EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: bjdhjy888 on September 25, 2019, 12:43:06 am
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:'(
When I just started to learn electronics, I loved using through hole parts, like 555 timer, resistors, and hated SMD parts, as the former is so easy to be used on a breadboard.
As soon as I learned Altium, I felt I never wanted to used ANY through hole parts. They are too big, ugly and not cool when it comes to aesthetics. I hardly use non-SMD parts. My PCB is soldered with footprints of 0805, LQFP, SOT223, QFN, etc.
But I see lots of advanced engineers who do use through hole parts, which kinda ran the bell for me.
Am I being wrong or too obsessed with SMD/SMT?
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I find it much easier, faster, and less tedious to assemble a board with all SMD parts. I don't miss thorough-hole at all.
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TH has an warm nostalgic value to me. But i also do only SMD now.
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I try to get everything I can as through hole and 2.54 pitch so that it fits on breadboard and protoboard. I'm still new and experimenting so no high volume stuff. Once I get to a point where I want to do more volume then I would convert stuff over to using SMD and just design and get boards manufactured. I've tried to solder SMD without having a PCB and it's just so tedious, not worth the hassle.
I do have some oddball parts I want to play with that only came in SMD but I was unable to solder them at all, they are just too small even to just add leads to, too hard to make them not move around etc while trying to solder. So at some point I'll get some break out boards made. SMD is not too hard when you have a proper board with solder mask etc but trying to experiment and prototype them is tedious.
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I find it much easier, faster, and less tedious to assemble a board with all SMD parts. I don't miss thorough-hole at all.
^ This
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The only time I use TH parts is for when I need the mechanical stability. Everything else is SMD.
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I use SMD whenever possible, but sometimes through-hole makes sense. Mechanical factors, or because I already have a bag of them. I also typically use through hole when I want to prototype something without a PCB.
Doesn't really matter one way or the other.
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Am I being wrong or too obsessed with SMD/SMT?
Yep.
While great unless great care is taken it's easy to mix cap values as they're unmarked.
Then you have to outlay for SMD tweezers however once you have you'll never regret the cost.
If doing SS PCB's in SMD it's sometimes difficult to route them while just the addition of a TH passive or 2 can open up paths for routing that otherwise might be hard to find. Sure you could use a jumper or even a big zero ohm SMD to do the same thing but it's another item to the BOM whereas using a TH resistor on hand kills 2 birds with one stone. ;)
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I'm using a pair of stainless tweezers I think I paid $3 for on ebay, they work fine for placing SMD components.
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Expounding on why I prefer SMD to through-hole:
To build a board with through-hole components:
- Pick up part
- Bend (or straighten) leads to fit through holes
- Insert part through holes
- Repeat for all parts
- Turn board over (hoping nothing falls out)
- Solder leads one at a time
- Clip excess leads (and hope you don't get one in your eye :o)
- Optional: find all of the stray clipped leads that went flying
To build a board with SMD components:
- Tape stencil to board
- Apply solder paste and squeegee it across board
- Remove stencil
- Pick up parts with tweezers
- Place on board
- Repeat for all parts
- Put board in oven and reflow
I find the SMD procedure to be both less tedious and faster to do. The through-hole process assumes you don't have a wave soldering machine, which most hobbyists don't.
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stencil？
:horse:
:scared:
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stencil？
:horse:
:scared:
Laugh it up fuzzball, but stencils save me loads of time.
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stencil？
:horse:
:scared:
Laugh it up fuzzball, but stencils save me loads of time.
Never bothered with them for prototypes or 'one off's'.
We each have or tricks for one off SMD work like tinning pads first, hold parts in place and reflow the pad with an iron then solder the other end and then finish the first pad.....done at least 4 in the time it took me to type this.
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The video in this post is a worthwhile watch and there's also some good SMD ideas throughout this thread:
https://www.eevblog.com/forum/beginners/so-surface-mount-it-is/msg1442590/#msg1442590 (https://www.eevblog.com/forum/beginners/so-surface-mount-it-is/msg1442590/#msg1442590)
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The video in this post is a worthwhile watch and there's also some good SMD ideas throughout this thread:
https://www.eevblog.com/forum/beginners/so-surface-mount-it-is/msg1442590/#msg1442590 (https://www.eevblog.com/forum/beginners/so-surface-mount-it-is/msg1442590/#msg1442590)
Surface tension pulled the soder pasted onto the leads?
