Author Topic: Come in through-hole components your time is up!  (Read 14393 times)

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Offline PlainName

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Re: Come in through-hole components your time is up!
« Reply #50 on: December 30, 2021, 09:50:30 pm »
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It's intuitive.

Is it? The DIL device scores by being able to have its legs bent over and soldered down on the other side of the board. That isn't going to come loose too easily. OTOH the SMD device is held on solely by the strength of the glue holding down the tiny pad. Levered with a screwdriver, as a test, I know which will come off first :)
 

Offline Cerebus

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Re: Come in through-hole components your time is up!
« Reply #51 on: December 30, 2021, 10:19:29 pm »
Quote
It's intuitive.

Is it? The DIL device scores by being able to have its legs bent over and soldered down on the other side of the board. That isn't going to come loose too easily. OTOH the SMD device is held on solely by the strength of the glue holding down the tiny pad. Levered with a screwdriver, as a test, I know which will come off first :)

You might use glue, the rest of us use solder. This may also be a clue as to why you've been having difficulty getting SMD stuff to work.  :)

But seriously, brazing/soldering about 50% of the area of a very light part (~10mg for a DHVQFN16)  to a board, as compared to suspending a heavier part (DIL16 1100mg) off the board on flexible metal legs it is intuitive which will be stronger, unless one has no mechanical intuition. Similarly the service loads on parts are a result of their mass being accelerated and decelerated, not some gorilla deliberately attacking them with a screwdriver.
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Offline PlainName

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Re: Come in through-hole components your time is up!
« Reply #52 on: December 30, 2021, 10:28:19 pm »
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You might use glue, the rest of us use solder.

Ah, a bit too quick on the clever reply so you missed:

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the strength of the glue holding down the tiny pad

Don't care how strong your soldered joint is if the pad lifts. This is why even SMD connectors often have either relatively huge mounting pads or hole for pins to be stick into.
 

Offline tautech

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Re: Come in through-hole components your time is up!
« Reply #53 on: December 30, 2021, 11:50:39 pm »
Quote
You might use glue, the rest of us use solder.

Ah, a bit too quick on the clever reply so you missed:

Quote
the strength of the glue holding down the tiny pad

Don't care how strong your soldered joint is if the pad lifts. This is why even SMD connectors often have either relatively huge mounting pads or hole for pins to be stick into.
Consider those might also be for shifting heat.  ;)

Otherwise I'm with Cerebus, less mass in a high vibration environment has to be better provided the PCB is also restrained properly.
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Offline Cerebus

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Re: Come in through-hole components your time is up!
« Reply #54 on: December 30, 2021, 11:51:11 pm »
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You might use glue, the rest of us use solder.

Ah, a bit too quick on the clever reply so you missed:

Quote
the strength of the glue holding down the tiny pad

Don't care how strong your soldered joint is if the pad lifts. This is why even SMD connectors often have either relatively huge mounting pads or hole for pins to be stick into.

Any arguments about the bonding of the foil to the substrate apply equally well to a through hole part but frankly that's irrelevant; all the mechanically failed through hole parts I've seen it's the actual leads that have broken, not pads. Both SMD and THT parts have adequate mechanical connection to keep them attached to the board except under extreme circumstances or deliberate attack. What the THT parts have that the SMD don't is a vibration failure mode that is much more important than whether the part can be ripped from the board or not. As I say, all the real life mechanical failures that I've seen have have been from that mode.

Arguing about connectors when we were talking about chip parts is just doing a bait and switch. Connectors are always going to require relatively heavy mechanical connections to boards if they're board mounted, whether they are SMD or THT. The 34 way through hole connectors I've got on order have bolt holes on them for a reason, 3M aren't expecting the solder pins to provide an adequate mechanical connection on their own.
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Offline PlainName

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Re: Come in through-hole components your time is up!
« Reply #55 on: December 31, 2021, 12:07:07 am »
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Any arguments about the bonding of the foil to the substrate apply equally well to a through hole part

Really? It's as easy to pull a bent and soldered leg back through a hole as it is to peel off a pad?

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but frankly that's irrelevant

Though that didn't stop you throwing in that little bon mot. Either it's irrelevant or it's worth making a point, can't have both.
 

Offline Cerebus

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Re: Come in through-hole components your time is up!
« Reply #56 on: December 31, 2021, 12:22:20 am »
Quote
Any arguments about the bonding of the foil to the substrate apply equally well to a through hole part

Really? It's as easy to pull a bent and soldered leg back through a hole as it is to peel off a pad?

Quote
but frankly that's irrelevant

Though that didn't stop you throwing in that little bon mot. Either it's irrelevant or it's worth making a point, can't have both.

You were the one who brought up bonding strength. If I don't answer you point about it you'll say I'm glossing over it, if I do answer it you act as if I brought it up as a fallacious argument. Make your mind up, either is it important, or it's a red herring; you seem to want it both ways depending on whether it bolsters your point of view or not.
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Offline Ground_Loop

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Re: Come in through-hole components your time is up!
« Reply #57 on: December 31, 2021, 02:17:49 am »
There was a time when I absolutely hated surface mount. But after kitting myself out and practicing a bit I now prefer surface mount. Look closely at attached perfboard bottom side pic. They make assembly so much cleaner.
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Offline PixieDust

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Re: Come in through-hole components your time is up!
« Reply #58 on: December 31, 2021, 02:50:35 am »
all the mechanically failed through hole parts I've seen it's the actual leads that have broken, not pads.

Wow really? Interesting. I presume the failed components were dual lead? I can't imagine a single lead on an IC breaking, but I guess a single lead of a diode for example, well I can see that happening.
 

Offline Cerebus

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Re: Come in through-hole components your time is up!
« Reply #59 on: December 31, 2021, 03:57:57 am »
all the mechanically failed through hole parts I've seen it's the actual leads that have broken, not pads.

Wow really? Interesting. I presume the failed components were dual lead? I can't imagine a single lead on an IC breaking, but I guess a single lead of a diode for example, well I can see that happening.

Yeah the things with more leads tend to fair better. It's usually poorly supported TO-220s and their ilk  that are the first things to go, then radial electrolytic caps, and only then small resistors, diodes and the like. There's pretty much a direct relationship between the ratio of device mass to total lead area cross-sectional area and the probability of failure. I've only seen these in things designed for relatively light duty applications (or carelessly designed), things intended for harsh environments tend to get the extra attention to ruggedness that they deserve.

The classic culprits? Audio gear designed for domestic use pressed into semi-professional use on the road. Falls apart in no time at all.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
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Offline PixieDust

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Re: Come in through-hole components your time is up!
« Reply #60 on: December 31, 2021, 07:17:18 am »
Makes sense.
 

Offline bsfeechannel

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Re: Come in through-hole components your time is up!
« Reply #61 on: January 02, 2022, 03:20:20 am »
Through-hole will never die.

 


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