Author Topic: Why are castellations so expensive and are they really what i think they are?  (Read 11486 times)

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Offline RefrigeratorTopic starter

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Your dremel isn't CNC controlled, and I suspect you have no attached vacuum head to suck up the nasty glass dust.
thinking about it, maybe you are right and i was not really know what i was talking about, so i pull out my cutting setup with some unused prototype pcb to do diy castellation test for some minutes (i've never done this since no requirement so far, so this can be my learning process), the pictures worth 1000 words (different person will translate to different words). from before cutting, before burr and then deburr with small diy file,brush to clean off dusts and tweezer to peel off residuals. imho, its doable, up until how many boards you are willing to do this. if you concern about safety hazard, then i guess $4 per board service from fab house is worth it. i just use a 5V USB fan to blow off fiber glass dust, or just let the natural air bring them to surrounding ground. although i have and can mod my vaccum cleaner to do the task if i'm really concern. use mask if you require it, there are quality pricey one, and we have $1 covid mask one sold everywhere today, ymmv.
Is that a regular black/composite cutting disc?
I jumped on ebay and ordered some diamond cutting discs, i don't expect them to arrive anytime soon but when they do they'll be nice to have.

I wonder would it be worth it to prefill the vias with solder to avoid tearout?
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Online Mechatrommer

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Is that a regular black/composite cutting disc?
I jumped on ebay and ordered some diamond cutting discs, i don't expect them to arrive anytime soon but when they do they'll be nice to have.
its brownish or reddish. this thing is really fragile on hand or if you accidentally hit it with your finger while its on the shaft holder. i keep breaking them (not while cutting). so i bought 1 pack original dremel disc 36 pieces like this as long as you handle them like ESD sensitive RF component, they should be alright at cutting many pcb until they run small in diameter. i tried steel disc with sawtooth, that was a big no no, the teeth can stucked on pcb throwing it away, that can be dangerous. i havent tried diamond (steel like) disc. the black (fiberglass reinforced) disc, i have the stock but never tried it i suspect it will run poorer, i think the brownish disc is superb enough at cutting material like pcb laminate. the key here is the sliding table, try cutting with hand will be a PITA, not to mention countless disc you are going to break. ymmv.

I wonder would it be worth it to prefill the vias with solder to avoid tearout?
can be a good idea too but i havent tried, imho higher speed disc rotation and slowly cutting thin layers in few passes may do the trick. looking at the zoomed picture earlier, the holes plating already covered with solder from factory, so i guess its hard enough from tear out while being cut.
« Last Edit: November 24, 2020, 12:32:28 pm by Mechatrommer »
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Offline asmi

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OMG all that trouble to save $30... Your time must be really worthless to do something like that.

Online Mechatrommer

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huh? that only took minutes, including taking pictures, photoshopping and present them to you. you havent to the thread where people are swearing on diy pcb from scratch, dealing with smelly chemicals, drilling and stitching vias and all just to save $30-50 shipping cost of a 5pcs $2 factory made pcbs, this is just one straight cut and a little bit filing. and i have other uses for that cutter too (hint: try to send few like 3-6 designs of very small pcbs to fab house) furthermore if you are going to have like 10-100 orders in the year, thats not a $30 saving. thats between owning a yacht and not owning a yacht.
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Online mikeselectricstuff

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I did some test castellated pads on an AllPCB order recently - they queried  it with 3 options, one of which was basically "try routing it as normal and I don't care what happens" . Worked OK but there were bits of torn plating left
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Offline asmi

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huh? that only took minutes, including taking pictures, photoshopping and present them to you. you havent to the thread where people are swearing on diy pcb from scratch, dealing with smelly chemicals, drilling and stitching vias and all just to save $30-50 shipping cost of a 5pcs $2 factory made pcbs, this is just one straight cut and a little bit filing. and i have other uses for that cutter too (hint: try to send few like 3-6 designs of very small pcbs to fab house) furthermore if you are going to have like 10-100 orders in the year, thats not a $30 saving. thats between owning a yacht and not owning a yacht.
That yacht of yours is gotta be super-cheap one and look more like a canoe. Hint - if you mass-produce PCBs, additional cost for castellations (or just about anything else for that matter) is going to be close to zero. Nobody in their right mind just goes into the website and orders 1M batch of PCBs.

