Diode -- pick and place

[mkr5000]

When I place an SMD diode in my pcb art top layer, (SOD123) and it's rotated 90 degrees --
is the anode on the right or left?
(and obviously the opposite for 270).

I'm asking because I still don't get the silkscreen layer symbol for the part but
maybe there is a standard based on rotation and the screen symbol doesn't matter? Like even if I had a generic 1206 or something there, they would know the anode/cathode based on rotation?

[John Larkin]

On Thu, 1 Apr 2021 17:43:44 -0700 (PDT), mkr5000 <mike...@gmail.com>
wrote:

>When I place an SMD diode in my pcb art top layer, (SOD123) and it's rotated 90 degrees --
>is the anode on the right or left?

Depends on how it started, and your definition of rotation.

>(and obviously the opposite for 270).
>
>I'm asking because I still don't get the silkscreen layer symbol for the part but
>maybe there is a standard based on rotation and the screen symbol doesn't matter? Like even if I had a generic 1206 or something there, they would know the anode/cathode based on rotation?
>

Show us a picture of the silk symbol.

[Edward Rawde]

"mkr5000" <mike...@gmail.com> wrote in message
news:ee29e5f2-b351-4f6f...@googlegroups.com...

> When I place an SMD diode in my pcb art top layer, (SOD123) and it's
> rotated 90 degrees --
> is the anode on the right or left?

It depends on what the manufacturer's data says.
Given a random example of a SOD123 part I'd do this:
https://www.google.com/search?q=bat42w
And find the necessary information on page 3.

[DecadentLinux...@decadence.org]

John Larkin <jlarkin@highland_atwork_technology.com> wrote in
news:pkqc6ghd4onqq58lg...@4ax.com:

Real simple. There are a numbre of 'standards' and they all
generally depend on what the design engineer prefers or what he wants a
technician to see on the finished product.

This is a simple google images search for "Diode silk screen"

<https://tinyurl.com/2wvjfrru>

[DecadentLinux...@decadence.org]

mkr5000 <mike...@gmail.com> wrote in
news:ee29e5f2-b351-4f6f...@googlegroups.com:

Here is one site's take on making sure there is no confusion...

<https://medium.com/tempo-automation/marking-diode-polarity-
a16dd17e5346>

[Rick C]

There is a standard, but it is only marginally respected. For two pin devices they are oriented horizontally with pin 1 on the left or in the case of a diode the cathode on the left. Rotation is positive. So 90 degrees would have the cathode at 12 oclock.

https://www.eeweb.com/how-to-build-a-pcb-diode-polarity-no-its-not-obvious/

Or do what you want, but show a clear indicator on the silkscreen.

https://www.7pcb.com/blog/how-to-indicate-placement-orientation-of-diodes-leds-on-pcbs.php

--

Rick C.

- Get 1,000 miles of free Supercharging
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[jla...@highlandsniptechnology.com]

That's funny. In about half the cases, the diode covers its own
polarity indication!




--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

[DecadentLinux...@decadence.org]

jla...@highlandsniptechnology.com wrote in
news:i71d6ghp0cmpo806g...@4ax.com:

Yeah, I saw that. It is like they don't know what a silk screen is
for.

Look at my follow up to the OP.

That guy did it right.

[Rick C]

It may be useful to see the markings when trying to verify the orientation, but not to the machine operator. They get a bare board and just need to see the markings long enough to get the machine programmed for the placement. I'm surprised they can do this as quickly as they do. They don't typically charge much for the initial setup. I think a board with over a hundred parts cost me $200 for set up and that is probably more for the machine time as it is for the operator's time. I imagine places like JLCPCB can work so cheaply because they either throw out designs they have too many questions about or they just make it without being sure. I saw a PCB they made where the interchange suffered from lack of understanding. The via pads ended up as hexagons because of minimum spacing. I'm not sure it met the design rules for minimum annular ring anymore, but they got the drill hole pretty much dead center anyway.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

[mkr5000]

I'm just going to count on the fact that JLC will actually look at my screen layer where I have ANODE in caps to note polarity before building ?

Does it have to be in P and P comments (note polarity) or will they look?

