Questions tagged [dfm]
Design For Manufacturing - Principles and techniques that are used to ensure that a product is more easily manufactured, has higher yield during manufacture and/or exhibits lower cost of manufacturing. May be accomplished through choice of components, extra circuits for testing through to mundane issues like space for fixturing and labeling amongst many other techniques.
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Is there a rule of thumb or an IPC standard for reducing (windowing) solder paste deposition on exposed pads?
I am creating a footprint for a 24-pin QFN package with exposed thermal pad. Sometimes manufacturers will provide solder paste mask guidelines in addition to metallization for the landing pattern, but ...
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What determines the choice of maximum material condition (MMC) versus least material condition (LMC) when designing a BGA footprint?
I am evaluating the IPC-compliant footprint wizard in Altium Designer. One of the steps is to determine the pad size relative to the nominal ball diameter:
Related to this topic, an answer provides a ...
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What is the purpose of these unusual IC footprint features?
I am working on creating a footprint for the MAX25254 buck regulator and am puzzled by several inconsistencies which are proving annoying:
Inconsistent pad sizes
Seemingly unnecessarily complicated ...
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Are my tracks too close?
I'm working on a digital circuit that I plan to run at ~1MHz. After finishing the PCB I looked back at my work and saw that my tracks are quite close.
For a size reference, the tracks are 0.254mm ...
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TQFP fanout for DFM / AOI
I've often heard a couple of "good practices" for TQFP/QFN ICs fanout:
Do not route corner pins at 90°, instead the track must come straight to the pin:
Do not short the signals directly ...
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Surface Treatment choice for edge connector
So I have an edge connector that according to Alibaba Chinese salesman has tin-plated terminals (datasheet a bit unclear).
I am making a product where I am inserting a PCB into an edge connector and I ...
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Does the PCB have to be thinner than through-hole pin length?
If I have a part that has pins that are 1.2mm long. Can I use a PCB that is 1.2mm thick or does it need to be even thinner than that?
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Best way to heat sink many resistors
I have a PCB design with a long row of 1206 power resistors. Although only a few of them will be active at a time, they can dissipate up to 1 watt each, so I would like to heat sink them. If they get ...
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Local fiducial placement
I'm working on a prototype that has a few fine pitch (0.5mm) components. I'm thinking about adding local fiducial marks for these components as an afterthought. My idea was to place them close to the ...
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Best practice for ICT test point locations
While I have found a few resources (here here here) describing the coverage (strive for 100 %!), distribution (avoid clustering, at least 100 mil apart, away from tall components), and size (40 mil if ...
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Understanding Transition faults
I learned that the transition faults model checks whether data transition meets the clock or not
Transition Faults : Assumes large delay defect concentrated at one
logical node, such that any ...
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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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How close can BGA packages be placed to each other? [closed]
I'm wondering if there is some rule of thumb about how close different BGA packages can be placed to each other. What limits that besides pick and place accuracy?
I'll ask a few board assembly ...
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SMD LED Orientation From Top
Is there a way to determine the orientation of the LED in the image below?
The blue squares in the corners seem like they are denoting the orientation however it's not marked in the datasheet.
This ...
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Do 0402 chip component need solder mask web between the pads?
In my board, all 0402 parts are using gang solder mask.
The pad to pad distance is 10 mils. Is there any risk of solder short?
Do I need to suggest applying solder mask web between the pads for all ...
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Balancing copper on inner layers of PCB
A similar question was asked - What is Copper Thieving and why use it?
And my question originates from the comments of the answer in the linked question.
I have read and understand that to help the ...
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What does this statement about fiducials mean?
Found this slide and I didn't understand the last statement.
All fiducials should have same image one layer down
Are fiducials not top/bottom layer registration targets during assembly ?
Are/Can ...
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PCB pads different diameter on top and bottom
When I had a DFM review on a board I have designed, the feedback was that the pads on layer 1 (top) needed to be reduced in size, to:
"avoid the issue of copper temperature taking during wave ...
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Why are reversed geometry (0306, 0204) capacitors not used more often?
It seems that reversed geometry or low inductance ceramic chip capacitors (MLCCs) are simply better in every spec than regular geometry, and may allow using just one value to bypass instead of two (eg ...
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PCB Design Software for work collaboration and minor alterations? [closed]
In my workplace I need PCB software to make minor changes to PCB layouts from our design partners and also to review and suggest changes to incoming designs.
Our design partners use x and y. X is ...
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Symmetry in routing
I'm moving a design to an 8"x6" panel, and got thinking as I drew the route layer(white).
The cutouts on the right two boards will be routed out. The left cutout will stay with the frame. During ...
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Via to Pad Clearance
Is it possible to put a via right next to the component pad it is connected to? In other words, if a via and a component pad are on the same net, can they touch as in the image below (red=top layer, ...
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Pogo Pins for 1.5mm Pitch Test Fixture
I'm working on a design and am going to source a smaller pcb and solder it to my design.
Before using the sourced board I'm wanting to test it and so I'm trying to design a test fixture similar in ...
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Are acid traps real? (2014)
Some people online say that acute angles in trace routing will cause these problems:
"Acid Trap" - PCB etchant gets stuck in the corner, and eats away too much, causing open circuit
"Peelable" - ...
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How to make a device in miniSD or microSD form factor?
I would like to design and get produced a device in miniSD or microSD card form factor. This is not actually a memory card, it just uses that connector. There are other devices like that, for ...
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How to go from newbie to manufactured?
I'm a software guy who wants to get into the hardware side of things so I can enjoy the same creativity from software design in the physical world.
I've found plenty of posts here regarding how to ...
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How close is too close for traces on a PCB?
Are these traces too close for conventional PCB manufacture? DRC check advises against it, but I haven't filled out all the settings for it.
For scale, the resistors are all 0603.
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