Offline RefrigeratorTopic starter

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I did some test castellated pads on an AllPCB order recently - they queried  it with 3 options, one of which was basically "try routing it as normal and I don't care what happens" . Worked OK but there were bits of torn plating left (Attachment Link) (Attachment Link)
In the first picture the bottom row of pads looks alot cleaner, did you clean them up or are they as-is?
Could the direction of milling also be a big contributor to tearout?
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Offline thm_w

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thinking about it, maybe you are right and i was not really know what i was talking about, so i pull out my cutting setup with some unused prototype pcb to do diy castellation test for some minutes (i've never done this since no requirement so far, so this can be my learning process), the pictures worth 1000 words (different person will translate to different words). from before cutting, before burr and then deburr with small diy file,brush to clean off dusts and tweezer to peel off residuals. imho, its doable, up until how many boards you are willing to do this. if you concern about safety hazard, then i guess $4 per board service from fab house is worth it. i just use a 5V USB fan to blow off fiber glass dust, or just let the natural air bring them to surrounding ground. although i have and can mod my vaccum cleaner to do the task if i'm really concern. use mask if you require it, there are quality pricey one, and we have $1 covid mask one sold everywhere today, ymmv.

Please wear a mask and maybe use a vacuum with HEPA filter or similar, don't blow the dust with a fan. If you need a few dollars I can send it.
Interesting setup though.
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Online mikeselectricstuff

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I did some test castellated pads on an AllPCB order recently - they queried  it with 3 options, one of which was basically "try routing it as normal and I don't care what happens" . Worked OK but there were bits of torn plating left (Attachment Link) (Attachment Link)
In the first picture the bottom row of pads looks alot cleaner, did you clean them up or are they as-is?
Could the direction of milling also be a big contributor to tearout?
If you look carefully the bottom row all have folded-back plating tear-outs, just a bit more consistent.
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Offline GerardG

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Castelation on the bigger holes can be the routing  through plated holes. This can go well on a double sided board.
When using a multilayer it is easy to crack the connection to the innerlayer.

One of the options to make good and clean castellated holes will need to include another routing step between Chemical plating and panel plating.

1. cut panel from CCL
2. Drill plating holes.
3. Chemical copper in all the holes ans slots.
4. Make NPTH slot along the plated holes.
5. Panel plating. slots without chem. copper will not be plated.
etc etc

When your production company is making castellated holes in bulk , it will cost you a percentage on the board price, that is why modules like ESP can be produced cheap.

When you want this in a prototype production it means that the complete production panel must be taken out of the production, do the extra work, put it back into the production flow.
The cheap board manufacturers need to ask some extra for it because of possible damage to the whole production panels (for example 610mmx510mm).

I hope this will clarify some of your questions.

Offline Psi

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I've noticed this issue too.
JLCPCB are quite expensive for castellation hole if you need it on all 4 sides.

Last time I needed a board with 4 side castellation holes it was 50% cheaper from PCBWay vs JLCPCB.
PCBway have a tickbox for castellation holes, but with PCBway there's no extra cost for each additional PCB side with them.

I'd hate to see what JLCPCB charge for a circular PCB with unlimited number of sides  :-DD

If you plan to half-cut them yourself I would recommend using some sort of disk/belt sander/grinder.
I think you will get smoother & cleaner results than trying to use a dermal or a cutting disk.
But make sure you wear a mask to avoid the dust and safety goggles.
« Last Edit: November 25, 2020, 09:53:36 am by Psi »
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Offline RefrigeratorTopic starter

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I'd hate to see what JLCPCB charge for a circular PCB with unlimited number of sides  :-DD
You could argue that there's only one (continuous) side  ;)
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Online Mechatrommer

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numerically speaking, it should converge to $40...
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline Psi

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I'd hate to see what JLCPCB charge for a circular PCB with unlimited number of sides  :-DD
You could argue that there's only one (continuous) side  ;)

