76 votes
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How do I identify SMD components? (or how do I identify any component)

Step 1) Identify the package, note how many pins, match up the pins first. Note that sometimes the package pins are underneath the part or extended away from the part. Also get the dimensions of the ...
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  • 63.7k
49 votes
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Why are SMD LEDs shipped in a sealed bag containing desiccant?

Through-hole components are generally hand or wave soldered. These apply on local heating to the pads and not to the component itself. SMD parts on the other hand are generally reflow soldered. This ...
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31 votes
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How do I prevent bridges while soldering SMD Components?

When soldering by hand, it is easier and faster to just ignore the bridges while you solder the part and then clean it up. Just put some desoldering wick on the bridge, heat with your soldering iron ...
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30 votes
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Hand soldering SMD 1206 components

You will likely find that 1206 are actually quite easy to hand solder. When you get used to SMD boards, you will find they are actually quite large. With a standard iron, I find it quite simple to ...
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  • 11.5k
26 votes
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Ways to get SMD resistors from a strip

You should try vacuum tweezers. They are a bit varied, there are some super cheap ones and others more sophisticated: Cheapest option, which I dont recommend. When you press or release the vacuum ...
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  • 7,610
26 votes
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Help me identify this resistor

It's a current shunt - 68 milliohms. That's what the "M" stands for. It's used to measure the current drawn by the circuit which also explains its large size (and therefore high power rating)...
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  • 7,218
26 votes

Is this a zero ohm resistor?

That cuticle shape of the pads is characteristic of ferrite beads, for some reason. As is the black sides of the part. Resistors typically expose the alumina substrate on the sides: It's hard to ...
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25 votes

How to hold SMD parts in place while soldering?

Pssshh to the guys using stencils :) Bet I can put a QFP down faster than you can paste, place, and re-flow :) Although it's nice if you want to get that center pad soldered. Seriously though if we'...
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25 votes
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Why are there no BGA chips with triangular tessellation of circular pads (a "hexagonal grid")?

Unless you use via-in-pad, which costs more, you need room to put routing vias in between the pads, like this
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  • 6,048
24 votes
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How to hold SMD parts in place while soldering?

I just saw the SMD beak on Hack-a-day that looks like what you are looking for (I want one!)... http://vpapanik.blogspot.de/2015/02/the-smd-beak.html I've also had luck... use a little piece of ...
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  • 9,410
24 votes

SMD 0402 resistor flipped on its side

It's called "billboarding". The IPC standard is mute on the precise reason, but it notes that billboarding may occur during assembly. That condition is acceptable for all three IPC classes ...
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  • 7,210
23 votes
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Does Intel sell CPUs in ribbons?

yes 14.6 Handling: Shipping Media 14.6.1 Mid-temperature Thin Matrix Tray The BGA packages are shipped in either a tape and reel or a mid-temperature thin matrix tray that complies to the JEDEC ...
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23 votes

Keeping SMD parts in place while soldering with paste and heat

they suggested was that I use a stencil to apply my paste more evenly. In other words, they blew off my question. No, they didn't. They gave you correct advice. If you have a lot of solder on one ...
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23 votes

Thin wall to block LED light from hitting photodiode?

My advice is to not bother doing what you're doing, and spend the $3.50US to get the part designed for the task, like https://www.digikey.com/product-detail/en/osram-opto-semiconductors-inc/SFH-7060/...
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23 votes

SMD ceramic capacitor 0805 vs 1206

The short answer, for your circuit, it won't matter. When it comes to ceramics, there is a dirty little secret. When you apply a DC voltage to them, their capacitance values go down. Sometimes very ...
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  • 6,032
21 votes
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Is it safe to repeat reflow soldering?

There is no generic answer, it all depends on the components involved, let me add a few things to watch out for, and collect for the convenience a few more from the comments. First of all, read the ...
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  • 6,319
21 votes
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Which is better - components on both sides or components on one side of the PCB?

PCB size is not the only cost consideration and you need to consider recurring costs vs. one time (non-recurring) costs (some of the non-recurring may actually occur more than once for a 50k run). ...
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  • 21.5k
21 votes
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Why do some SMD electrolytic capacitors have platforms?

Those capacitors are really made similarly to the cylindrical radial lead through-hole capacitors. Two connections come out through a rubber bung (in an aluminum case that is crimped at the bottom to ...
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20 votes
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Should SMD footprints be rounded?

Yes, SMD footprints should have rounded corners as per IPC-7351A Corner radius is 25% of the shorter side of the pad but not more than 0.25mm (10mil which is not exactly the same but close enough ...
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  • 1,581
20 votes

Using a home oven for solder paste

Lots of people use toaster ovens and electric fry pans for reflow. It can get a little touch and go with lead-free solder, and I recommend leaded solder. Large kitchen ovens likely don't have the ...
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20 votes
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How to solder an SMD component with a "pad" on the bottom?

The absolute best way to do this is to preheat everything with a large high flow hot air source or oven. Apply paste first, if you have it, or a little bit of wire solder to the pad. Then pre-heat. ...
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  • 24.4k
20 votes
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Anyone either read japanese or know about laying tracks for a micro SD card slot?

Google translate on your phone can do this: Parts prohibited area (部品搭軾禁止エリア) Pattern prohibited area (パターン禁止エリア) Soldering prohibited area (半田付け禁止エリア)
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  • 20.8k
20 votes
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Identify unknown SMD component code A6530 72130

"F1" indicates some kind of fuse, and that "B" is the Bourns logo. Googling "Bourns A6530" leads to the TBU-CA datasheet, which says: The TBU-CA Series of Bourns® TBU® products are low ...
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  • 14.6k
20 votes
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Need to keep re-soldering SMD resistors on PCB

This seems to be plumbing flux, which often is higher in corrosive components than electronics fluxes. Considering solder wire comes with a rosin core, you'll probably be better off without that flux, ...
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19 votes
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Solder paste not wetting at all

My guess would be that the copper board is not being given enough time to heat up. Due to its thermal mass the copper heats up much more slowly than the solder, and the solder melts before the board ...
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  • 20.3k
19 votes

Anyone either read japanese or know about laying tracks for a micro SD card slot?

Disclaimer: I am clueless about EE, but read Japanese well enough to look this up. Black box: 部品搭載禁止エリア = "components/parts-loading prohibited area" (don't put stuff here, I assume). Diagonal ...
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  • 291
19 votes
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How can the ACS712 pin handle 20 A?

Do note that this IC has been discontinued and not recommended for new designs, they recommend the ACS723 instead. It also comes on a 30A version on the exact same package. PCB trace calculators rely ...
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  • 8,165
19 votes

What is this SMD component, marked as D7 with an underline?

That looks like an LP-USML400 resettable "polyfuse" made by Way-On. Datasheet here
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  • 13.3k
19 votes

Need to keep re-soldering SMD resistors on PCB

As others have pointed out, your issue will be one of using the wrong type of flux. Plumbing flux is highly corrosive and will damage your board and components. It should not be used for soldering. ...
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