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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35 views

Identify part number of a surface mount device

I have a commercial data logger to gather data from a heat flux sensor. The sensor puts out a signal in the microvolt-range. This signal is amplified before it gets logged. I think that I've located ...
1
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1answer
54 views

DIY SMD - options for covering exposed vias?

I printed a PCB + got a kapton stencil made for a project I'm working on. One of the components is a BGA chip, and has vias close to the bga pads. The vias on the board don't have solder mask on them, ...
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2answers
60 views

1N4004 SMD replacment [closed]

Please help me, how do I find the corresponding equaivalent of 1N4004 Diode. Also as not everything is available in local market here in India, I would appreciate, if there are some well known ...
8
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2answers
386 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. ...
1
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2answers
185 views

How does power dissipation for surface mount components work?

I know that with usual through hole components we can attach heatsinks etc. But how does it work with surface mount components? Is having a copper plate around the component the way to go? How do we ...
2
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1answer
78 views

Why are SMD Diodes different Packages than Resistors and Capacitors?

I was looking for SMD Schottky Diodes on Digikey, and they all come in weird packages like SOD-123. There were some that were 1206 or 0805, but they seem fairly rare. Why is this? The only difference ...
4
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2answers
84 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 ...
6
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2answers
143 views

Soldering guidelines for freezer applications?

I'd like to do a home project where I take temperatures inside of my freezer and inside liquids. Liquid-compatibility aside, I'm mostly curious about whether or not anyone can recommend some best ...
3
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1answer
110 views

What standard governs the dimensions of SMT chip resistors and capacitors?

I am aware of the JEDEC registered outlines, which define the standard mechanical dimensions and tolerances for a wide variety of solid-state packages. However, these standards do not appear to cover ...
0
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1answer
187 views

Soldering underside pads of Teensy 3.1

I have to place this Teensy 3.1 on a PCB, I am planning to make the PCB such that it has headers on which the whole Teensy will fit. Essentially, it is similar to making a shield like we make for ...
0
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2answers
88 views

Rule of Thumb for PCB pad sizes of SMD devices?

I am trying to make a PCB for the first time and am concerned about the sizes of the soldering pads over the actual dimensions that I should realize on the board. That is, with the following diagram: ...
1
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0answers
53 views

Standard for right angle SMD LED?

I'm trying to specify a SMD LED which has "right angle" mounting, ie edge mounted, with the light going parallel to the horizontal PCB. I need a RGB version (tri-color). Example. As usual, there ...
4
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3answers
248 views

0402 Land Pattern

I'm working on the second iteration of a board which uses quite a lot of 0402 caps for decoupling around processors. On the first version of the board I had complaints from the subcontractor that ...
2
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1answer
115 views

LM348 replacable by LM358

I want to give SMD soldering a try and therefore I was looking for some useful circuit (no LED-blink-crap) I could build more or less easily. So I found a nice DIY function generator here. It uses ...
3
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1answer
44 views

Physical stability of different surface mount footprints

While looking for rotary switches to use as user inputs to a processor, I came across these three footprints: I'm considering using a surface-mount part for board layout considerations, but ...
1
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1answer
86 views

Identify and replace a resistor [closed]

My APC UPS stopped working. I have had it for many years and it was serviced once by APC while in warranty and never opened again. Now since it is not in warranty anymore I opened it and saw two ...
0
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1answer
58 views

Building a SMT footprint for a MSOP

I'm putting together a board and it's requiring a footprint for a 16 lead Plastic MSOP. Usually I try to dig around and find a manufactures recommended footprint and try to stick with that. I figure ...
2
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2answers
98 views

How to find a datasheet for a part that doesn't exist on the manufacturer's website?

While bored recently, I decided to take apart a few old pieces of electronic equipment and attempt to reverse-engineer them. I've been doing pretty well, but I've come to an IC that I can identify ...
7
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2answers
372 views

Help identifying pwm controller “67A”

I am repairing a battery charger that uses two power supplies. TH20594 (couldn't find any info on that either) controls the primary PSU, while the mysterious chip controls the bootstrap/standby supply ...
2
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1answer
85 views

Are thermal reliefs on SMD pads beneficial when reflow soldering?

I know that thermal reliefs have benefits when hand-soldering through-hole components. For some high-frequency or high-current components, I understand why it's a good idea not to use thermal ...
2
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2answers
58 views

differences between different footprint surface mount RLC components

This is my first question here and I am new to board level digital design(I have years of experience on programming development boards though). So here is my question, what are the differences ...
11
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4answers
837 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 ...
2
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1answer
105 views

Thermal calculation for a D2PAK with a SMT Heatsink

I am trying to calculate the junction temperature of a D2PAK FET that is dissipating 5W. The junction-to-case thermal resistance is 0.4 C/W. The junction-to-ambient (PCB mounted, steady state) ...
2
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1answer
111 views

PCB component with abbreviation SR1

I have a laptop battery pack with a fried component (visually fried) that has the appearance of a large surface mount resistor (only 2 connectors). It has the PCB abbreviation next to it of "SR1" ...
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2answers
139 views

Easiest way to solder connections to all the legs on a surface-mount chip?

