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Questions tagged [pcb-assembly]

The process of mounting electronic components onto a printed circuit board. This can be done manually with a soldering iron, or automatically using a "Pick and Place" machine.

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0answers
31 views

Conformal coating of shielded RF modules

What is the best practice to protect a circuit with shielded RF modules? I have a feeling that conformal coating is difficult since the shield is not sealed.
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4answers
1k views

Fiducial placement

I've read that fiducial should be placed on the corners of the PCB. And that no more 3 should be placed. Below are some questions I can't seem to find online. 1) Would it be a problem if there are ...
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21 views

Help fixing power of a PCB (Akai Mpk249 midi Keyboard) [on hold]

The usb port 2.0 type B female connector used to power the midi keyboard broke off the PCB Board. i soldered a new connector onto the pcb board. When i try to power on my Midi keyboard, I get this ...
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2answers
51 views

drilling SMT footprints for fitting THT parts

I have bought by mistake some THT caps instead of SMD and would like to use them still. They were bought from a supplier who has the bad habit of not answering customer requests. These are 5000h caps, ...
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1answer
106 views

Black Pad. Will heat remove the gold from an ENIG finish?

I have a batch of new PCBs with ENIG (electroless nickel / immersion gold) surface finish. My assembly house has had two unsuccessful attempts at populating the boards. We're trying to troubleshoot ...
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1answer
121 views

Identify dead component in notebook battery

Battery name is GARDA31, based on bq29330 and bq8030. Most probably I killed it myself when soldering by shorting terminals with solder wire :( Controller is alive (communicates through SMbus), but ...
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1answer
79 views

Confused about zero component orientation

I always thought that component orientation in EDA tools (IPC-7351) is separate from component orientation on tape (EIA-481). This made total sense to me: first, PCB design defines rotation relative ...
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2answers
493 views

Specifying BOM substitutions / alternatives with Contract Manufacturer (CM)

I fear this question may be opinion based but I think it has some value to the general community - because this falls into the end of the design phase. When working with a CM, they may have better ...
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1answer
43 views

ESD Protection diode polarity

I'm using the following ESD protection diode: On the datasheet it says: MOUNTING POSITION: Any Does it mean I can assemble it at any polarity? (switch cathode and anode connections)
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893 views

Identifying weird component on PCB

In optical LIN converter PCB there is a weird element glued: A plastic ring with resin/ plastic fulfillment. Is it some sort of local coating or chip-on-board encapsulation? There are no elements in ...
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2answers
69 views

Efficient assembly/fabrication of PCBs differing only in solder jumper configurations

I have a PCB design with solder jumpers which need to be bridged to select specific functionality - say A and B. Half of the PCBs are going to have A and the other half B bridged. Is there an ...
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1answer
43 views

should land patterns match the typical or the maximum part footprint dimension?

I've read that for QFN packages at least, the width of the pads on the board should exactly match the width of the feet on the bottom of the chip. However, the datasheet for the part I'm working with ...
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83 views

Why is my atmega32u4 not showing up as a USB device

I have an atmega32u4 as part of a PCB that I designed. The atmega32u4 comes with a USB bootloader and so I should just be able to plug it into my USB port and have it show up as a device. It doesn't ...
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3answers
125 views

PCB surface shim

We have a PCB with a detector that must be positioned at a particular height above a mounting surface. Our plastic parts are slightly undersized, so we must add some space (0.4 mm) between our PCB ...
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1answer
165 views

How to evaluate the reliability of a PCB-printing service?

I had a talk with a friend the other day who told me that he had many issues with PCB-manufacturers in China (copying his product, long delivery times, bad quality) and that he had to sell his company ...
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1answer
34 views

Minimum distances between box case connectors and PCB surface conductors

I am working on a few kV PCB design with external voltage connectors (HIGH and GND levels). So user interface connectors are thought to be bananas jacks (they support until 7kV but has soldering ...
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1answer
85 views

How to make an electrical connection to thin gold plating?