They could argue that the step resolution of their XY depanelisation router makes it have like 500 sides :)
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Offline RefrigeratorTopic starter

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Received my boards today and they look super nice.  ;D
But what is that i see? A mistake?  :o
Yep.  :-[
I forgot to break out the RST pin on my micro, but it's programmed through SWD so is RST really necessary?  :-//
No big deal i can solder a wire to the pin when i'm programming the MCU if i end up needing the RST pin.  ^-^
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Online Mechatrommer

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Received my boards today and they look super nice.  ;D
nice. is that from pcbway? how much they charge for that panelization? ie comparing how much cost for not panelized vs panelized pcb?
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline RefrigeratorTopic starter

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Received my boards today and they look super nice.  ;D
nice. is that from pcbway? how much they charge for that panelization? ie comparing how much cost for not panelized vs panelized pcb?
That's actually not a panelized board per se. I just stuffed as many of my boards in the 10x10cm space as i could fit and then added routing to make them easier to cut out.
A 6x91 mm board costs close to the same as a 100x100mm board, hence why i jammed so many of them in there to get the most for my money  ;D
The cost was the same as 100x100mm board.

Also i found another oopsie in my design. I made the breakout pins on the side with 2.54mm spacing to solder in a connector but forgot to make the holes large enough for the pins.  :-[
Rookie mistakes.  :)
« Last Edit: November 30, 2020, 01:59:58 pm by Refrigerator »
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Offline thm_w

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I forgot to break out the RST pin on my micro, but it's programmed through SWD so is RST really necessary?  :-//
No big deal i can solder a wire to the pin when i'm programming the MCU if i end up needing the RST pin.  ^-^

If its atsamd or stm32, never needed RST for the initial programming.
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Offline RefrigeratorTopic starter

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Cut my boards with with my angle grinder, no jig just freehand.
Before cutting i prefilled the holes with solder. I think the castellations came out pretty well.
There were some burrs that caused a short but i sorted that out quickly.
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 
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Offline RefrigeratorTopic starter

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Soldered my thing together and it surprised me how stiff it was after i soldered it.
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 

Offline ElectronRob

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Did you consider just having little wire jumpers with epoxy?

My issue with non plated castellations is that over time, even with slight movement the left over pads will lift etc. Often a little uninsulated wire joiner is quite fast to solder and fairly robust.
 

Offline RefrigeratorTopic starter

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Did you consider just having little wire jumpers with epoxy?

My issue with non plated castellations is that over time, even with slight movement the left over pads will lift etc. Often a little uninsulated wire joiner is quite fast to solder and fairly robust.
They're a bit of a fiddle to solder this way but i think wires would be quite a fiddle as well and i wanted the assembly to be rigid and it really is surprisingly rigid.
I've also thought about the vias pulling out so i added some dummy traces to anchor the pins into the board.
By the way none of the pins are left unused on my boards.
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 

Offline ElectronRob

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Great, glad its worked out well for you  :-+
 

Offline AlexanderB

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Sorry for kicking a slightly older topic, but this one turned up pretty high in the google results when I wanted to figure out what the deal was with JLC and the castellated holes.

The answer is here: https://jlcpcb.com/quote/pcbOrderFaq/Castellated%20holes

Quote
1. If "Yes" is checked, the castellated holes will be made with a special process and extra cost will be charged.
2. If "No" is checked, the castellated holes will still be made but with the ordinary process, so the quality is not promised (e.g. defects may highly occur: unplated holes, incomplete plating, hole with copper residues etc.).

So basically, if you pay the steep fee (it was almost $75 today, apparently), they'll give your board special treatment to make it nice.
If you don't, they just send it, and you most likely end up with some remnants of the plated holes, like what Mike got from AllPCB

I did some test castellated pads on an AllPCB order recently - they queried  it with 3 options, one of which was basically "try routing it as normal and I don't care what happens" . Worked OK but there were bits of torn plating left
 

Offline GerardG

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Hello Alexander,

That is exactly what is meant.

No extra fee, mill through the holes and they are castellated (sort off)
No guarantee on the adhesion of the copper.

Use the "routing before plating" method, get the nice clean castellated holes.



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