22 votes

Why is it so hard to find component footprints?

When I was working as an engineer, I wondered the same thing, which is why I decided to create SnapEDA. SnapEDA is a CAD library of 25 million electronic components, for which we provide PCB ...
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  • 354
22 votes
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Why would metal from a pad be *underneath* the solder mask in a footprint specification?

There are two ways of defining the "active" area of a surface mount footprint: SMD and NSMD - that is Solder Mask Defined and Non-Solder Mask Defined. It is unusual to see both in one footprint, but ...
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  • 55.5k
20 votes
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Why is it so hard to find component footprints?

You've discovered the dirty little secret of the EDA industry: Thousands of engineers everywhere reinvent the wheel every day - they all create many of their sch symbols & pcb footprints from ...
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  • 4,041
18 votes
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What component does the 'coupon' label refer to in terms of PCBs?

Most of us think of a coupon as a small tear out thing in a magazine or sales mailer that is used to save money when you buy something. In the PC board world these were generally added to the ...
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18 votes
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THT: What is a squared annular “ring”?

It’s just a quick and easy way to distinguish which connector pad is pin 1. Particularly when there is no silkscreen present or just when routing the PCB.
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  • 8,165
17 votes

Why do KiCad's library footprints for 0402 resistors and capacitors have different pad sizes?

IPC-7351 specifies wider land patterns for chip capacitors than chip resistors, because capacitors are usually taller, so the solder fillet "wants" to extend further laterally. Using the slimmer ...
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  • 6,057
13 votes
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How to create footprint from IC diagram when no recommended layout is given?

Method #1: Tools->IPC Footprint Wizard->QFN and go from there. This wizard is based on IPC-7351 standard, the main standard for footprint creation. The standard is not straightforward if you want ...
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13 votes

‘One for all’ standardized land pattern v.s. specified land pattern in datasheet

The correct footprint to use for a component land is 'one that works'. This isn't so flip as it sounds. What does a land pattern have to do in order to 'work'? a) it must connect each component ...
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12 votes
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Pads in IC's corners

They are there to allow for wave soldering. As the solder flows on the legs, any excess can end up on those pads, not shorting out the pins of the IC.
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  • 606
11 votes

Why there is IPC Level A and B?

The answer provided by asndre refers to three levels of density for laying out PCBs, which are referred to in IPC-7531 (original, B and long-awaited C) as Levels A, B and C. I think the question ...
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10 votes
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‘One for all’ standardized land pattern v.s. specified land pattern in datasheet

In my experience, you can safely stick to the IPC standards, which by the way also suggest three different footprints for each part: Least, Most, and Nominal. It is up to you which one to select, ...
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  • 2,694
9 votes
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What are the contact pads near the ATmega32 chip on the Arduino Yun?

They look like the footprint for an alternative package, probably the TQFP-44 variant. Having both footprints: QFN (the leadless package that is installed) and the alternative TQFP variant allows a ...
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  • 4,138
9 votes

What does "V.A." mean in datasheet dimensions?

This is not a standard dimensioning abbreviation according to any standard I'm familiar with. Instead, I suggest the (in 20:20 hindsight, obvious) meaning that the dimensions given refer to the ...
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9 votes

Why would metal from a pad be *underneath* the solder mask in a footprint specification?

Looking at the current rating of the internal switches (3.6A) and the device pinout, the use of soldermask defined and non-soldermask defined pads seems to be correlated with one thing: the high-...
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  • 2,808
9 votes
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KiCad 5.1: New footprint from existing footprint

Short answer: Yes. @Indraneel's comment is exactly correct. Long answer with steps: First create a new library into which you want to save the modified footprint. You do this from the File menu. ...
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  • 3,759
9 votes
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What does the minus sign mean in measurements in datasheet footprint drawings?

It looks to me that it means four 0.7 mm wide pads. Another way of writing it would be 0.7 (4 places)
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9 votes

PCB Footprint Design Dimensions

The 2-2.00 dimension (your Y) is 2.00mm, but it applies to two identical holes (2-) on the datasheet. Only one of those holes is dimensioned for length, the other is dimensioned for width, to avoid an ...
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  • 144k
9 votes

KiCad Gerber vs Layout Error

There are several areas that surround (or encompassed by) the pads: trace clearance (or just clearance), pad clearance, solder mask clearance, solder paste clearance, zone fill clearance, thermal ...
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  • 10.8k
8 votes

SMD LED polarity marking: is the cathode marking standardized?

It is entirely per component manufacturer, and when the PCB is manufactured some companies will ask that component placement overlays are given with designators are provided and polarity marks for all ...
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  • 6,198
8 votes

How to display a custom parameter value in the PCB footprint of my Altium component?

There is one way, some kind of workaround. But you have to give up the Component's comment field because we will use this to show a custom parameter on the PCB along with the footprint. Add your new ...
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8 votes
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What standards cover foot prints for standard part packages?

It's the IPC-7351B - "Generic Requirements for Surface Mount Design and Land Pattern Standard" The document only provides recommendations; there is no enforcement. However, more and more ...
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  • 16.4k
8 votes
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What does "V.A." mean in datasheet dimensions?

After looking into the linked LCD datasheet and answers here, I looked into other display products of the same company NEWHEAVENDISPLAY. And the interesting thing I found is apart from V.A. they use ...
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  • 2,223
8 votes
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Varying SMD Footprints in Library

Notice how the pads on each are different. These usually follow the different recomendations (usually from IPC) for high density, low density, etc. Low density has bigger pads which will give you ...
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  • 12.2k
7 votes
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VSSOP-8 Package Footprint

Adding to Sanjeev's point, below comparison indicates that Land pattern can be shared. If still in doubt, ask TI. below is Land Pattern of OPA4170.
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  • 9,001
7 votes
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How bad is it to places vias under a QFN thermal pad?

I would not go with this. Small designs will not necessarily heat up that much, but running an exposes pad so close to your traces is risky. Depending on volume, you will get some boards where part of ...
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  • 806
7 votes

How to interpret BGA package for creating footprint

You will find that both diagrams actually have exactly the same pin mapping, though it is slightly obfuscated. The first thing we have to do is identify which side is which in the diagrams. In the top ...
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7 votes
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Strange footprint labeled PJ## on laptop's motherboard

Solder Jumpers Reason not sure why so big but yes they are solder jumpers for sure. sometimes used to isolate a few MCU pins which might be conflicting otherwise connected during programming (...
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  • 9,001
7 votes
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Unrecognized IC Package Style

This might be the drawing for SOT804-4, which you are looking for. The land pattern is on p.3 . The second row isn't soldered to the board, if I'm reading the drawing correctly. I'm guessing, each ...
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  • 36.1k
7 votes

Footprint is Driving Me Crazy!

You aren't meant to provide any drill holes for these features. They are meant to rest on the top surface on the top surface of the board, allowing the actuator to be accurately located relative to ...
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  • 121k
7 votes
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Trouble reading a variable inductor (tunable RF coil) datasheet

Usually these days we lay out boards as if we were looking down through the board from the component side. Many years ago, with single-sided boards, it was not uncommon to lay out boards using sticky ...
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