93 votes
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Why does a commercial PCB need this much rework?

This looks like it's due to a combination of bad engineering, bad management, and cheap labor. Circuits don't always perform as expected when first designed. Even experienced designers make mistakes ...
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84 votes

Do dead weight 'components' exist?

Power your board from a 12V 7AH Sealed Lead Acid Battery. Then hot melt glue your board to the side of the battery. Similar to the ideas shown by @DaveTweed I have mounted prototype parts to a piece ...
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72 votes

Do dead weight 'components' exist?

When prototyping, I often run into the same issue. What I usually do is find a sheet of suitable material that's larger than my board. It can be anything — wood, plexiglass, scrap PCB material, ...
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  • 165k
55 votes
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Why did Axial Capacitors Fall Out of Use in the Industry?

PCB area. Axials pre-dated PCBs, their construction was ideal for wiring to tag strips and valve bases, and they were adopted for PCBs because that's what was available. Example of tag strip ...
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46 votes

Why do resistors still use color coding?

The reason for using color bands on through-hole (axial) resistors is simple -- when they are inserted into the PCB, you can't guarantee their orientation -- there is no top or bottom. So you need a ...
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  • 47k
42 votes
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Why use kapton tape?

If you go through all the trouble to test and qualify something, like tape: check it doesn't unstick after a few years leaving glue everywhere, doesn't shrink, loosen, harden, or crack even if the ...
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40 votes
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What are the 'knuckles' on through-hole LEDs and photodiodes for?

I have two possible explanations: The 'knuckles' are there intentionally to avoid the pins going all the way through the PCB. Most of the times it is not desired that the pins are going all the way ...
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38 votes
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Connecting 10AWG wires to PCB

My general strategy for dealing with vibrating wires is to provide strain relief. I would consider adding holes in your PCB specifically for wire retention, like in the image below. You can use ...
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  • 2,081
37 votes

How to secure cables to a PCB

Zip ties are a good way to provide strain relief for cables attached to a PCB. You lay out a path for the cable on the PCB, and put adequately large holes on either side of this path for the zip tie. ...
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  • 165k
34 votes
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Replace SOT-23 (5 pin) package in production with wire

You can buy zero Ohm links in a SOT23 package. Various connections are available, have a look at http://www.topline.tv/SOT_jumper.html
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  • 5,185
32 votes

Why use kapton tape?

On top of being a good adhesive, it's chemically inert, thermally stable, and does not off-gas when it gets hot.
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  • 1,871
30 votes
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Hand soldering SMD 1206 components

You will likely find that 1206 are actually quite easy to hand solder. When you get used to SMD boards, you will find they are actually quite large. With a standard iron, I find it quite simple to ...
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  • 11.5k
28 votes
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How to remove this component from PCB

You need a lot more solder, so as to cover all the eight contacts and heat them to their melting point. Think "solder pool." Once you pull the component, then you can remove the solder pool using ...
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  • 919
28 votes
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How can I remove the solder bridges?

With solder wick and a soldering iron. Flux will help
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25 votes
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Why are there no BGA chips with triangular tessellation of circular pads (a "hexagonal grid")?

Unless you use via-in-pad, which costs more, you need room to put routing vias in between the pads, like this
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  • 6,048
24 votes

What is the silver strip behind crystal in the PCB?

Here's a picture to help you understand better. The crystal's case can be soldered onto boards to secure them.
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  • 1,700
24 votes

How to solder a stranded wire to a THT hole of a PCB as shock-resistant as possible

If the pcb is an automotive electronics solution, it should not only withstand slight shocks, it should also withstand vibrations and some harder shocks. So you should use only those connectors ...
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  • 2,265
24 votes

SMD 0402 resistor flipped on its side

It's called "billboarding". The IPC standard is mute on the precise reason, but it notes that billboarding may occur during assembly. That condition is acceptable for all three IPC classes ...
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  • 7,220
23 votes

Keeping SMD parts in place while soldering with paste and heat

they suggested was that I use a stencil to apply my paste more evenly. In other words, they blew off my question. No, they didn't. They gave you correct advice. If you have a lot of solder on one ...
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22 votes
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PCB fabrication vs PCB assembly

In PCB world, "fabrication" refers to making the printed circuit board and nothing more. "Assembly" means soldering on all the parts. So, in your example, $100 will get you 29 pieces of copper-clad ...
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22 votes
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What are some reasons for hand painted dots on chips?

These are put there during assembly and test of the PCB and can mean anything the manufacturer wants to mark. Often such a dot is put on a microcontroller, when the firmware is successfully programmed ...
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  • 8,658
20 votes
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Identify these wide ended tweezers

Looks like some wafer tweezer   These tweezers are especially designed for the handling of delicate and fragile silicon wafers, scintillation discs, glass slides, coverslips etc.
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19 votes

How to secure cables to a PCB

Cable ties are great. Just put two through holes in the PCB away from the connector. There are also a variety of flat tie holders that can also facilitate zip ties. These can be pushed in or fastened ...
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  • 63.7k
18 votes

What is the silver strip behind crystal in the PCB?

I wish I could find an image of this, but that is a ground pad. When mounting larger crystals, like the one shown in Peter's answer, it is normal to bend the leads so the can is laid flat on the ...
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  • 45.7k
18 votes
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Double-sided Assembly

You can find some good and relatively modern information in this document. WEIGHT LIMITS FOR DOUBLE SIDED REFLOW OF QFNS Sasha Smith, David Connell and Bev Christian Although their tests were for ...
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18 votes
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Soldering a thin spring steel wire to a PCB

We solder stainless steel from time to time. It needs more heat than I'm really happy bringing to a PCB, and the flux (we use a HCl flux, as you say) will quickly eat the tracks off the pcb if you ...
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  • 12k
18 votes
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Solder SMD on through hole

For DIY project, no problem. If you manufactured a large quantity then you'd have to care about having a low number of defects which means taking care of all the details. But for one-off DIY projects, ...
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  • 59.9k
18 votes
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Can extra long pads cause problems?

No, In fact there are different suggested footprints for hand soldering and for stencil applied paste soldering. https://forum.kicad.info/t/why-different-pcbnew-footprints-for-hand-soldering-smd-603-...
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  • 714
17 votes

PCB fabrication vs PCB assembly

PCB Fabrication involves only manufacturing the board itself. No soldering being done. PCB Assembly is the process of soldering components onto the board. Simply said, fabrication is an easy process ...
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  • 3,000
17 votes

Do dead weight 'components' exist?

Get some large nuts or bolts from a hardware store and glue them in. Not my invention, these have been seen inside commercial products to make them appear more robust.
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