Hey guys, I haven’t use SMD component yet. Currently, I started my design with DIP Components. So, I am not having enough knowledge about SMD Packages but as per instructions from my guide, they suggest me to use SMD Packages. But still one doubt in my mind why to prefer packages instead of others. Can someone clarify my doubt??
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is the smallest SMT resistor that is still easy to solder.
is also still quite doable for most people, but it’s getting a bit smallish, and therefore more difficult.
and smaller gets hard without very good equipment such as stereo microscopes. (10x magnification is enough)
The bigger packages such as are also easy to solder, and sometimes have the advantage that you can route 2 unrelated tracks under them. Sometimes these bigger packages are needed because of power dissipation, for example with low value shunt resistors.
also has the benefit that it fits quite well on vero board, or on anything with a “standard” 100mil distance. is hard to fit on vero board because it’s too small.
A good way to start is to buy a “SMD sample book” from Ebay / Ali / China. You can get books with complete E12 range, and 50 or 100 pieces of cut tape in each size you want for around EUR25.
You can also buy these books with an transistor or diode assortment. Each shop has different transistors in them, so search for the datasheets to get an idea of the spread of the components.
Then there is technique and tools.
For hand soldering I prefer to first put a dab of solder on all the right pads, then exchange solder for tweezers in my left hand, place all components and solder them with the solder already on the PCB, and then solder the left side. Good tweezers are mandatory. With bad quality tweezers you can not pick up components reliably.
MikesElectricStuff has a nice overview with tips for SMT soldering, but there are also many other tutorials on youtube.
is my go to if other people may have to assemble them, I’m personally very comfortable with , passable on ’s and mainly struggle with ’s,
Key points are keep the spacing to the default courtyards at minimum, and increase based on how well you can handle precision,
I use gel flux to cheat quite a lot, pre tin the pads, put a small dot of gel flux on the package locations, put the part in place, the flux mostly keeps it held in place, then heat with low airflow with the hot air gun and in most cases it will self align onto the pads, occasionally needing a nudge to get the second pad to stick,
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I would say for a beginner, work off at least a 2mm gap between fab layer outlines on SMD components, I work off a 1mm, and its just on the edge where sometimes long rows of components will be a little annoying to separate from there neighbor. If your really not confident that 3mm,
I have had unsteady hands all of my life; mild “essential tremor”. I am 68. When SMT was introduced, I was intimidated by it. But nowadays I can hand solder chips routinely. One recommendation is that I like to use a relatively small footprint for my chips.This provides more room on the pad for the soldering iron tip.
’s? No. I have done them, but half the time I lose the chip in the drop of solder on the end of the soldering iron.
In my opinion, SMT is often easier than thru hole because you do not need to worry about holes filling with solder. I think it is much easier to change values of an chip on the board than to change values of a 0.25W thru hole resistor. So dive into it with courage. I do recommend a desolder tweezer. Two soldering irons can also work to heat both pads at the same time.
In my lab I stock and resistors but not s, with a few exceptions for milliohm values. If you have a small footprint, it might be easier to solder an chip onto those pads than an .
That usually requires a paste stencil, too. I have experience only with steel stencils, but I know it can be frustrating to learn to use it. can be soldered with an iron and the stencil isn’t needed. may barely be possible with an iron, too, but only with a good microscope (and good component placement as you said), and I don’t recommend it. Additionally it may be surprising that going to from saves relatively little space. With those sizes the tracks and especially vias take quite much of the space in the board and is worth it only if you can go for really thin tracks and smaller than standard vias – and actually really need all the space you can get.
As for the original question – why not just go after their recommendation. I think the opinions in this thread confirm that suggestion. The question of vs. is interesting in its own right, but not relevant for that.
I used to use for it one 110W trafo soldering iron and one soldering iron with sharp tip. When I have the element (typically ) taken out of PCB and between then I switch off the trafo soldering iron and the element stays at it and it is cold at once. Then I take tweezers to my second hand and take the element off the iron (by switching it on for a second).
In past (when I didn’t had those iron with sharp tip) I have also done special shaped wires used with trafo iron to heat both ends of elements like (I had also special shapes (with one leg bigger) for SOT23 and SOT323).
We switched from TH elements to and than to and then to and we finished that process in previous century. Now we use mainly and some (mainly 100n blocking capaciotors to place them close to IC pin pairs (VCC+GND) and to not block tracks from next pads.
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