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The video in this post is a worthwhile watch and there's also some good SMD ideas throughout this thread:
https://www.eevblog.com/forum/beginners/so-surface-mount-it-is/msg1442590/#msg1442590 (https://www.eevblog.com/forum/beginners/so-surface-mount-it-is/msg1442590/#msg1442590)
Surface tension pulled the soder pasted onto the leads?
Yep and adequate flux is your friend for this. ;)
As an aside I've never been tempted to change my profile avatar such is my hate of that PB free muck they use these days.
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No question, SMD is better in almost every situation. But hate is the wrong response. Because that will lead to picking the wrong answer sometimes. Just recognize that for what you are doing SMD is a better answer and keep doing it. If you do something different and it seems to be coming hard it is worth spending a few moments to see if you need to look elsewhere and this is where a hate response can leave you struggling unnecessarily.
One example: High power dissipation. 100W SMD resistors don't exist AFAIK, and an array of 200 half watt SMD spaced so they can dissipate power independently isn't a always a pretty answer.
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(https://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Intel_C8086.jpg/220px-Intel_C8086.jpg)
:P
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Expounding on why I prefer SMD to through-hole:
To build a board with through-hole components:
- Pick up part
- Bend (or straighten) leads to fit through holes
- Insert part through holes
- Repeat for all parts
- Turn board over (hoping nothing falls out)
- Solder leads one at a time
- Clip excess leads (and hope you don't get one in your eye :o)
- Optional: find all of the stray clipped leads that went flying
To build a board with SMD components:
- Tape stencil to board
- Apply solder paste and squeegee it across board
- Remove stencil
- Pick up parts with tweezers
- Place on board
- Repeat for all parts
- Put board in oven and reflow
I find the SMD procedure to be both less tedious and faster to do. The through-hole process assumes you don't have a wave soldering machine, which most hobbyists don't.
All that only really applies if you have a PCB made though, ex: higher volume. Would not bother getting a PCB made for a one of project. Doing SMD with bread boards or perfboards is not very fun. Doable, but through hole is easier.
I mostly work with through hole myself but once I decide I want to get a PCB made for a project that I want many of then I'll probably convert a lot of stuff to SMD.
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All that only really applies if you have a PCB made though, ex: higher volume. Would not bother getting a PCB made for a one of project.
Getting a PCB made these days is so cheap I do it for every project, even one-offs (which the vast majority of my projects are).
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Just to throw in my two cents... I think that through hole components (most of them) have reached the "back-to-the-old-times project" type. Where if you want to build something vintage, you use through hole components.
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I don't miss TH whatsoever. (If I miss it sometimes, it's just for nostalgia for this period, but not for anything technical.)
My only gripe is with SMD connectors. Many are too fragile for my taste compared to their TH counterparts.
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All that only really applies if you have a PCB made though, ex: higher volume. Would not bother getting a PCB made for a one of project. Doing SMD with bread boards or perfboards is not very fun. Doable, but through hole is easier.
I mostly work with through hole myself but once I decide I want to get a PCB made for a project that I want many of then I'll probably convert a lot of stuff to SMD.
I prefer SMD for self-etched PCBs because I don't have to drill all those damn holes. I rarely etch my own boards anymore but I still do now and then when I only need one of something and I want it now.
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All that only really applies if you have a PCB made though, ex: higher volume. Would not bother getting a PCB made for a one of project. Doing SMD with bread boards or perfboards is not very fun. Doable, but through hole is easier.
I mostly work with through hole myself but once I decide I want to get a PCB made for a project that I want many of then I'll probably convert a lot of stuff to SMD.
I prefer SMD for self-etched PCBs because I don't have to drill all those damn holes.
Holes are not at all hard to drill with just a Dremel press and HSS bits in phenolic PCB material.
Go to FR4 and drilling is harder.
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Holes are not at all hard to drill with just a Dremel press and HSS bits in phenolic PCB material.
Go to FR4 and drilling is harder.
They're not hard to drill, I have a self made precision drill press with carbide bits but it's still tedious to drill several hundred holes.
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Holes are not at all hard to drill with just a Dremel press and HSS bits in phenolic PCB material.
Go to FR4 and drilling is harder.
They're not hard to drill, I have a self made precision drill press with carbide bits but it's still tedious to drill several hundred holes.
