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-   -   Hedghog and soldering (https://www.vintage-radio.net/forum/showthread.php?t=153285)

eddie_ce 19th Jan 2019 8:11 pm

Hedghog and soldering
 
Having just received the first batch of ICs and the PCB Frank kindly sent, I have to say that to a senior citizen with still reasonable eye sight the prospect of soldering these multi-legged beasts to the board seems daunting to say the very least.

Does anyone have any hints or guideance on how to go about this?

Many thanks

G4YVM David 19th Jan 2019 9:23 pm

Re: Hedghog and soldering
 
Use sockets

Freya 19th Jan 2019 9:27 pm

Re: Hedghog and soldering
 
Hi Eddie,

I have built quite a few of these and found its easiest to use an alcohol based flux pen, then tack one leg and re check the alignment. If all is well then tack an opposite.
When its in place just work along gradually making sure you top up the flux if need be. If you get a bridge then use solder braid with lots of the alcohol flux and it will remove any excess.

1100 man 19th Jan 2019 9:28 pm

Re: Hedghog and soldering
 
Good Heavens, this sort of surface mount stuff is not supposed to be soldered together by mere Humans! ;D Especially middle aged ones like me with questionable eyesight! I can't even see the pads on one of the IC's on my PCB's :o

I think what you are supposed to do is to apply solder paste to the pads and then stick the components to it. The whole board is then placed in a 'reflow' oven and heated until the solder paste melts. There are plenty of vids on UTube about assembling surface mount stuff.

My own preferred assembly technique is to get someone else to do it!! ;D Which is why I am seriously tempted to buy a complete unit from 'Freya'.
Stephen has, perhaps rather foolishly, offered to supply complete assembled units- I think I will order one before he changes his mind!

Seriously though, it looks a very useful design. While the Aurora is great, I like the flexibility of the Hedgehog. All the selectable options on the front panel make it much more useful especially for fault diagnosis & repair.

Maybe this can become the Hedgehog thread where we can discuss the constructional issues and then our experiences of actually using the thing?

Well done Frank on designing it!

All the best
Nick

60 oldjohn 19th Jan 2019 10:57 pm

Re: Hedghog and soldering
 
Plenty on You Tube, it is actually fairly easy as long as it not too fine a spacing. Remember to brighten the PCB pads with a fibre pen, and wipe with IPA before starting. Then the most important thing to remember is use plenty of flux. With an ordinary soldering iron with lead tin solder.
https://www.youtube.com/watch?v=5uiroWBkdFY
https://www.youtube.com/watch?v=nyele3CIs-U

I would suggest you find an old satellite receiver or computer board and get some thing like this, https://www.ebay.co.uk/itm/ChipQuik-...En9v:rk:6:pf:0 and have fun removing and practice soldering. you will use less than an inch of alloy on each chip and if you save it can be re used. May save ruining a board and if you did have to remove a chip from the main board you have some ready. https://www.youtube.com/watch?v=FhX5059lN6o


John.

FRANK.C 19th Jan 2019 11:23 pm

Re: Hedghog and soldering
 
Don't despair! After all, remember that the PCB was designed by a middle aged mad who isn't exactly hawk eyed so he could build it himself.:)

At first I too was apprehensive about soldering such tiny pins but it is not as bad as it first appears.
The method that Stephen has described is the way that I do it too. There is normally enough solder on the tinned pad to tack the corner pins on temporarily. Just apply flux and heat with the soldering iron.

Liquid flux, solder wick and a metal tweezers make SMD work much easier.
You will probably need some form of magnification to check that the pins are aligned to the pads on the PCB. At first I used a hand magnifier taped to my bench magnifier to gain enough magnification which worked quite well.

I mount the semiconductors first as they are the hardest particularly the video decoder and analogue switch. The rest of the components are relatively easy.

Frank

Lloyd 1985 19th Jan 2019 11:59 pm

Re: Hedghog and soldering
 
I work with 0603 size SMD stuff all day every day at work! Best thing to use is a stereo microscope to look at it with, although I can do it without one. For soldering multi-legged chips, as has been said, line it up, solder one corner pin down, check alignment again, solder the other corner, then get some flux on it and run a blob of solder down one row of pins, do it at a nice steady speed, don’t over-work it as the flux will burn off and you will start bridging legs, of you do bridge a few, it is easy to have another go, and once you are happy with it any remaining bridges can be removed with a bit more flux and a dab of the iron. For SMD caps and resistors you just put a tiny bit of solder on a pad, then stick the component in it, then solder the other end. We have some super-expensive JBC solder tweezers at work, which makes 2 terminal devices dead easy to replace!

I prefer paste flux to the liquid, you can use less of it so it’s easier to clean up afterwards. Once you get the hang of these SMD things, they are quite easy, especially if you have a good iron, plenty of light and a bit of magnification. Oh, keep some solder braid handy too!

Another way I’ve seen putting together of new PCBs done is with solder paste and a hot-plate, especially good if you have a large ground-plane which normally sucks all the heat away from your iron tip.

Regards
Lloyd

G8UWM-MildMartin 20th Jan 2019 2:06 am

Re: Hedghog and soldering
 
In my previous job, we had JBC hot air rework stations (superseding rather unsatisfactory ones using butane cylinders) and some decent flux (smelt like isopropanol) and three effective ways to fit SMDs were:

Soldering iron - Solder opposite corners (22 swg 60/40 multicore solder) then run iron down all pins of one side, adding solder as necessary, until it dropped off the end.

