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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.

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42
votes
8answers
5k views

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 ...
40
votes
9answers
15k views

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 ...
35
votes
1answer
58k views

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 ...
33
votes
2answers
3k views

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 ...
29
votes
3answers
8k views

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 ...
28
votes
6answers
4k views

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 ...
27
votes
7answers
28k views

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 ...
26
votes
5answers
96k views

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 ...
24
votes
4answers
3k views

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 ...
22
votes
8answers
3k views

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 ...
20
votes
8answers
7k views

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 ...
20
votes
9answers
3k views

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 ...
20
votes
4answers
5k views

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 ...
20
votes
2answers
19k views

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 ...
19
votes
2answers
7k views

Does Intel sell CPUs in ribbons?

I used to work at this electronics assembly plant in Arizona, and the machines there used reels of SMT parts that were like a bucketed plastic ribbon with a peel-off plastic seal. I don't know what ...
18
votes
4answers
2k views

Why are power supplies almost always made using through hole components?

Why are power supplies almost always made using through hole components? Every computer PSU I've taken apart uses through hole components, though occasionally (not in all cases) surface mount ...
18
votes
13answers
5k views

Recommended PCB houses / Assemblers [closed]

Can anyone recommend a good place to go making PCB's? I'm particularly interested in places that also offer assembly, because this makes SMD parts an option. GoldPhoenix is an option, but not the ...
17
votes
6answers
3k views

SMT solder reflow temperature profile

I have read many website and forums about DIY reflow ovens for SMT soldering. I have also seen many solder profiles as specified by the solder manufacturers, component manufacturers, and other self-...
16
votes
8answers
11k views

DIY SMT Reflow: Toaster Oven, Skillet or?

I've read quite a few write ups on converting toaster ovens or skillets for reflowing SMT components. The important parts appeared to be: Attempting to match a reflow profile (temperature pattern to ...
16
votes
4answers
2k views

What is the best way to short adjacent SMD pads?

Which of the three ways shown above would be the best way to short two adjacent SMD pads together, and why? These are TSSOP pads and the assembly process will be lead-free reflow, if that matters. ...
16
votes
2answers
2k views

Ways to get SMD resistors from a strip

I'm doing some SMD hand soldering occasionally and am looking for a better way of getting SMD resistors from a strip, so their orientation is upside up and their reading is e.g. from left to right. I ...
16
votes
2answers
14k views

The “right” 0805 footprint land pattern

My PCB design software comes with some libraries that include some common components, like chip resistors and capacitors. I have noticed, however, that the footprint land pattern for the 0805 ...
15
votes
10answers
8k views

How to solder an SMD component with a “pad” on the bottom?

I am getting a PCB manufactured for a project that I am working on. One of the parts, the A4950 motor driver (datasheet), has a "pad" on the bottom, which is meant to be soldered to GND of the PCB for ...
15
votes
5answers
2k views

SMD IC mounted upside-down inside a drill hole for extreme low-profile requirements

I don't know if the title is descriptive enough, but I came across this PCB and could stop to wonder about its brilliant design. It is an aftermarket trigger controller for an airsoft gun that works ...
15
votes
2answers
4k views

How can I use my SMD Arduino to program a separate DIP ATmega328?

I have an arduino with a surface mounted (SMD) microcontroller: I know how to use a DIP arduino as a programmer for a DIP ATmega328. It's easy --you just pop your microcontroller in the holder. ...
14
votes
4answers
2k views

How can I indicate pin 1 on a SMT package footprint without silkscreen

Sometimes when I order PCBs from a board house, I omit the bottom silkscreen for budgetary reasons. When I place surface-mount chips on the bottom of the board, I then end up with a footprint that ...
14
votes
5answers
6k views

PCB-less prototyping with surface mount components (like DFN)

I'm expecting some interesting comments and answers on this one, mainly because I'm probably just insane for even considering / asking this. One component I want to prototype with is the MCP73123 ...
14
votes
3answers
4k views

Is it safe to repeat reflow soldering?

I have a board that is partially reflow soldered with a QFN and a couple of 0603 capacitors and resistors. I wanted to test functionality with this stage before I go ahead and place the other ...
14
votes
1answer
1k views

Small SMD components: are they really capable of withstanding high voltages?

You can easy find some SMD components which are pretty small for such a high voltage (500V @ 0805 package for example - crazy?!). 0805 case would have 1.3 mm distance between the contacts, so I doubt ...
13
votes
3answers
9k views

How are SMD microcontrollers preloaded with code?

Often when you buy an SMD microcontroller (say AVR) or a PCB with an SMD microcontroller it comes preloaded with whatever program that board uses to run. I was wondering how it is preloaded - I guess ...
13
votes
1answer
3k views

Is there a good replacement for stripboard in the surface mount world?

