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To tin or not to tin — Parallax Forums

To tin or not to tin

ElectronegativityElectronegativity Posts: 311
edited 2005-10-05 00:39 in General Discussion
Hello, I just bought one of those Pulsar home PC board kits.

I know several people who frequent this forum have used these successfully, and I am wondering if you "Tin" the boards or not.

Does it make a difference?

If so, then what product would you reccomend?

Thanks,
-Alexander

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I wonder if this wire is hot...

Comments

  • steve_bsteve_b Posts: 1,563
    edited 2005-10-03 12:23
    I haven't used this board...but in general, tinning makes it easier to solder to your board.

    I don't see a bad reason for using this....but I'll let others chime in!

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • SN96SN96 Posts: 318
    edited 2005-10-03 12:30
    Tinning helps reflow. With out tinning you can get non-wetting problems or dewetting. If you plan to hand solder the whole thing you could get by without tinning I suppose. Keep in mind though there may be some components where the solder will a bit stubborn and my not want to reflow well.

    I have worked primarily with SN96 solders that has a melting point of 700 Deg. Tinning is much more critical when using high temp solders. SN63 is more the type of solder alloy you will be working with which reflows much better. HMP solders are the hardest to reflow and at 800 degrees melting point, if you don't get it right fast you can quickly burn up the component and even the board·as well!

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    Mike

    --
    Formally RoboROOKIE.


    Post Edited (SN96) : 10/3/2005 4:13:37 PM GMT
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-10-03 13:30
    I have built a few boards as the solution for tinning is not locally available.

    Being that I live in a steel making town, the atmosphere is highly corrosive.· So what happens is that a copper board goes from being shinny and fresh to a blacken mess in a short time period.

    So, it is really a good idea to tin your boards as they store easily and when you get ready to solder you don't have to scrub off a layer of tarnished copper in order to get a good flow.

    Additionally, having that protective layer of tin tends to avoid excessive soldering.· I have tried to tin the whole board with a soldering iron, but it is both tedious and wasteful.

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    G. Herzog in Taiwan
  • SN96SN96 Posts: 318
    edited 2005-10-03 16:18
    Very good point Kramer. Oxidation can be your worst nightmare.

    If your board is not to large, you can hand tin your pads. I hand tin several small boards that are not worth the time and prep of waving especially if it only has two SMT parts on it.


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    Mike

    --
    Formally RoboROOKIE.
    ·
  • ElectronegativityElectronegativity Posts: 311
    edited 2005-10-03 16:24
    That sounds like a good idea.

    If I hand tin the pads for the SMD components I should be able to hold them down with a tweezer and heat the feet instead of bringing the solder to the heated joint.

    I destroyed 3 SX20's this weekend trying to attach them to Sparkfun breakout boards because I globbed on too much solder and bridged accross the pins. Attempts to desolder ended up damaging the fine traces on the boards.

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    I wonder if this wire is hot...
  • steve_bsteve_b Posts: 1,563
    edited 2005-10-03 16:57
    E....look in to chip carriers instead of soldering the chip directly. Then if you ever have to replace the SX (hopefully never) you can just pull the chip out and put a new one in...rather than desoldering all over again!

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • ElectronegativityElectronegativity Posts: 311
    edited 2005-10-03 17:05
    Hi Steve.

    I do that for DIP stuff but don't know of any chip carriers that would take as SX20.

    Do you?

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    I wonder if this wire is hot...
  • SN96SN96 Posts: 318
    edited 2005-10-03 17:12
    The trick to soldering fine pitch components such as a QFP is to "tac" two opposing corners before soldering the rest of the leads. When you have one lead tacked, you can move the QFP in position while holding the soldering iron on the pad (with the solder) allowing the component to be moved. when you have got all the pins ligned up, remove the soldering iorn from the pad that has the solder, and it will almost instantly "freez" in to position. Each position attempt should only be 1 second. Allow the joint to cool and try again. You do not want to hold the solder tip on the pad for a long time. Once you have all pins lined up on the pads, you can proceed to tack the other corner of the part.·I wish I could show you a video how I solder these parts but my work would not appreciate it.

    Also, any solder bridges can be removed using the iron but a bottle of flux makes this much easier. The next best thing is to use a solder wick; a copper braided wire. You can even use a piece of striped copper stranded wire, twist it tightly, and then use that to suck any excess solder if you do not have any solder wick.

