Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [surface-mount]

Surface-Mount Technology (SMT) refers to the way components are mounted on a PCB: SMDs (Surface-Mounted Devices) have pins or contacts which lay on top of the PCB's pads, without the need for holes in the PCB.

SMT in PCB production became widely used in the late '80s.

SMT advantages:

  • Space-saving: since the components don't need mounting holes, both sides of the PCB can be maximally used.

  • Miniaturization: saves space. Components can be as small as 0.4 mm (01005 resistors) or 5 mm2 16-pin ICs, e.g. the LPC1102UK:
    enter image description here

  • Cost-saving: smaller components use less materials, and SMT needs less holes to be drilled in the PCB.

  • Less inductance: shorter connections have less inductance than PTH components, which increases maximum frequency.

Wikipedia: Surface-mount technology

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

How do I identify the markings on an SMT component and match it up with a part number so I can be a good designer and actually look at a datasheet (and read the whole thing)? Or identify a part to replace an unknown part on a PCB?
Voltage Spike
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What tools, equipment, and techniques do you use to solder fine-pitch SMT parts?

Possibly many questions have been asked on soldering smd parts, but I haven't found specific answers, Like: Do you use a watchmakers lens or some other type of magnifying glass while soldering these miniature components? What would be most optimum…
Kevin Boyd
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Vias directly on SMD pads?

I was looking at an example board schematic provided by TI and I noticed something rather curious: vias were placed directly on SMD pads. Is this a normal/acceptable practice to follow, or is it recommended/better to put a short trace and then have…
helloworld922
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How to hold SMD parts in place while soldering?

I go through this every time I have PCBs I need to populate with SMD parts, and this has become more an issue as pin spacings have gotten tighter, and my hands have become less steady with age. So far I've modified some curved tweezers with a…
Randy
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Why are SMD LEDs shipped in a sealed bag containing desiccant?

I had a selection of 0805 LEDs in my last Mouser order and was a bit surprised to discover they arrived in heat-sealed (rather than folded and taped with sticker) bags containing a desiccant bag and some sort of litmus-esque paper indicator saying…
scanny
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Safe temperature for desoldering SMD components w/ hot-air rework gun?

What is a reasonably safe temperature to use for desoldering SMD components using a hot-air rework gun? I have a new-to-me rework station from Xytronic and the documentation clearly assumes you know what you're doing… It tells you what temperature…
Kaelin Colclasure
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SMD soldering: tiny components stick to tweezer point

When soldering SMD components, the 2-pinned ones (like resistors, capacitors, ...) are the hardest in my opinion. I started long time ago with the 1206 format. Then scaled down to 0804, 0603 and finally I'm working with the 0402 ones. I'm facing a…
K.Mulier
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Should I worry about the risk of tombstoning?

A colleague has (apparently unsuccessfully :-)) tried to convince me of the risk of tombstoning in the following situation: He claims pad 1 for R55 and R59 will lose heat faster during soldering because they have two traces leaving, while pad…
stevenvh
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Is there a difference between SOIC and SOP?

I'm looking at two integrated circuit packages: SOIC and SOP. They seem (almost) identical (pitch, overall size, etc...) SOP SOIC Is there any important differences between these two packages that I am overlooking?
Ryan Jensen
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Why are there no BGA chips with triangular tessellation of circular pads (a "hexagonal grid")?

Ball grid arrays are advantageous integrated circuit packages when a high interconnect density and/or low parasitic inductance is paramount. However, they all use a rectangular grid. A triangular tiling would allow π⁄√12 or 90.69% of the footprint…
jms
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How do I prevent bridges while soldering SMD Components?

I have noticed that whenever I try to solder a component with many pins close together (like an IC), I get tiny bridges of solder, which shorts the pins. Is there any easy way to solder SMDs without solder bridges?
MetricSystemAdvocate
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Pre-programming surface mount ICs

I'm trying to set up a PCB with an atmega168 and no programming header. I intend to use a serial bootloader (there is a ft232 on the board) to reprogram but I am wondering about the best way to program the bootloader on. Has anyone else tried this…
jeremy
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Can you stack SMD resistors in parallel to reduce power dissipation per resistor?

I sent my PCB a couple of days ago for fabrication but just realized a terrible error: I need to send 70mA to an IR LED with a 5V supply so I would need a resistor of about 70ohm, which means the resistor would be dissipating 350mW of power. The…
Shubham
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Sizing SMD components for Hobbyist Kits

More components are only available in SMD packages. For hobbyist assembly the options are to buy breakout boards or solder SMD. Since components are usually packaged in a couple of SMD package types I am trying to put together a set of…
jluciani
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Difference between thin film and thick film precision surface mount resistors

I'm using some 0.1% precision 10k and 150k resistors. They are thin film 0603 surface mount. For a lot more, there are also thick film types. Fundamentally and practically, what is the difference between these two? Thin film example Thick film…
Thomas O
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