[HN Gopher] DIY Through Hole Plating of PCBs (2017)
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DIY Through Hole Plating of PCBs (2017)
Author : todsacerdoti
Score : 54 points
Date : 2021-03-13 05:32 UTC (1 days ago)
(HTM) web link (blog.honzamrazek.cz)
(TXT) w3m dump (blog.honzamrazek.cz)
| amelius wrote:
| I wonder how desktop PCB printers like the Voltera V-One make
| vias and through-holes.
| gh02t wrote:
| They don't, at least not conductive ones. Volterra drills
| through holes but they aren't conductive. They recommend using
| rivets or less preferred is filling them with conductive ink
| and baking, but that's a huge pain and I imagine most people
| just use a piece of wire instead or try to avoid vias
| altogether. Othermill works the same way.
|
| Usually you want to design your board around this limitation,
| which is why I generally don't recommend them for people
| looking to prototype PCBs with the intent of having them
| professionally manufactured later. IMO their niche isn't really
| as a replacement for a manufacturing service, more as a quick
| turnaround tool that lets you make one-off boards as needed.
| uuidgen wrote:
| They don't. You have to rivet vias which, while relatively fast
| when compared to soldering them, is pretty expensive
| (~$20/100).
| lmilcin wrote:
| I don't think this pays off for most people. Most circuits can be
| prototyped without printing boards. I use a combination of
| generic function boards, adapters for SMD components, DIP
| versions of components, etc. to be able to easily put together a
| working prototype on 100mil grid.
|
| Worst case, I use dead bug technique for a non standard component
| I don't have adapter for.
|
| For large projects I might be splitting the problem into multiple
| separate functions and have a prototype of each function
| separately, later to integrate all to a single board.
|
| For example, I am currently working on a controller that will
| control a heater, pump and couple of valves based on input from a
| bunch of very sensitive temperature sensor. I have two separate
| boards one for temperature measurement and one for 1kW of AC
| through bunch of relays, triacs, SCRs and so on. Each relay,
| triac and SCR is mounted on its own generic small boards
| (something like this: https://pl.mouser.com/ProductDetail/Chip-
| Quik/PA0185?qs=gjT6...), soldered in turn onto larger generic
| board (for example https://pl.mouser.com/ProductDetail/BusBoard-
| Prototype-Syste...).
|
| All these are hooked up to a Nucleo board where I develop my
| software.
|
| Once I have working prototype it makes no sense to spend time
| trying to make a half-assed board. I would very much prefer to
| design much better looking, much tighter tolerances board based
| on tolerances accepted by the PCB manufacturer and wait for it
| for couple of days.
|
| If I really needed to work on the circuit in the meantime I still
| have the prototype. While waiting for a nice shiny board I can
| still working on software, find bugs, etc.
| Stratoscope wrote:
| > dead bug technique
|
| For anyone unfamiliar with the term, dead bug construction is
| where you put the integrated circuits upside down (like a dead
| bug) and solder wires and other components directly to their
| leads. Here are some photos and discussion:
|
| https://www.google.com/search?q=dead+bug+construction
| lmilcin wrote:
| Most those photos are other techniques. What I call dead bug
| is specifically to solder chip to a prototyping board by
| inverting the chip and soldering wires directly to the chip
| pads.
|
| http://dangerousprototypes.com/blog/2012/11/15/fine-pitch-
| bg...
|
| I don't put photos of my prototypes on the Internet, but this
| is how it, more or less, looks like (only I use board with
| holes):
|
| http://dangerousprototypes.com/blog/2012/10/24/who-says-
| bga-...
| askvictor wrote:
| > As bottom line - I am not going to start make all my PCBs at
| home. I don't think it is worth it in 95 % of the cases. I
| tried this experiment for fun and for educational purposes.
| minxomat wrote:
| A low tech and quite effective way to do vias is via micro
| rivets. They're popular for CNC'd PCBs, e.g.:
| https://wegstr.com/riveting-set-for-PCB-vias-0.4-mm?search=R...
| (No endorsement, just for the pics)
| glitchinc wrote:
| Along the same lines, Favorit makes a press (along with tools /
| dies and rivets) that takes a lot of the guesswork out of
| through hole plating. I've been a long-time user of the press
| after getting frustrated with the "solder a paper clip" method
| of through hole plating, and its greatly increased the yield of
| my CNC PCB projects.
|
| https://www.vpcinc.com/Category/Favorit-Through-Hole-Rivets-...
| sigmaprimus wrote:
| >>>"There's however one limitation - my vias are soldered
| through-hole wires." Why is this a limitation?
|
| Anytime I lifted a trace or needed to repair a via, I just coiled
| up a 24-26 Awg single strand wire and stuffed it in the hole.
| This usually left enough room for the pin and also wicked the
| solder through.
