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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29
votes
3answers
9k 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 ...
59
votes
4answers
16k views

Securing electrical cables to holes in enclosures?

Suppose I would like to insert data-cables of varying diameters -- e.g., a cable of 5 mm diameter -- into the 6 mm diameter hole of a plastic enclosure. The wires within the cable are terminated via ...
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 ...
36
votes
5answers
11k views

Why do resistors still use color coding?

I always wondered why color coding is still used on resistors in 2014. Here is Wikipedia's word on the original reason why : Colorbands were commonly used (especially on resistors) because they ...
20
votes
4answers
10k views

Which of these marks signifies Pin 1 on the STM32F (LQFP64)?

I'm using the STM32F105, in a LQFP64 package. It has two circular markings, on opposing corners of the IC. This picture is for a different ST ARM, but the markings and silkscreen are similar: The ...
14
votes
4answers
9k views

Questions on mass-production soldering

Wave soldering I am trying to understand how wave soldering works. Unfortunately the Wikipedia article has has left me unsure about the process: Is the entire board with its components quasi-...
12
votes
3answers
5k views

Soldering heatsink pad on bottom of IC

I am attempting to make a board for the tlc5951 24-channel led driver to drive an 8x8 rgb led array. I have made what I think is a good eagle library for the sop-38 package, but I am not sure what to ...
6
votes
3answers
3k views

Is there a standard PCB Array Size for PCB Assembly?

I am planning on use various PCB assembly houses to get my boards PCB assembled. To minimize process costs, I am told it is best to panelize/array the PCB such that there is multiple boards per array, ...
11
votes
1answer
1k views

What are these spots on the PCB that are by the mounting holes?

When you look at the board, there is a weird part of the PCB right of the top left mounting hole. There is also another one above the top right mounting hole. ****...
16
votes
3answers
29k views

Estimating Assembly Cost

I've got a project BOM costed out and I know my PCB costs. Without sending my project out for quote I'd like to be able to estimate the assembly cost by number of SMT components placed and the number ...
25
votes
5answers
7k views

How do I solder headers so that they always stand straight up?

When soldering headers, usually single and double pins, I flip the board over so the pin rests on the surface and then solder them. They never come out straight. It would be great if someone has ...
14
votes
1answer
4k views

Designing Pick-and-Place-friendly CAD library parts

I'm working on a PCB design with surface mount components to be manufactured by a PCB assembly shop. I'm using CADSTAR, and I had to populate the library with some components, from scratch. I'm new to ...
15
votes
4answers
5k views

OK to connect boards perpendicularly like this?

Are there any disadvantages in using the following method to accomplish a perpendicular board-to-board connection? (i.e., any disadvantages in terms of board manufacturing capability/cost assembly ...
16
votes
4answers
9k views

Feasibility of PCB edge plating?

How feasible is it to edge plate a PCB or at least a portion of one? I've seen it done but as I understand the outer edge is only cut after plating at most fab houses. Is this something that's ...
8
votes
2answers
3k views

Single- vs double-sided PCB assembly costs

I'm working on a new design (still laying out the components) and I have a chance here to reduce the size of the PCB by roughly 40%-50% if I use the other side for a QFP-100 IC (so it's heavy and will ...
8
votes
1answer
1k views

Solder paste stencil application

I am trying to do reflow soldering with a stencil for the first time. I have done some reflow soldering before, but every time I manually applied the paste using a small syringe + needle. These ...
12
votes
10answers
3k views

Is it practical for firmware to be uniquely identified in production

Are there systems available in large scale manufacturing that allow a unique serial number to be programmed into the firmware or some free memory space for each PCB that comes through? I've found ...
12
votes
3answers
3k views

PCB fabrication vs PCB assembly

What is the difference between PCB fabrication and assembly? Some companies like Golden Phoenix list that based on the size of PCB, it outputs a quote. Mine was 2.1 x 1.6 inch. It outputted 29 pieces ...
9
votes
4answers
6k views

How to reliably secure stranded wire in terminal block?

My 18AWG stranded wire continues to come out of the terminal block it's screwed into. What are some ways that I can more reliably secure this in an industrial environment? Strip extra wire and loop/...
6
votes
1answer
782 views

How do PCB fabrication houses make PCBs?

I know the different ways of making PCBs at home, but I can't seem to find a lot of information on how board houses professionally make their PCBs. Is this how they do it?: http://www.youtube.com/...
11
votes
6answers
13k views

Any tricks to attaching a wire or pin to a testpoint?

More and more often, I find myself needing to tear apart a device to seek out and connect to serial pads. These pads typically give me access to the underlying operating system for research or ...
9
votes
3answers
1k views

Anyone know the premise of this PCB assembly note?

The assembly note states: Bake bare PCBs in a clean and well ventilated oven prior to assembly at 125*C for 24 hours. Why is this necessary?
5
votes
4answers
2k views

Very low stacking height PCB connector

I need to stack two PCBs together, but the stacking height is extremely critical. In terms of board-to-board connectors, the best I could come up with was SAMTEC GFZ series. What other solutions can ...
5
votes
3answers
1k views

What kind of breadboard and prototyping board do I need for this right-angle DB25 connector?

What kind of breadboard and prototyping board do I need to fit this right-angle DB25 connector? I'm new to soldering and don't know what the standards are. Additional information on this subject ...
3
votes
2answers
411 views

Moisture Senstive Devices - Shelf Life

I have a bag of DAC7512N digital to analog converter from TI. They are still sealed in the original packing, however the caution notes denote "calculated shelf life in sealed bag: 24 months" and the ...
3
votes
1answer
825 views

From what pitch should I consider ENIG finish

My design (4-layer, FR4, 1.6mm) has a couple of ICs with 0.5mm pitch pads and some LEDs with 0.4mm pitch pads, very small LEDs. Should I consider ENIG (more expensive) or will HASL do the job? I read ...
1
vote
1answer
149 views

What kind of failure would I see in moisture sensitive parts?

I am reflowing a design using an electric skillet. When the uC and LEDs arrived they were in moisture sensitive packaging. They were in sealed bags with moisture indicator cards. After I opened them I ...
0
votes
2answers
97 views

Can I mount LTC6102 on breadboard?

LTC6102 is a shunt resistor current sensor with the following datasheet: http://cds.linear.com/docs/en/datasheet/6102fe.pdf The package Description has come on page 24. If everything is in mm, then ...
-2
votes
1answer
174 views

Arcade stick PCB not working as expected

I am using Logitech precision PCB to make an arcade stick. I am having a problem in button 1 (green) area. While I try to solder button 1 via R2, I had a great difficulty - R2 resistor moved every ...