A little trick is to make the hole in the annular ring quite small and it helps immensely to center the bit and so speeds up the job. This works well with HSS bits and Phenolic PCB's but go to tungsten bits and they don't have the same flexibility.
SMD PCB or not, there are still holes to be drilled.
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Yeah I do that and it does help, I got quite proficient at it for a while. I should post a picture of my drill press, I hacked it together out of some scraps of 2x4 lumber with a precision slide I had laying around, intending it to be temporary but that was 10 years ago. It worked so well I just kept using it.
Now it's so insanely cheap to get PCBs that I rarely etch my own but it's still fun now and then and as I mentioned, when I want something today I can go from idea in my head to a board in my hand in a couple of hours and I can do it while I watch a movie or something in the background.
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Well, I prefer SMT components too, they're faster to mount onto a PCB and overall performance is better, at least that's how I feel about it, but I must admit that there are a couple of situations when you're going to want to go with THT over SMT.
If you're designing a device you know will be under a lot of stress, you might be better off using THT as it provides stronger bonds.
THT is good for fast prototyping
For connectors, THT is recommended, you really want those to stay in place, some designers might even go for screws to hold those connectors in place, as seen here https://titoma.com/blog/smt-smd-bga-tht-meaning (https://titoma.com/blog/smt-smd-bga-tht-meaning)
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Not only, but I have a tendency to make an SMD board as flat as possible. To the extend, where I dont use SMA diode, because DO123FL is has less height. Or a DFN instead of SO8 package.
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Gotten far too used to having a 50x50mm PCB filling up almost a meter of screen area, so yes through hole parts are left looking comically oversized, until you need to solder them :)
In reality I am usually stuck using through hole as the people who will be servicing the things want it as easy as possible to handle field replacements. (300 deployed, 1 failed due to vehicle being trapped in flood waters after 2 years.. don't know what they think they will need to service)
Even gotten to the point of curving traces and using odd chip rotation angles on compact layouts just to squeeze things closer for personal projects, its surprising how dense you can make things if you don't stop to take a big picture look from time to time. e.g. wireless data loggers with a year worth of memory, where the CR1632 coin cell was what determined the size of the PCB, everything else was sitting comfortably.
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Another important difference: SMDs perform better.
There is unfortunately a dearth of heatsinkable parts in SMT, making it difficult to do anything that handles much power.
This alone does prioritize switching supplies quite a bit: if you can't afford to dissipate even a whole watt in say a SOT-89 linear regulator, you're forced to use a switching converter, and you'll just have to suffer the improved efficiency... ;D
When you do need to handle power, you don't have much choice but to stick with THT parts, TO-220s and such (and power resistors in various packages). These all have long, spindly legs: in a high efficiency switching converter, or a wideband amplifier, the lead inductances of ~10nH are very significant. This puts an upper limit on switching speed and losses.
Whereas D2PAKs have maybe 3-5nH inductance, and DFNs can have almost nothing.
There are somewhat more options these days, from DirectFETs, to exposed-die or thermal-plate DFNs, to CSPs and bare dies; and with device performance continuing to improve, achievable efficiency continues to rise.
Tim
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yeah, heat dissipation is an issue, and I wonder why smd components are so unfriendly to heatsinks. I've seen parts with, say, a thermal pad on top, but that's an exception, most datasheets just say "have enough board area and solid planes to soak the heat". There are a few heatsinks that can be soldered to the board, but they are only good for a watt or two. So, for my power supply I'm going to use to-264, even though it's going to be laying on the board (just like to-252, but thermal pad upwards so I can screw to a heatsink).
BTW, how do you prototype smd parts? For prototyping I still use breadboards. I use smd-to-th adapters quite frequently. I don't have any hate for TH, and I use quite a lot in prototypes. Making PCBs is fun, but I put my order (actually my first pcbs ever) on jlcpcb three weeks ago and it's still not delivered yet. May be if wasn't so greedy and order a DHL delivery it would be faster, but I'm worried they'd charge me with VAT and paperwork taxes.
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Another important difference: SMDs perform better.
There is unfortunately a dearth of heatsinkable parts in SMT, making it difficult to do anything that handles much power.