|
| My biggest issue with DIY boards is drilling the holes and in
| particular getting the bit in the center of the pad. This is such
| a pain, I now just use pre-drilled protoboards and hookup wire on
| one-off or prototypes.
| uuidgen wrote:
| You can make a CNC router pretty easily with an arduino, cnc
| shield and either furniture boards or aluminium profiles.
|
| You you can also make a simple probe for autoleveling and mill
| the pcb too, but imo it takes too much time. Etching has way
| better quality too.
| VLM wrote:
| WRT drilling problems the industry standard solution is make a
| little hole in the PCB layout so there's a ring of copper and
| use the stiffest sharpest carbide bits you can get but realize
| you can't hand old carbide the slightest side force will crack
| the bit, need to milling machine it.
|
| WRT vias there is a circular problem going on with thermal
| vias. If you're building a shipping product with qty 10K+ and
| running into tight financial and thermal constraints the only
| way out sometimes is a field of vias perfectly flat with the
| silicon soldered to it and the vias dump the heat, neither air
| or PCB laminate are good enough thermal conductors.
|
| So if you're building at home and want to pretend to be
| extremely constrained then you can manually perform the mass
| production steps necessary to use vias as heatsinks.
|
| However the more rational less circular way to solve the heat
| problem for onesie-twosie construction projects at home is to
| think outside the box and bit and throw money at the problem.
| You can't afford a 50 cent heatsink on some consumer products
| but I certainly can afford fifty cents in some one-off thing
| I'm bodging together on my workbench at home. Or say you need
| squeaky clean power for a low level analog project, well,
| instead of crazy PCB tricks to dump all the heat in one 7805,
| dump some of the heat in a switcher running at 9 or so volts
| and have the linear reg turn noisy 8 V into clean 5V. The
| "CMRR" equivalent datasheet value for a boring old linear from
| the 70s is like 80 to 100 dB from memory so it'll be clean
| enough for analog work. If you try adding a $2.50 switcher to
| the BoM at work on a qty 100K project "to get out of needing
| thermal vias" your boss will have a quarter million dollar
| heart attack, but at home on a qty 1 project that $2.50 is like
| a rounding error and I just don't care. Or bodge in a beast of
| a heatsink if you need silence. Or bodge in a fan if you can
| afford the acoustic and possible electrical noise.
|
| Now if you're trying to "Work at Home" and do a prototype, just
| while at home, then you have to work as if you're at work.
|
| There are some nifty microwave ICs that as usual turn 99% of
| their input power into heat and they might "Need" to push all
| their heat thru a little grounded field of vias. Even that can
| be bodged using a milling machine and lathe if you make a
| roundish hole and plug it with a solid slug of copper. Remember
| labor cost at home for hobby projects is $0/hr, so something
| that would add ten minutes manual labor to a million product
| production run is perfectly acceptable at home but unthinkable
| at work if you can just use vias.
| fest wrote:
| One thing to watch out for: you're correct on jellybean
| linear regulators having a PSRR of ~80dB, it is frequency
| dependent. It is usually good _at low frequencies_ (couple
| kHz) bu usually falls off as you approach switching
| frequencies of modern DC-DC solutions (a couple hundred kHz
| to couple MHz). It is not uncommon to see PSRR of ~20-30dB at
| 1MHz (e.g. datasheet of L7805 doesn 't even show PSRR beyond
| 100kHz, LM317 is around 20dB at 1MHz).
|
| There are linear regulators that are better in this regard
| though (LT3042 is my favourite for high PSRR).
| jacquesm wrote:
| It's a limitation because this only works for the back and the
| front layer. You can not reliably connect to layers in between
| like this and you can not do 'blind' vias (vias between two or
| more layers not being back or front).
| michaelt wrote:
| _> My biggest issue with DIY boards is drilling the holes and
| in particular getting the bit in the center of the pad._
|
| Trick 1: If you align all your holes on a 2.54mm pitch grid
| (which will be easy enough if you're doing a through-hole
| design) you can tape or clamp some spare protoboard on top
| before drilling. That will then act as a jig, getting all your
| holes nicely lined up with one another.
|
| Trick 2: Drill the holes before you mask the board. This is
| particularly easy if you're drawing out the board by hand, with
| etch-resist pen.
| lmilcin wrote:
| >> My biggest issue with DIY boards is drilling the holes and
| in particular getting the bit in the center of the pad.
|
| Get a small drilling stand that can let you mount the PCB in a
| vise.
|
| Now, I would still use pre-drilled prototyping board. Drilling
| all those holes is just such a hassle. I want to focus on
| designing circuits and boards, not drilling them.
|
| I drill rarely, when the component must be mounted directly to
| the prototyping board but does not conform to standard 2.54mm
| pitch or will not fit the premade holes.