[Lasse Langwadt Christensen]

they will usually look and ask if in doubt, but I wouldn't rely on it

just look at the preview when you upload and reup load a file with corrected rotations until you get the desired result

[jla...@highlandsniptechnology.com]

On Fri, 2 Apr 2021 07:12:01 -0700 (PDT), mkr5000 <mike...@gmail.com>

The convention is to tag the cathode of diodes, with a dot or bar or +
or something. That's a legacy of selenium rectifiers.

An arrow is OK, but if the part covers it it impedes inspection.

[John Larkin]

On Fri, 02 Apr 2021 08:11:57 -0700, jla...@highlandsniptechnology.com
wrote:

Here's one:

https://www.dropbox.com/s/3wjrixduj10qktw/D12.jpg?raw=1

[Clifford Heath]

On 3/4/21 1:12 am, mkr5000 wrote:
> I'm just going to count on the fact that JLC will actually look at my screen layer where I have ANODE in caps to note polarity before building ?
>
> Does it have to be in P and P comments (note polarity) or will they look?

JLC use the rotation standard that LCSC uses for EasyEDA; all parts are
unrotated when they are "as the come off the reel". Look at the part on
LCSC, and click the "EasyEDA Model" link. Make sure that your footprint
matches the orientation shown, because that's what they use for assembly.

JLC also provide a placement viewer that you can use to detect rotated
parts. In one case, I found that the viewer showed the wrong rotation,
which turned out to be because the JLC viewer got it wrong - but the
EasyEDA drawing and my own rotation matched up.

CH

[Rick C]

What does "P and P" mean???

What's wrong with giving them the proper orientation? Two pin devices are aligned east/west with pin 1 to the west. Pin 1 is also the positive terminal of caps and inductors or the cathode of diodes. Pin 1 is always the pin to be marked. So that would seem to preclude marking the anode of diodes.

http://ohm.bu.edu/~pbohn/__Engineering_Reference/pcb_layout/pcbmatrix/Component%20Zero%20Orientations%20for%20CAD%20Libraries.pdf

There are also documents that will tell you that rotations are clockwise. As a exercise for the student you can research (google) if components on the bottom side are rotated by viewing them from the top or bottom.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

[Jasen Betts]

I think they will look. especially of the refdes is D-something.

PCBway asked me about polarity of some bidirectional TVS diodes
because it wasn't marked in the silk.

Twice.

In the third batch I called out the part numbers in the fabrication
notes something like:
"D1,D2,D3,D4,D5,D6: these parts are not polarised, either direction is acceptable"
I think that worked.

In the next revision I switced to duals in a SOT323 package for other
reasons.

--
Jasen.

[Hul Tytus]

What software are you using to design your pcb?

Hul

[Three Jeeps]

Instead of hijacking this thread, perhaps as the question in a new thread
J

[Klaus Vestergaard Kragelund]

Before they do the assembly they will send you an email, so you can
confirm the polarity of misc components

[mkr5000]

Thanks Klaus.
I've been trying to submit an order for a week. (my first that needs assembly).

The latest?.............

"Attention!
The PCB specs you chose are not available for SMT assembly. To have your PCB assembled, please reset the PCB specs.
"Panel By JLCPCB" option is not supported"

My single size board is 45 x 43 mm.
I put 5pcs for panel quantity. (I thought they wanted panelized boards on assembly? !).
I listed columns 5 and rows 5.
And get the error above.

So then, I made it single boards, made the qty 30pcs and the error went away.
THEN, I made it 50 pcs because THAT is what I want, and the error came back.

"Attention!
The PCB specs you chose are not available for SMT assembly. To have your PCB assembled, please reset the PCB specs."

So I looked at it and see I want .8mm boards on this and it only ALLOWS 30pcs max !
WTF ?
(and it only allows 50pcs on thicker boards).

I don't get their ordering process AT ALL. I may go to PCBWAY which I've always used before but seems I can save a bit using JLC? Not?

[mkr5000]

AND -- on top of everything else, it ejected my CSV pick and place file......

Name,Value,Layer,Pos-X,Pos-Y,Rot,Package
R1,1000,Top,521.80mil,787.50mil,90,0805
R2,1000,Top,521.80mil,881.25mil,90,0805

and it shows it's csv

[mkr5000]

that's rejected.