Recently, I went through the process of soldering wires onto the legs of a TQFP chip (~0.8mm pitch) which has already been mounted on a PCB. This is a project where I am doing some modifications to ...
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0answers
42 views

BGA reflow and RTV

I am having trouble with a board at work that we need to replace a BGA on but near the part is a section covered in DOW Corning 3140 RTV. We are using and Air-Vac DRS25 for this process. when we run a ...
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1answer
127 views

How to identify value of a surface mounted fuse

I have a PCB from a WIFI router and there is a lot of little surface mount components. I am looking for fuses, some of them might actually be them. My question is how do I identyfy them and find out ...
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1answer
41 views

Wire wound inductors naming

I see some SMT wire wound inductors are named like 3R3 or 4R5, much like a resistor, why so? I expected them to be like 4H5.
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2answers
76 views

How to bypass or replace a defective SMD switch?

I have a wireless keyboard with a defective on/off switch. The switch has a little play, and it's closing the circuit only when it is almost pushed to the extreme position for on. If 0 represents the ...
3
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2answers
251 views

What does WFQFN stand for?

I saw this as a package type for an attiny microcontroller in the digikey catalog. I'm pretty sure that "QFN" stands for Quad Flat No leads. However, I'm not sure what prefixed "WF" means. Is there a ...
3
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1answer
264 views

Definitive land pattern for 0603 SMD capacitors?

So, I am trying to figure out what pad size to use for 0603 (imperial) SMD capacitors. The datasheet for the particular capacitors I plan to use provides part dimensions but does not recommend a land ...
2
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1answer
102 views

Pick and place machine + AAA battery holder?

Say I design a two-sided PCB. I want the bottom side to have just a 2xAAA battery holder. Could a pick and place machine handle this or is it out of the question? What happens when the top side is ...
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1answer
189 views

What are these components?

I have an old mobile phone circuit board. I have several questions of components on this board. look the board: What are the components shown with red squares? are they filters(I think, I'm not ...
3
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1answer
590 views

Advantage or disadvantages of SMD over Through hole design in high frequencies?

I know this is an elementary question. I know that SMD design has the advantage of smaller board size but I dont know which design works better in higher frequencies.
3
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2answers
245 views

How can I program a surface-mount Atmega328?

I want to program a surface-mounted Atmega328 before soldering it to my board. I have an AVR Dragon board that is capable of ISP. This works fine with DIP Atmegas where I can just pop them into a ZIF ...
2
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2answers
152 views

First pin of this SMD chip?

I just bought 74HC595 shift register IC and I'm having trouble finding the first pin. There is no first pin mark anywhere on the chip as you can see below.
5
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2answers
177 views

Standard packages for compact SMT crystals

There is an old and bog standard form factor for SMT crystals - HC49/US. The problem is that HC49/US takes a lot of real estate on the board. It's 12mm long. Another problem with crystals and ...
8
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2answers
255 views

How to deal with LFBGA217 package when building prototype boards by hand

I am involved in a project in which I need to create a few prototype boards that will use the AT91SAM9G20B-CU processor in the LFBGA217_J package. Because this is ...
2
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0answers
193 views

SMD Code & Manufacturer Part Number?

Can anyone identify the SMD Code and manufacturer part number of the following device? Code t9GRID Review photo
4
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2answers
140 views

5V Regulator Power Dissipation

I am using a 5V regulator (LP2950) from ON Semiconductor. I am using this for USB power and I'm feeding in 9V from an adapter. USB requires maximum of 500mA right? So the maximum power dissipation in ...
2
votes
1answer
138 views

Is there a pitch limit to applying solder paste through a PCB stencil by hand?

I've ordered two stencils from two different companies, two different materials. Both times I've been completely unable to effectively apply solder paste to the pads of a QFP-64. I end up with a mess ...
6
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3answers
253 views

Universal smd pad size, bad idea?

I'm working on an open source filter design where the PCB can be reused for many future designs. It is based around a Sallen-key filter since a few changes to the capacitors and resistors can change ...
0
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1answer
92 views

What effect do different SMT stencil materials have on results?

I have a PCB with 20-mil pitch SMT pads for a QFP-64. I ordered a stencil for it, which is made of some flexible material. I haven't had much luck with it, I suspect because the material is so ...
1
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1answer
103 views

Is the shape of (SMD) pads relevant?

SMD pads come in basically two shapes: rectangular and rounded rectangle. Does either offer advantages? For instance for etching, or HF signal integrity?
0
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3answers
99 views

What is the optimal way of clearing solder from surface-mount PCB pads for rework?

Say I have an assembled PCB with a QFP package on it. This device gets damaged and I need to replace it. Getting the device off is straightforward, but now all the pads have solder blobs on them. Is ...
5
votes
2answers
229 views

Are SMD components sometimes glued?

I just tried desoldering an SMD receptacle off a mass produced main board of an IBM ThinkPad X41 laptop, but that beast stuck to the board like glue, and I destroyed it. Is it possible that the ...
0
votes
2answers
223 views

Why can't desoldering wick be used to desolder SMD?

I've read and heard (in German, as spoken in Austria) that desoldering SMD components with desoldering wick does not work. Why? Side note: I wouldn't care if the PCB is destroyed. I want the ...
2
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1answer
135 views

Unusual Surface Mount Package (with notches) - how to mount / solder?

I have recently acquired an electronics component that I was expecting to have a "normal" surface mount foot that I could solder. Instead, what is has is a very thick section that has a 0.50mm ...
1
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1answer
220 views

SOT23-5 Package vs SOT23-5L…Differences?

I'm designing a board which uses an LDO that comes in the SOT23-5 package. I have these parts in my possession, and on the part label (from Digikey) it displays that it is a SOT23-5, which makes ...
2
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1answer
77 views

Altium - having trouble pouring copper

As you can see above, I'm trying to make a copper pour connect all the GND nodes. I could run a track and define its width to be huge (accomplishing the same thing) but I don't really think that's ...