic for the forum.
Radio Wrangler is offline  
Old 30th Mar 2015, 12:04 am   #16
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,316
Default Re: Repairing Printed Circuit Boards which use Surface Mount Technology.

On Friday I had a look at the non-working extractor fan from my son's newly-acquired flat. The printed circuit board was all SMDs except for a couple of electrolytics and two pots. The culprit seemed to be the Triac that switched the motor on and off: it had a large hole burnt in the plastic casing. Before ordering a replacement I checked out the motor and found it open circuit, with signs of severe overheating, so not repairable after all. The Triac, a 1A rated power device, was relatively large and was about the only SMD component that looked simple enough to remove using my 15W Antex with its smallest bit had it been the only fault.

I can confirm the effectiveness of the "rolling your points of contact" technique (post #1). In the 1970's I was involved in custom IC design, the chips being packaged in the original SMD packages: the military flat pack with joggled legs on a 0.050" pitch. I used a Leitz microscope to inspect and probe test the prototype wafers. With the aid of the microscope, I did once manage to write (not print) my name on one of the aluminium interconnects of a duff chip using only a pin held between index finger and thumb, the heel of my hand being pressed firmly into the table surface. Process resolution limitations meant that interconnects were wider then.

Last edited by AC/HL; 30th Mar 2015 at 1:41 am. Reason: Please use the PM system for non-Forum replies.
emeritus is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 6:32 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.