| analog31 wrote:
| Back when I made my own boards, I used a modified pad shape
| (okay, I wrote my own layout program) with a tiny little hole
| in the middle, and after developing the board, the hole
| provided just enough of a dimple to guide the drill.
|
| I made my last homemade board, some kind of electronic music
| circuit, in 1993. Today, there are so many interesting chips
| that are sold as breakout boards by Adafruit, Sparkfun, and the
| like, that it's easy to prototype by just stringing wires
| between boards. For the next level -- has to be nice but not
| commercial and not on my own nickel -- ExpressPCB is my friend.
| stephen_g wrote:
| Yeah, getting good quality circuit boards is so cheap and fast
| now that it's just not worth doing DIY ones in my opinion.
| Protoboard is good for one offs, but beyond that, having four
| layers so massively simplifies routing for anything moderately
| complicated, and you get proper solder mask, proper hole/via
| plating, proper coating (HASL, ENIG etc.)...
|
| Not that a lot of that can't be done DIY, but to do really good
| quality boards at home you start to spend a lot more time
| refining manufacturing processes than actually doing
| electronics! That's fine if that's your jam, it's a valid
| hobby, but I'm much more interested in making more interesting
| projects!
| uuidgen wrote:
| Ordering from china is inexpensive but it takes time. I can
| send a pdf to a local printing house in the evening, get the
| negatives around the noon while the PCB is drilled. Then etch
| and mask it in about 2 hours and solder all the vias in next
| 3 or 4. (I wasn't able to get reliable plating.) Overall one
| day to have a prototype ready.
| leoedin wrote:
| If you pay for fast delivery, a Chinese board can be in
| your hands within a week of ordering. Sure, it's not
| instant, but you can do something else in the mean time.
| syedkarim wrote:
| Where are you getting this kind of turnaround? Is this in
| the US? I purchase a couple dozen protoboards a year and am
| constantly looking for US board houses, but they all have
| lot charges of at least $500 and take a couple days just to
| get a quote back.
| HeyLaughingBoy wrote:
| I use OSHPark for prototyping. I don't know where they
| send the boards, but they hit a reasonable compromise
| between cheap & fast: $5/sq inch for 3 boards. The
| quoting is immediate on their website. I usually have
| boards back in a week after ordering from OSH Park.
|
| For production quantities, I use JLCPcb (China) with
| Airborne for shipping (so it doesn't take a month to get
| here). Their quality is very good. Pay the extra $20 and
| get a stencil to make paste application easy. It's worth
| it. I think my last order of 50 board roughly 2.5x3.5"
| with a metal stencil came to about $70 total with an
| additional $30 for 3-5 day shipping via Airborne.
| madengr wrote:
| Unless you want RF materials, or something other than
| G10/FR4. The cheap prices of aggregating everyone's boards
| comes with the lowest common denominator of material.
|
| Even the 4 layer board processes are not set up for good
| power integrity. They have a center core for layers 2 and 3,
| with 1 and 4 as foils. It ought to be two cores with prepreg
| between, giving the low impedance for internal power planes.
| VLM wrote:
| I remember a W1GHZ project from the 00s or maybe even the
| 90s where he eventually got hairpin filters for low
| microwave frequencies to work using cheap PCBs.
|
| Generic fiberglass is NOT consistent across multiple mfgrs
| enough that you can spec it for mass production from any
| mfgr in any country at any time, you need the very low
| variation specified "RF PCB material" to mass produce
| precision untuned hairpin microwave filters.
|
| HOWEVER, the cool part of the project was generic
| fiberglass is consistent enough across one mfgr over a
| short period of time, that you can characterize product X
| shipped from PCB house Y and then you can very consistently
| get boards at the proper resonant frequencies.
|
| The meme was not overly successful in the amateur radio
| microwave community, sadly, but the project did work
| perfectly well at the time.
| madengr wrote:
| Isola 370 has good consistency, but I'd still only do
| resonant structures on Rogers laminates. The RO4000
| laminates are low cost and work great, but you are paying
| full panel prices when ordering even the smallest PCB.
| Even if it were made in China, I'd never trust them due
| to counterfeit materials.
| aidenn0 wrote:
| > My biggest issue with DIY boards is drilling the holes and in
| particular getting the bit in the center of the pad. This is
| such a pain, I now just use pre-drilled protoboards and hookup
| wire on one-off or prototypes.
|
| I haven't done it with PCB, but for wood when I need a precise
| location and have no drill press, I use a nail to make an
| indentation and use my smallest drill bit to drill it through,
| then I can use progressively larger bits, as they will tend to
| self-center in the hole.
| barbacoa wrote:
| https://www.uyemura.com/pcb-finishes/electroless-copper.html
|
| If you're wanting to do platted through holes idk why you don't
| just use the same elecroless plating chemical that board shops
| use. You could call them and ask for samples and would get enough
| for all your hobby projects.
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