This alone does prioritize switching supplies quite a bit: if you can't afford to dissipate even a whole watt in say a SOT-89 linear regulator, you're forced to use a switching converter, and you'll just have to suffer the improved efficiency... ;D
When you do need to handle power, you don't have much choice but to stick with THT parts, TO-220s and such (and power resistors in various packages). These all have long, spindly legs: in a high efficiency switching converter, or a wideband amplifier, the lead inductances of ~10nH are very significant. This puts an upper limit on switching speed and losses.
Whereas D2PAKs have maybe 3-5nH inductance, and DFNs can have almost nothing.
There are somewhat more options these days, from DirectFETs, to exposed-die or thermal-plate DFNs, to CSPs and bare dies; and with device performance continuing to improve, achievable efficiency continues to rise.
Tim
Oh, yeah, dont even get me started on power dissipation. I have a constant need for high power Zeners. It is for fault conditons, that is supposed to protect other electronics components. So I have a need of 3-4W rated zener diodes, and there just isnt any. TVS would do, but they dont have DC specifications.
BTW, how do you prototype smd parts?
You design a board quickly and order it on 2 days service.
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Yeah, that's a good way to mount things, against the board. Can even use the board as a clamp, for more even pressure than the normal screw hole provides (just don't place SMT chips too close to the screws, because strained PCB).
I do SMTs this way,
(https://www.seventransistorlabs.com/Images/GD9.jpg)
Use a utility blade (to cut V-grooves) or rotary tool to slice up islands and traces on blank copper clad. Hit it with some sandpaper to remove burrs and clean the surface, then tin it, then place and solder components.
SOIC is easy to do this way, but TSSOP and such are not so easy. Ordering pre-baked or custom breakout boards is probably the better way. PCBs are easy to make and very cheap to order (if you don't mind a longer lead time due to current events).
And you can surface-mount THT components too. Those are easier done between Manhattan style pads, just cut off chunks of copper clad then solder them to the base.
Tim
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I'm pretty much the same.
The exceptions are for large capacitors (I hate SMD electrolytics with a passion and avoid them where possible because they are a right pain to hand solder) and for power electronic parts where it isn't possible to fit an SMD part for one reason or another (power dissipation, voltage standoff, etc.)
I quite like mixed SMD and through hole boards - e.g. plasma TV sustain boards.
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Expounding on why I prefer SMD to through-hole:
To build a board with through-hole components:
- Pick up part
- Bend (or straighten) leads to fit through holes
- Insert part through holes
- Repeat for all parts
- Turn board over (hoping nothing falls out)
- Solder leads one at a time
- Clip excess leads (and hope you don't get one in your eye :o)
- Optional: find all of the stray clipped leads that went flying
To build a board with SMD components:
- Tape stencil to board
- Apply solder paste and squeegee it across board
- Remove stencil
- Pick up parts with tweezers
- Place on board
- Repeat for all parts
- Put board in oven and reflow
I find the SMD procedure to be both less tedious and faster to do. The through-hole process assumes you don't have a wave soldering machine, which most hobbyists don't.
The problem i have with this is that sometimes you just want to quickly put something on a semi-permanent circuit board so you can get a prototyping stripboard (ex: https://www.aliexpress.com/item/32851976239.html (https://www.aliexpress.com/item/32851976239.html) ) and solder parts ... 0603 and 0805 and 1206 are doable but others not so much.
Also ... sometimes you don't get stencil with your circuit board esp. if there's multiple small designs you make and if you're not doing lots of boards the solder paste can dry out or become hard to use after some time, and it's recommended to be kept refrigerated so you have to be careful where it's stored in the fridge etc etc... so you have to mess around with adding isopropyl alcohol....
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BTW, how do you prototype smd parts?
You design a board quickly and order it on 2 days service.
That will break the bank :(. Btw, what services do you use for such a fast manufacturing and delivery?
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BTW, how do you prototype smd parts?
You design a board quickly and order it on 2 days service.
That will break the bank :(. Btw, what services do you use for such a fast manufacturing and delivery?
Yeah, I tend to think about this differently. Paying a 200 EUR extra is not that expensive, if you can avoid a day of downtime in engineering. Boards are typically Eurocircuits or Multi Circuit Boards.
Most of my prototypes are built for RF purposes, or temperature related questions (constant issue with ATEX). And for both of these you wanted to have the same layer stackup as the final boards, so breadboarding is out of question anyway. And while design problems typically occur, they are usually swapped digital lines or some other simple PECKAC and for that you need production prototypes.