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    Mike

    --
    Formally RoboROOKIE.
    ·
  • ElectronegativityElectronegativity Posts: 311
    edited 2005-10-03 17:21
    I appreciate the advice SN96.

    Do you think pre-tinning the pads would place enough solder to attach a component without adding more later?

    Also, why do you use such high temperature solder?

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    I wonder if this wire is hot...
  • steve_bsteve_b Posts: 1,563
    edited 2005-10-03 17:55
    E.

    when I solder most things together (specifically connectors and wires) I tin the wire ( in some cases) and the connector I'm going to (just with a tiny bit of soldeR).
    This means when I put the two together, the iron only has to melt the solder (which is at a lower melting point than the hardware materials), not heat both connector and wire to accept solder and then fuse together.
    Basically, you're seeding both components so that their like parts (the solder) will easily melt together.

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • SN96SN96 Posts: 318
    edited 2005-10-03 18:08
    Yes, you can for example place a small dome of solder on 1206 pads and simply place the 1206 resistor on the pad and using two soldering irons "hit" the pads at the same time. Like magic the SMD resistor is pulled in to near perfect alignment as it reflows, with out adding any additional solder.

    For me, parts with ic's, I hand reflow solder on the pads, and then I use a solder wick to remove the "dome" of solder. I like all my pads flat to allow precision alignment of the ic pins. I would not try to hand solder an ic with solder already on the pad because this makes lining up the ic harder. By adding solder and then removing it with a solder wick will provide the right amount if "tin”. If you are going to store the board for later use, you can leave the solder on thick until you are ready to put on your parts.

    Why Such High Temp Solder?


    At my work we manufacture drilling equipment for oil wells. These drill bits that contain our electronics under go extreme vibration and heat. We use special ic components that are made out of ceramic to survive extreme temperatures, which is why we use hi temp solders. I personally would use sn63 on my own projects as·low temp solder reflows so well.

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    Mike

    --
    Formally RoboROOKIE.


    Post Edited (SN96) : 10/3/2005 6:11:17 PM GMT
  • ElectronegativityElectronegativity Posts: 311
    edited 2005-10-03 18:19
    Two soldering irons!

    I've been spending so much on toys lately that I have to get to the mailbox first so my wife doesn't see my bank statement. smile.gif

    I'll have to make due with one for now.

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    I wonder if this wire is hot...
  • SN96SN96 Posts: 318
    edited 2005-10-03 18:27
    LOL! you don't need two irons. I had two at my work area that I use to add and remove parts (much faster!). I have one on my left hand and one in my right hand and I would go to town like a mad man with smoking chop sticks.

    I here ya about the bank statement. Here some more advice.... Burn the paper trail!

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    Mike

    --
    Formally RoboROOKIE.
    ·
  • BeanBean Posts: 8,129
    edited 2005-10-04 13:48
    I didn't see anyone answer about what to use to tin the board.
    I use "Liquid Tin" (JDR sells it).
    No heating or anything, just immerse the board and it will tin it almost immediately.
    Bean.

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    "SX-Video·Module" Now available from Parallax for only $28.95

    http://www.parallax.com/detail.asp?product_id=30012
    Product web site: www.sxvm.com
    Available now... SX-Video OSD module $59.95 www.sxvm.com

    "I'm a man, but I can change, if I have to, I guess"
    Red Green
    ·
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2005-10-05 00:39
    HI EVERYONE

    I can understand this very well and it kind-a funny

    "I've been spending so much on toys lately that"

    I do not have to worry about that i have own my bank account

    .....................Now to me this is funny.......................................................

    " I have to get to the mailbox first so my wife doesn't see my bank statement"

    "I here ya about the bank statement. Here some more advice.... Burn the paper trail!"

    ..................................................................................................................
    See my problem is that i still what to play like a kid
    ·when it come to my hobbies

    I do not want to grow up i still want to play·and spend all weeken do it and this get me·in·trouble( now i do not mean every weeken)· if you what i mean

    WHAT I have worry about is when the Wife comes and says loan me some money

    and i say i do not any money i bought my play toys like BS2 and the like

    She says have you spent enough money on your play toys

    Not yet


    SAM

    Post Edited (sam_sam_sam) : 10/5/2005 12:53:18 AM GMT
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