Hello fellow engineers. I am trying to make an electrical connection with some gold plating. The gold plating is shaped like a rectangle, with dimensions of 3mm x 1.5mm x 0.1μm thick. Here is what ...
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4answers
102 views

Securing mod wires to PCB

I have done a few mods to a PCB with 36 gauge mod wire. Obviously this wire is so thin that it only takes a few bends back and forth to break it. What is the best way to secure this in place on the ...
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3answers
139 views

PCB design for 13A/12V Circuit

I am new to PCB design and am building a PCB circuit powered by a 2200mAH, 25C , 3S lipo battery, the maximum current that will be drawn from this would be 13 Amps. I usually use the trace ...
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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 (...
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9answers
5k views

How to remove this component from PCB

Anyone have any idea how I could remove this component? I've tried blowing hot air, used solder wick, tried to poke the holes with two soldering irons, cut the pins to near the PCB, but it won't ...
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2answers
95 views

How to solder USB-A female socket to PCB?

Sorry I have tried many google searches but can't find anything directly relevant. A USB Type-A female socket, through-hole, right-angle PCB mount has small 45-degree bent pins for soldering the ...
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2answers
99 views

How important is it to track from centre of pad in PCB routing?

When reading through the review comments of a PCB, there was one which raised some questions for me: "Aim to route tracks out of pad centres and in line with the pad, not exiting at an angle." I ...
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1answer
78 views

A recommended way to check a transistor is not burned, without burning other PCB parts

This might seem a basic questions but I am relatively new to circuit implementations and working with PCBs. I suspect that one of my transistors is burned. I am using 2N3904. For example, is ...
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1answer
104 views

Clean vs no-clean flux for high voltage circuit

I have a board that has fairly high working voltages up to 100V with small clearances down to 12 mil between the high voltage and ground or low voltage nets. This is unavoidable because the whole ...
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1answer
75 views

Surface Mount Adapter PCB With Castellated Holes

I have some prototype boards that I would like to modify. The modification includes removing a section of circuit and replacing it with another circuit. My theory on how to do this is to make an ...
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0answers
111 views

How to calculate stray capacitance on PCB

I use a 0.4mm spacing between PCB traces (including 0.4mm space between crystal pads and ground) and I believe that's causing stray capacitance. My circuit board is typical (1 ounce copper on FR4 ...
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8answers
3k views

How can I add “standoffs” to elevate a SMD component above the PCB?

I made a mistake when creating a symbol/footprint for a small (2.0 x 1.6 mm) SMD crystal and didn't notice until the prototypes didn't work. Unfortunately, the boards are tiny and expensive (0.4 mm ...
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0answers
30 views

Using board-to-board pins and crimp receptacles to attach a non-board receptacle to a board

I imagine this is a bit of a stretch, but I'm working through some iterations of a cable harness for a 3D printer. I've considered that a custom PCB may be in order (still on the fence there), but the ...
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1answer
143 views

How to remove kapton tape from soldered parts in bulk?

I have PCBs with SMT nuts (SMTSO2060MTJ) which has been assembled onto a PCB - the nut has kapton tape on top to allow easy pickup for assembly. However, removing the kapton post reflow is proving ...
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2answers
50 views

IC on Breadboard: I have a PCB IC (LTC3115), how to search if it's available for breadboard use?

I am designing a PCB and am using buckboost converter IC - LTC3115. I have tested the component on the PCB and am not getting the required voltage output. My idea is now to check if it will work on a ...
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1answer
957 views

Identify these wide ended tweezers

Working in an electronics lab, we do micro soldering and I came across the tool pictured. No Idea what it's is for. I'm guessing its some tool for holding or removing chips as you rework a PCB. I don'...
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1answer
161 views

Single key not working on DIY mechanical keyboard (xd75re PCB and Switch both work)

I have assembled my first mechanical keyboard using the xd75re PCB. I used a plate mount, and all of the switches were installed without issue (this PCB has hotswap). When I used keyboardtester.com to ...
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1answer
217 views

Connecting top and bottom SMD component pads using via

I am working on a 2 layer board and the PCB will be a double sided job. Some components on the top layer will have exact mirrors on the bottom right under them. My question is, for SMD components, can ...
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1answer
79 views

How to Indicate Bridged Solder Jumper for Production PCBA

If I would like to indicate to the PCBA manufacturer that a solder jumper position is to be "bridged" with a solder blob, what is the preferred way to indicate this? I have thought of the following ...
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4answers
582 views

Beyond what is recommended by fabricators, how far should traces be from SMD pads?