If I need a prototype for home, then ordering from China is not a big deal. Maybe I have to wait 2-4 weeks to get it, but I dont have urgent projects anyway.
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The only time I use TH parts is for when I need the mechanical stability. Everything else is SMD.
Yup. Same here.
There's still a whole range of connectors for instance which I don't trust mechanically when they are 100% SMD, and favor those that have at least two anchor points that are TH, preferably three.
Back when I was still occasionally making my own PCBs, which were single-sided only (never bothered making double-sided PCBs, too much hassle), I used to mix SMDs and TH components to ease routing, as the SMD/TH mix would allow having parts on both sides with almost no need for straps - I'd call that 1 1/2 sided :-DD
With all the cheap and fast PCB services out there now, I don't bother anymore.
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Back when I was still occasionally making my own PCBs, which were single-sided only (never bothered making double-sided PCBs, too much hassle), I used to mix SMDs and TH components to ease routing, as the SMD/TH mix would allow having parts on both sides with almost no need for straps - I'd call that 1 1/2 sided :-DD
This is still practiced quite a lot in the industry. Look at power supplies, SMD one side, through hole the other side. SMD and through hole parts act as bridges as necessary, with jumper wires minimised if possible.
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Back when I was still occasionally making my own PCBs, which were single-sided only (never bothered making double-sided PCBs, too much hassle), I used to mix SMDs and TH components to ease routing, as the SMD/TH mix would allow having parts on both sides with almost no need for straps - I'd call that 1 1/2 sided :-DD
This is still practiced quite a lot in the industry. Look at power supplies, SMD one side, through hole the other side. SMD and through hole parts act as bridges as necessary, with jumper wires minimised if possible.
True :)
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Back when I was still occasionally making my own PCBs, which were single-sided only (never bothered making double-sided PCBs, too much hassle), I used to mix SMDs and TH components to ease routing, as the SMD/TH mix would allow having parts on both sides with almost no need for straps - I'd call that 1 1/2 sided :-DD
This is still practiced quite a lot in the industry. Look at power supplies, SMD one side, through hole the other side. SMD and through hole parts act as bridges as necessary, with jumper wires minimised if possible.
True :)
True again.
With the following needed comment:
- SMD **CAN NOT** be bended or twisted - it fails miserably
- SMD **CAN NOT** hold the stress of huge/large/heavy connectors
- SMD **CAN NOT** deform and vibrate (being PLANAR) as THT
- SMD tends to accumulate more power density than THT
Reason why PSUs are mostly THT and several connector
boards are *must be* THT (automotive and stress environs)
IMHO While being fancy smaller cute cheaper
PLANAR mounting tends to crack (MLCC and friends)
and are not as good as THT in power dissipation
Thing of: using the PCB as a HEAT SINK ?
Solutions are not that effective in SMD for high heat sinking problems
Where THT still is ahed?
= it deforms insanely more without cracking
= vibration is less an issue ( they are NOT COPLANAR - own resonance)
= THERMAL SOLUTIONS ARE FAR BETTER
= the boards can DEFORM/BEND and TWIST (including connectors)
= MUCH HIGH MECHANICAL STRESS.
Still a serious issue where it fits. - fancy stuff aside
Paul
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In addition to what other posters have mentioned, (thermal dissipation, connector ruggedness) the time I like to use TH components is when I am building a retro project.
When I do, as an aesthetic reason, I also like to orient resistors to have the tolerance band all facing the same direction.
But even then, there will be components which are only available as SMT. In those instances, I place them hidden on the board's bottom. ;)
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(..))
When I do, as an aesthetic reason, I also like to orient resistors to have the tolerance band all facing the same direction.
(..)
Another excellent reason.. SMD has become so tiny
soooooo tiny - they are mostly UNREADABLE
They have become a hazard solution when you need
to replace something without a single clue of specs.
That does not happen in THT - they are marked
and responsible codes can be taken seriously.
SMD in the present form represents a safe issue
for replacing non marked - even obscure tiny things
you can not even identify ...
Another very *VERY* don't underestimate that.. safety reason
where it fits
Paul
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The only time I use TH parts is for when I need the mechanical stability. Everything else is SMD.
^^^ This and power devices unavailable in SMT but I do some proto with THs.