[DecadentLinux...@decadence.org]

mkr5000 <mike...@gmail.com> wrote in
news:d14ee51a-4e2a-40f6...@googlegroups.com:

> So I looked at it and see I want .8mm boards on this and it only
> ALLOWS 30pcs max ! WTF ?
> (and it only allows 50pcs on thicker boards).
>
> I don't get their ordering process AT ALL. I may go to PCBWAY
> which I've always used before but seems I can save a bit using
> JLC? Not?
>

Order two 30 pc sets. Or a twenty and a thirty. Problem solved and
you get ten to futz with characterizations and refinements.

[mkr5000]

Ok. Well that leaves my csv file which doesn't pass for some reason. It's definitely a csv file and as shown above.
Their sample file shows DESIGNATOR -- X -- Y -- LAYER -- ROTATION

Does it have to be in that order? Mine also shows part value.

[Jasen Betts]

probably the letters in the numerical columns

--
Jasen.

[mkr5000]

Jasen, I don't follow. ?

[mkr5000]

On Sunday, April 4, 2021 at 5:00:53 PM UTC-4, Jasen Betts wrote:

How should each column be formatted? I'm not clear on that.

[Jasen Betts]

On 2021-04-04, mkr5000 <mike...@gmail.com> wrote:
> On Sunday, April 4, 2021 at 5:00:53 PM UTC-4, Jasen Betts wrote:
>> On 2021-04-04, mkr5000 <mike...@gmail.com> wrote:
>> > On Sunday, April 4, 2021 at 1:46:11 PM UTC-4, mkr5000 wrote:
>> >>
>> >> Name,Value,Layer,Pos-X,Pos-Y,Rot,Package
>> >> R1,1000,Top,521.80mil,787.50mil,90,0805
>> >> R2,1000,Top,521.80mil,881.25mil,90,0805
>> >>
>> >> and it shows it's csv
>> > that's rejected.
>> probably the letters in the numerical columns
>>
>> --
>> Jasen.
> Jasen, I don't follow. ?

Try "521.80" instead of "521.80mil"



--
Jasen.

[DecadentLinux...@decadence.org]

mkr5000 <mike...@gmail.com> wrote in
news:c8c6ad84-d275-4b4c...@googlegroups.com:

Many PCB fab houses only need the PCB layout itself and they will
panelize it for you.

[DecadentLinux...@decadence.org]

mkr5000 <mike...@gmail.com> wrote in news:d9158959-84da-4909-b47b-
8fc086...@googlegroups.com:

Put it in a spreadsheet and then output a CSV from that and examine
the formatting and structure and proofread it for errors. Leading
spaces and trailing spaces in a "field" or "cell" can cause problems.
Sometimes with the output filter itself.

[DecadentLinux...@decadence.org]

Jasen Betts <use...@revmaps.no-ip.org> wrote in news:s4die5$npe$1
@gonzo.revmaps.no-ip.org:

Yes... a numerical column should only have numerics in it.
Put the UOM (Units of Measure) at the top of the column or use a legend
to define the columns.

[mkr5000]

Reply from JLCPB --

"Hi there,
Thank you for your email.
After checked that the format is not like the one of our sample file .
So our system can not detect it easily .
Hope you can understand it .

Attached is the CPL sample file for your reference.
Would you like to take a look and follow our sample file to make your CPL file??
in this way,our system can detect your file successfully.
Thank you ."

Haven't tried it yet but it has to be EXACTLY like their sample file?
Designator X Y Layer Rotation

it has just those 5 in that order.
this whole process is crazy.

I guess you have to adjust the cpl file for each pcb house? !
You would think the software could see the file (like mine above) and modify it.

[Rick C]

What is crazy about them specifying the file format and you not following it??? Oh, I know... the part about you not following it!!

What is wrong with just giving them what they ask for???

YES, you have to provide what each fab house wants. If you go with a US fab house that charges twice as much they will probably work with what you give them. That's one of the reasons they charge more. To provide rock bottom prices the cheap places have to automate the design input and you have to accommodate them.

This is all simple and obvious if you give it a bit of thought.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

[mkr5000]

Well, live and learn right? This is my first assy order. I was dreading having to rewrite the file(s) that my software outputs. I could write some python code that would easily reconfigure the file for what they want you would think they may have dome that themselves. I mean what does it take to identify "R1" and "X" or "Y" etc.?