Having followed a fabricator's DRC (this case being OSHPark), this distance between an SMD pad and a trace is considered acceptable (see attached images). However, I wanted to inquire about what the ...
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2answers
513 views

PCB - Ram connectors problem

Currently following an schematic for NanoPI NEO4 to make my own RK3399 board. On their schematic for the K4B4G1646D-BCK0,I noticed for pins DQ1-DQ15 on both chips connect to a randomised list of ...
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0answers
18 views

What do I need to add/remove when changing from a external to internal antenna?

Currently using the nanopi NEO4 schematic to make my own pcb. In their design for wifi/bt they use the F89ETSM13-W2, they connect to a 12pF capacitor and then to a IPX connector for external 2.4GHz ...
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1answer
175 views

Can you tell me more about “re-enterable” potting compound?

I heard the term "re-enterable potting compound", which is a gel-like (possibly hard?) material that can be used to fill electronics enclosures for water intrusion protection and other things. What ...
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2answers
1k views

Double-sided Assembly

I'm going to assemble a prototype PCB which have components on both sides. I have access to a reflow oven with profiling control, solder paste and stencils (from OSH-Park) In the reflow process for ...
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2answers
107 views

Component designators on multi-pcb projects

I am currently working on a project that goes over multiple PCBs for the first time and realised that i don't know what the "standard" or best practice for component designators over two (or more) ...
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1answer
80 views

Is this possible to make a module with both castellations and LGA?

I am trying to decide on a pinout methodology for a module that will be assembled board to board on a bigger PCB. considering the pros and cons of LGA vs. castellations(cut half vias), i was thinking ...
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1answer
104 views

Major causes for routing cut residues on a PCB board and how to prevent it

I am not sure if it is the appropriate to post this question here. I have a question regarding PCB SMT process. We found some PCB board after de-paneling using router cut, some of its residues being ...
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2answers
61 views

How to automatically assemble lithium polymer battery?

I'm redesigning a product for automatic assembly (DFA / DFX). The current product includes a lithium polymer battery with solderable leads, very similar to this: Right now the leads are hand-...
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1answer
106 views

What kind of part is this?

What kind of part on the board below? Or it's a part of another part?
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0answers
96 views

Wire connector with hole only large enough for the conductor and not the insulation jacket

I am trying to find a connector for a PCB that has an aperture sized to allow only the conductor to pass through and not the insulation jacket. I found a drawing here, see part B of drawing below ...
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1answer
50 views

Any suggestions to solve shielded jumpers between different PCBs? [closed]

I've a problem where I got one PCB and then another and I need to get some small power, ground and signals from the other PCB to the other one. The power and signals will also need shielding and good ...
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2answers
120 views

Putting GND on POWER layer

I have a four layer PCB, with a traditional: signal layer, power layer, ground layer and final signal layer. Due to the set up with the power rails, there are some large spaces on the power plane ...
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1answer
230 views

SMDs on bottom side of board with THT components?

I'm designing a PCB for factory production and I'm not sure if placing SMD components on the bottom side of the board, which also contains THT components (pin headers and buttons, they're all on the ...
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4answers
421 views

What PCB Plating do I need to use Exposed Copper Pads with Pogo Pins?

I am designing a PCB that will have some Mill-Max pogo pins make direct contact with exposed copper pads on the PCB. This will have many connects and disconnects, think hundreds to thousands. I know ...