Solder: Tin all pads with solder, much as above, apply flux and IC aligned to less than half a leg out, apply hot air, see solder melt and draw IC into alignment by surface tension.

Solder paste: Dilute slightly with flux, spread over pads, plonk IC on in fair alignment, apply hot air. Tweak alignment using tweezers if necessary. Apply soldering iron (small, pointy tip) to any solder shorts to make them run back up the IC leg.

Replacing ICs was easy: apply hot air until solder melted, remove IC with tweezers and position new one, remove hot air, flood with flux, apply hot air and see solder melt and IC align itself, touch up the odd dry joint with solder applied with the pointy tip to the end of the leg, re-apply hot air to reflow and give a nice smooth finish.

This was just possible by naked eye in my early 40s, but I'd need my "strong" reading glasses to do it 15 years on.

FRANK.C 20th Jan 2019 10:13 am

Re: Hedghog and soldering
 
Quote:

Originally Posted by 60 oldjohn (Post 1112466)
Remember to brighten the PCB pads with a fibre pen

In the case of these PCB's the pads are tinned so unlike bare copper pads there should be no need to clean them with anything abrasive. If they have been handled a lot a wipe with IPA to get rid of and finger grease should be all that is needed.

The smallest pin pitch on the IC's is 0.5 mm. All passive components are 0805 size which are relative easy to mount. In fact when you get used to them you can mount them quicker that through hole components.

Frank

Freya 20th Jan 2019 11:00 am

Re: Hedghog and soldering
 
Quote:

Originally Posted by Lloyd 1985 (Post 1112478)
I prefer paste flux to the liquid, you can use less of it so itís easier to clean up afterwards. Regards
Lloyd

The alcohol based flux pens do not need any clean up.

FRANK.C 20th Jan 2019 11:07 am

Re: Hedghog and soldering
 
5 Attachment(s)
Some photos of the PCB

HamishBoxer 20th Jan 2019 4:43 pm

Re: Hedghog and soldering
 
Not too difficult to solder using the must have head magnifier.

merlinmaxwell 20th Jan 2019 5:28 pm

Re: Hedghog and soldering
 
Quote:

using the must have head magnifier.
I use some +3.5 reading glasses from Poundland sometimes in series with a +2 pair for really small work.

bluepilot 20th Jan 2019 6:49 pm

Re: Hedghog and soldering
 
Someone I knew used to solder these things by applying solder paste, placing the components and then putting the board in an oven with a temperature set above the solder melting point. When the solder melted he took the board out and let it cool down. He insisted it worked although I never tried it myself.

rambo1152 20th Jan 2019 11:33 pm

Re: Hedghog and soldering
 
Quote:

Originally Posted by merlinmaxwell (Post 1112700)
Quote:

using the must have head magnifier.
I use some +3.5 reading glasses from Poundland sometimes in series with a +2 pair for really small work.

My wife reckons it's not a good look, but I'm glad it's not just me who does that.

60 oldjohn 21st Jan 2019 10:15 am

Re: Hedghog and soldering
 
I would not be without my magnifier light, oh and an aerosol of anti mist spray.


John.

1100 man 28th Jan 2019 10:17 pm

Re: Hedghog and soldering
 
Hi Frank,
I assume you deigned the PCB yourself? If so, do you have the file to create the stencil for the solder paste?
I've been discussing with a friend about actually reflowing the boards in an oven or hot plate, rather than hand soldering them.

All the best
Nick

FRANK.C 28th Jan 2019 11:28 pm

Re: Hedghog and soldering
 
Hi Nick
I have never tried to ordered a stencil. But I believe that the Gerber Files for it, which can be downloaded from the Hedghog web page contains all the information required.

I checked on PCBWay.com and when ordered with PCB's a stencil that would do both sides would cost about US $ 22 extra. This includes the extra postage.
Or purchased on it's own costs US $ 36 including postage to Ireland.

Frank

G8UWM-MildMartin 29th Jan 2019 12:40 am

Re: Hedghog and soldering
 
Quote:

Originally Posted by FRANK.C (Post 1112534)
Quote:

Originally Posted by 60 oldjohn (Post 1112466)
Remember to brighten the PCB pads with a fibre pen

In the case of these PCB's the pads are tinned so unlike bare copper pads there should be no need to clean them with anything abrasive. If they have been handled a lot a wipe with IPA to get rid of and finger grease should be all that is needed.

The smallest pin pitch on the IC's is 0.5 mm. All passive components are 0805 size which are relative easy to mount. In fact when you get used to them you can mount them quicker that through hole components.

Frank

Yep, 0.5mm pitch is very fair game for hand-soldering!

Semir_DE 3rd Feb 2019 12:05 am

Re: Hedghog and soldering
 
1 Attachment(s)
Hi everybody,

Today I have started to assemble the Hedghog board. I find it very well laid out and the part references make it easy to place the parts. I have printed out the component list and component layout and mark off every part that I have already soldered to the board.

In order to make the work flow efficient I usually mount all parts of the same value at once e.g. all 47kΩ resistors then all 10kΩ resistors etc. For this method it would be helpful to have a parts list that is sorted by part values instead of part references. I wonder if Frank could be kind enough to provide such a list? I would do it myself but I would need the excel version of it as I can not sort the pdf...


Semir


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