[HN Gopher] Cheap PCB story
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Cheap PCB story
Author : hardenedlinux
Score : 77 points
Date : 2021-02-18 07:22 UTC (15 hours ago)
(HTM) web link (github.com)
(TXT) w3m dump (github.com)
| antattack wrote:
| "0201 package is too small. 0603 is more convenient for manual
| welding."
|
| I much prefer soldering 0402 and 0201 components than larger SMD
| parts, including 0603. What's needed is soldering paste, liquid
| flux and heatgun and macro lens attached to a phone for
| inspection.
|
| What's nice with hot air soldering tiny SMD components is that
| you don't need a lot of heat when soldering, desoldering and get
| zero tombstoning.
| stingrae wrote:
| you can definitely hand solder 0201s without solder paste, if
| you have thin solder, a thin tip (on your soldering iron) and
| decent magnification. I have successfully done 01005s with this
| method.
| amelius wrote:
| The nice thing about larger SMD components is that you can
| route interconnect between the terminals. This way you get a
| "free" layer in the form of components.
| kube-system wrote:
| I really like using a USB microscope for taking a close look at
| PCBs. They're pretty cheap, free up a hand, and you can put the
| picture on a large monitor.
| nerfhammer wrote:
| pro-tip: your phone's magnifier app can be used as a
| perfectly good digital scope, you just need something to hold
| it up with.
|
| ios: Settings > Control Center > Customize Controls >
| Magnifier
| iamflimflam1 wrote:
| The AMS117 should really have tantalum caps on the output for
| stability - though I must admit, I have got away with ceramics on
| my own boards. Reduces the BOM cost significantly.
| sbierwagen wrote:
| >It's feasible make multiple smaller boards on the bigger ones by
| panelizing the PCB. The joints between the boards are specially
| processed, which is easier to divide later. Rails can be added
| around the boards for fixing during processing.
|
| I've seen at least one PCB shop that asks customers not to
| panelize for small lots, so they can mix layouts from several
| customers and get better packing efficiency.
| StavrosK wrote:
| I have too, but when I have an option between 1x the price and
| 1x the boards and 2x the price and 9x the boards, I usually
| pick the latter.
| leoedin wrote:
| Even for runs off a few hundred PCBs all the PCB assemblers
| I've worked with prefer to do it themselves. They know their
| machines much better than I do.
| Torkel wrote:
| I've done a similar journey during this lock down year. I started
| off with a small design of a custom latency measurement thingie
| that was a "rats nest" with wires and components soldered to an
| arduino. Converting it to a PCB, I used easyeda.com. I recommend
| that over KiCad, which I later tried but it's clunky compared to
| Easy EDA. KiCad feels like blender before the re-work they did.
| Or InkScape. Opensource has such incredibly crappy ui:s
| sometimes... Yay Blender!
|
| First batch was bare PCB from jlcpcb.com and components from
| digikey. Handsoldered it. And it worked!! OMG, the JOY!! I highly
| recommend to do some simple own pcb design.
|
| Then I did v2: STM32, ws2812b, tiny smt components. I used jlcpcb
| assembly service, complemented with some components they didn't
| have in their (limited!) smt library. Bringup of the first stm32
| was a bit of a nightmare. I had missed pulling a boot0-pin low
| (~2 days wasted). A co-worker is madly in love with rust and made
| me write the whole code in Rust (2 weeks maybe, not "wasted" per
| se - but oh man can embedded rust be... a lot of fun...
| sometimes). Missed pullups on i2c lines. So much learning on
| version two.
|
| Version three I tried to keep is simple. But also smaller. I had
| an idea to use 3.5mm audio cables for power and data. I thought
| SMD audio cable contacts would be rugged. I was wrong - they came
| off. I had bought a syringe with solder paste and one with flux.
| Totally recommend getting a flux syringe! So good! But that
| solder paste... I maybe didn't grok how to use it, but it did not
| reflow well enough to make the audio cable contacts stay put when
| used.
|
| Got version four a couple of weeks ago. Doing pcbway.com with
| them doing the full smt and through hole soldering. This is how
| to do it! I do not at all understand why all are raving about
| jlcpcb.com - they have such a limited library. Why not make a
| proper pcb shop solder it all? It doesn't cost that much more. If
| time is a factor it is a lot cheaper. V4 feels like a winner -
| shipping them out to customers now.
|
| I've also done some other boards during the lock down, such as
| control boards for RC cars in three versions, and three versions
| of an Ethernet connected microphone. I'm still on EasyEDA, but as
| mentioned I now let pcbway do soldering of everything.
| bschwindHN wrote:
| I recently went through the process of designing a board based on
| an STM32F411RE. I highly, highly recommend the YouTube channel,
| Phil's Lab. With his tutorial I was able to produce a working
| board on the first try.
|
| https://youtube.com/c/PhilS94
| peter_retief wrote:
| This bridged my knowledge needs perfectly, I have made a few
| PCB's but it was a struggle. Thanks!
| nippoo wrote:
| Great to see people learning and designing PCBs themselves - it's
| a fun and rewarding hobby!
|
| There are a whole bunch of improvements I'd suggest with this
| particular design and article though: (also, doing six respins
| for a board this simple is a bit painful, and I'd encourage
| people to submit their layout to someone for a design review
| before going through this many iterations - I've reviewed things
| for friends in exchange for a pint of beer!)
|
| - this board has no ground plane, and no return paths near the
| data traces - this will be an absolute EMI nightmare and also
| signal integrity will suffer. At very least, dedicate the bottom
| layer to ground (and flood-fill it) - the return path for digital
| signals (and anything above a few KHz) is directly below the
| signal path - see https://incompliancemag.com/wp-
| content/uploads/2017/04/1705_....
|
| - (the clock design, in particular, is completely against ST's
| recommendations - there's no ground plane and traces running
| directly underneath!)
|
| - panelisation: as others have mentioned, even for large-scale
| production runs, the PCB manufacturers will do a better job of
| panellising themselves, and can stack your boards in amongst
| other boards on the same panel if you're not taking up a whole
| panel.
|
| - unless you've got a good reason to do it, having a serial
| programming interface with a serial/USB chip isn't the easiest
| way of doing it - exposing SWDIO/SWDCK/SWO to a suitable
| connector and using an ST-Link in-circuit programmer is generally
| an easier and more space-efficient way! They seem to have gone
| that way in the last couple of revisions.
|
| There are a bunch of other things I'd probably do differently,
| but this is all to say - if you do decide to take up this hobby,
| please do get your designs looked at by someone knowledgeable,
| you'll learn a lot that way!
| amelius wrote:
| I didn't know KiCad can place components at a 45 degree angle.
| nrp wrote:
| You can actually place components at arbitrary angles, and even
| do so programmatically through the scripting interface.
| hriquelme wrote:
| I'm going to create my first commercial PCB, thank for post your
| complete journey, lot of useful information.
| shadowpho wrote:
| Please just use jlcpcb, they do PCB and SMT at very cheap
| prices.
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(page generated 2021-02-18 23:01 UTC)