Just sort of assumed it would be a smoother process without bumps in the road.

[Lasse Langwadt Christensen]

you made all the bumps yourself by trying to take a shortcut instead following directions...

[mkr5000]

well -- did it exactly like they want and it still fails. waiting to hear from them.
did it in Libre Calc, saved it as csv and zilch.

actually, in their directions, they call their CPL sample just that -- "a sample" -- maybe they should be emphatic say do it EXACTLY like this?

maybe it's because I'm using mils? but then they state mm is "preferred" -- they don't say that mil can't be used. maybe in chinese preferred means something else.

[Rick C]

This is not about Python code. Import to a spreadsheet and move the columns around. I'm not clear on the text you added in your net list, but that probably should not be there.

Give the assembly house just what they ask for, nothing more, nothing less.

Why can't you output in mm? See above.

If you do exactly what they say and it still doesn't work, send them the file and ask what's wrong. Maybe they need feedback on a problem with their instructions.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

[DecadentLinux...@decadence.org]

Rick C <gnuarm.del...@gmail.com> wrote in
news:ffc31887-089f-4045...@googlegroups.com:

+1

[DecadentLinux...@decadence.org]

mkr5000 <mike...@gmail.com> wrote in
news:c8557e23-95c8-4278...@googlegroups.com:

Life is one big, long, bumpy road. That's why I ride motocross!

Try HillClimbRacing2 on your iPad

[mkr5000]

message from jlc --
Hi sir or madam,

Oh i see.

Would you mind to send your gerber file and BOM file so that i can try to upload in our website ?? (no issues there)

Also,would you mind to generate your coordinate with mm ??

In this way,our system can recognize it easily .

Thank you .

In Chinese, that probably means we NEED mm but of course, they don't say that.
My senior citizen brain likes mil.

[jla...@highlandsniptechnology.com]

On Tue, 6 Apr 2021 08:20:09 -0700 (PDT), mkr5000 <mike...@gmail.com>
wrote:

We had one Taiwanese company do us a custom extrusion, cut to length
and anodized and tapped. They can't do a 4-40 tap! So we do that part
ourselves.



--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

[DecadentLinux...@decadence.org]

jla...@highlandsniptechnology.com wrote in
news:nc0p6gtbikle25vuf...@4ax.com:

No way! It is so common in the industry! You could have SEMS
inserts pressed in (or is it PEMS?).

[mkr5000]

I've given up on this bullshit.
Got my csv file to go through and the very first board has just 2 resistors and a 2 channel optocoupler on it.
It shows "unselected" parts so I gather it has to be something specific in their library.

Searched LTV-826S (which is what I want and common). No results.
So then, searched "optocouplers" and it comes back with 1800 results including LED's and other crap and no apparent search result filters.

I'll try pcbway and see if it's any different. This JLC is a pain in the ass.

[Lasse Langwadt Christensen]

you expect to get the engineering hours needed to guess what your file format is and what parts you might want for $7 ??

you make the files exactly as specified, and have LCSC part numbers in the BOM, done ..

[Rick C]

Lol. Get used it mm pal. The US isn't dominating industry any more, if they ever did. It's getting hard to find things measured purely in the archaic system. The US Navy still uses yards and will for a long time. Otherwise most of the government is metric. We are just following that lead in the rest of the US, just very slowly as the oldsters die off. It won't be much longer until the US finally just gives it up.

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

[Rick C]

On Tuesday, April 6, 2021 at 3:25:37 PM UTC-4, mkr5000 wrote:
> I've given up on this bullshit.
> Got my csv file to go through and the very first board has just 2 resistors and a 2 channel optocoupler on it.
> It shows "unselected" parts so I gather it has to be something specific in their library.
>
> Searched LTV-826S (which is what I want and common). No results.
> So then, searched "optocouplers" and it comes back with 1800 results including LED's and other crap and no apparent search result filters.
>
> I'll try pcbway and see if it's any different. This JLC is a pain in the ass.

Lol. You give up too quickly. There are third party sites that let you search. I don't recall the urls, but you can use Google to find them. That's what I do. With the third party sites it works well, not Digikey well, but well.

--

Rick C.