More and more components I want to use are only available in surface mount packages. I can either get a big collection of adapter boards for all flavors of SOIC/WFBGA/QDERP to 100 mil pin spacing, ...
13
votes
1answer
3k views

What is a good methodology to identify small SMD components?

Having been in the position of trying to identify a strip of mystery 0603 components I found on my floor, I thought a good general question to pose to this community might be what a recommended set of ...
12
votes
7answers
2k views

How can the ACS712 pin handle 20 A?

I am searching for some current measuring ICs and found the ACS712, but what I can't figure out is how the seemingly small pins can handle the 20 A current since the trace width calculators say that I ...
12
votes
2answers
509 views

How to assemble PCBs when SMT machine doesn't have enough feeders?

I just got access to an SMT machine in a DIY fablab. I have a board that has about 50 unique components that I wish to assemble and test drive this new machine. I intend to make 20 of these boards. ...
12
votes
3answers
11k views

KiCad : How can I create a footprint with thermal vias?

I have a SMD chip that gets pretty warm when operating and I want to try and design a footprint that allows more ventilation and extra copper to keep it in range. Does anyone know of a tutorial that ...
12
votes
2answers
4k views

Why are SMD resistors marked with their value, but SMD capacitors are not?

Why are SMD resistors marked with their value, but SMD ceramic (and similar) capacitors are not? Most SMD resistors, even the very small 0402 and 0603 ones, have their values written on them. Most SMD ...
12
votes
1answer
11k views

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 ...
12
votes
1answer
3k views

What are the advantages of larger SMD pads at the ends of a SOIC land pattern?

I was looking at this NXP TSSOP8 footprint and was wondering why the end pads were 0.600 mm, and the non-end pads were 0.450 mm. What advantages does this have?
11
votes
2answers
4k views

Is it possible to attach leads to surface mount component?

I ordered an op amp to experiment with. I knew this was a surface mount component when I ordered it. I assumed that I would be able to somehow attach leads to it, so I could use it on my breadboard. ...
11
votes
2answers
1k views

MLCC - Can I use high voltage rated caps for very low voltage scenarios?

Is there any important reason why I can`t use high voltage mulilayer ceramic capacitors for low voltage scenarios? For example 50V or 100V rated MLCCs for 3.3V DC applications? I have bad eyes, and ...
11
votes
4answers
3k views

“Upside-Down” SMD LED

The light would shine down towards the board instead of up and away from it. This would be useful where for example the board is being used as some sort of capacitative touch pad with LED indicators. ...
11
votes
2answers
18k views

SMD size 0805 vs 1206

Using SMD to make the PCB smaller is an easy choice but I'm wondering if using mainly 0805 size is really worth it compared to 1206. I don't want to store a mix of both. These are some pro and cons, ...
10
votes
7answers
2k views

Hand soldering SMD 1206 components [closed]

Because I tried to wire-solder a protoboard which failed miserable, I'm intending to order a PCB. However, to minimize the area, I want to use some SMD1206 components. I ordered some basic ones (...
10
votes
3answers
3k views

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

I'm trying to include a micro SD card slot in a project I'm working on and I'm having a little trouble with the datasheet. Unfortunately I don't read japanese. Just wondering what the text says in ...
10
votes
4answers
3k views

SMD ceramic capacitor 0805 vs 1206

I don't know what size to choose. Does SMD capacitor package matter in my case, Is it wrong to choose 0805 package?
10
votes
5answers
18k views

choosing surface mount resistor/capacitors

So I need design a prototype PCB circuit and need to decide on using what kind of surface mount resistors and capacitors to use. But looking at digikey, there are so many types with many variations in ...
10
votes
4answers
6k views

supercap-powered RTC?

I'm designing a ATmega-based microcontroller test board. One of the features I want to include is a Real Time Clock with a Maxim DS1307 IC. Instead of including a traditional coin cell battery backup, ...
10
votes
2answers
2k views

How do surface mount components withstand heat of reflow while through hole components can not?

I have read some online tutorials about soldering through hole components which say that transistors and ICs are delicate components and can be easily damaged by heat. So they recommend to keep the ...
10
votes
3answers
1k views

What is this adhesive tape that comes in some parts?

I think this is a Mylar tape, but why they come with it? I guess its so to make the Pick and Place machine job easier? And why is so common to find them holding cables inside some laptops? Just ...
10
votes
4answers
7k views

Reliability and failure mode of MLCC (chip capacitors)

Recently I've been preparing to manufacture a product which exclusively uses MLCC capacitors across the board. It integrates an onboard buck converter which uses them, and MLCC are also used for local ...