--- Get 1,000 miles of free Supercharging
--- Tesla referral code - https://ts.la/richard11209

[Klaus Kragelund]

02.04.21 17:11, jla...@highlandsniptechnology.com wrote:
>On Fri, 2 Apr 2021 07:12:01 -0700 (PDT), mkr5000 <mike...@gmail.com>
>wrote:
>

>>On Friday, April 2, 2021 at 12:39:55 AM UTC-4, gnuarm.del...@gmail.com wrote:

>>> On Thursday, April 1, 2021 at 11:13:27 PM UTC-4, DecadentLinux...@decadence.org wrote:
>>> > jla...@highlandsniptechnology.com wrote in

>>> > news:i71d6ghp0cmpo806g...@4ax.com:
>>> > > On Fri, 2 Apr 2021 01:30:27 +0000 (UTC),
>>> > > DecadentLinux...@decadence.org wrote:
>>> > >
>>> > >>John Larkin <jlarkin@highland_atwork_technology.com> wrote in
>>> > >>news:pkqc6ghd4onqq58lg...@4ax.com:
>>> > >>

>The convention is to tag the cathode of diodes, with a dot or bar or +
>or something. That's a legacy of selenium rectifiers.
>
>An arrow is OK, but if the part covers it it impedes inspection.
>
>
I have not seen a + sign on the Cathode

JLCPCB uses + for Anode and - for cathode

https://support.jlcpcb.com/article/99-does-the-red-dot-means-pin-1-in-the-placement-previewer


--
Klaus Kragelund

[jla...@highlandsniptechnology.com]

That's been standard since selenium rectifiers at least. We use a bar
or a dot on the cathode, like the parts do.

https://www.dropbox.com/s/3wjrixduj10qktw/D12.jpg?raw=1

>
>JLCPCB uses + for Anode and - for cathode
>
>https://support.jlcpcb.com/article/99-does-the-red-dot-means-pin-1-in-the-placement-previewer

Looks like many opportunities for confusion.

I guess that want to shoot parts off their feeders without reviewing
each design. Make the users adapt.

We do our own pick-and-place and somehow never get parts rotated
wrong. I don't know how we manage that; I'll check. I know that
optical inspection is a crosscheck, and we have polarity indications
on the silk to help that.

[mkr5000]

I've got it under control now. I know you're right about mm -- etc. This particular process was excruciating for a first timer. And now I know what no one has put in writing --

(1) Decide on your parts FIRST and get accurate part #'s for BOM and try to use "basic" parts. (I used a lot of popular digi key part numbers and none of them were available).
LCSC? Who knew? Learning about that is too far "down the road".
(2) Use mm (and say it after x and y) for the CPL file and format each column as text (nothing out there that really says "how" to write a cpl file in detail).
(3) then go through their ordering process which could use a touch of user friendly refinement.
(4) done

Seems after I do anything in figuring out a process, I want to do a 2 minute youtube about "here's what you really need to know".

My major problem was my Sprint software doesn't spit out a good to go CPL file.

[Klaus Vestergaard Kragelund]

Actually didn't you complain that the PnP file did not work since you
needed to add "mm"?

I have ordered from them 5 times now. It works if you follow their
instructions and the sample files they provide. So it's really not
difficult. If you have a problem, they have 24/7 support, and they are
very helpful. Much better service than I have ever had with Western PCB
houses

> did it in Libre Calc, saved it as csv and zilch.
>
> actually, in their directions, they call their CPL sample just that -- "a sample" -- maybe they should be emphatic say do it EXACTLY like this?
>

How can you be confused about this. They use the file for a machine, if
you do not format it correctly, they would need to manually correct and
guess what you are trying to do

> maybe it's because I'm using mils? but then they state mm is "preferred" -- they don't say that mil can't be used. maybe in chinese preferred means something else.
>

"mm" is stated in the sample file. Follow that file and you will have no
problems

[mkr5000]

Oh, and by the way, here's a sample of the pcbway centroid file --
https://www.pcbway.com/img/images/pcbway/a-sample-of-PCBWay-Centroid-File.txt

and here's the jlcpcb sample --
https://support.jlcpcb.com/article/79-pick-place-file-for-smt-assembly

so no, there's no room for confusion in this process.