Godamned 0603...

S

Sylvia Else

Guest
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

If I\'d printed out the PCB layout at 1:1 scale, I might have realised
that the pads were absurdly small, but of course, I didn\'t.

Sylvia.
 
On Friday, February 18, 2022 at 6:01:25 AM UTC-5, Jeroen Belleman wrote:
On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial

Designed to confuse. Why do people do that?
Click to expand...

You mean why do people use the measuring system that everyone else in their country use? I guess this is a more pointed question at the US community. I remember working with a mechanical engineer at a military contractor and was surprised they still did everything using inches. 90% of electronic components are in mm as the primary unit. I guess I expect the mechanical community would have converted by now, but, no.

I seem to recall an imperial 0603 is a metric 1608. The places where I would be selecting a part they make it clear which size they are using. On layout I would notice the difference in size, 2.5 to 1. I\'m a bit surprised this error was made. If the layout was done by someone else, maybe not so much. I like doing layouts. It\'s like puzzle solving.

I don\'t get why mil are still used in PCB layout so much. Layer thickness is still done in mil. Trace/space is still commonly in mil. I typically do my layout in mm. 6 mil is 0.1524 mm, so that gets rounded to 0.15 mm. Unfortunately that can trigger the alarms at PCB house pricing software and put you in a higher price category. I remember seeing feature checking software that would sound the alarm at what I can only assume was round off error missing the target by 0.00001 inches or something. I don\'t think I ever used that PWB supplier. I can\'t imagine what it would take to get that through their system. There were dozens if not hundreds of such error reports.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
 
fredag den 18. februar 2022 kl. 15.45.50 UTC+1 skrev gnuarm.del...@gmail.com:
On Friday, February 18, 2022 at 6:01:25 AM UTC-5, Jeroen Belleman wrote:
On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial

Designed to confuse. Why do people do that?
You mean why do people use the measuring system that everyone else in their country use? I guess this is a more pointed question at the US community.. I remember working with a mechanical engineer at a military contractor and was surprised they still did everything using inches. 90% of electronic components are in mm as the primary unit. I guess I expect the mechanical community would have converted by now, but, no.

I seem to recall an imperial 0603 is a metric 1608. The places where I would be selecting a part they make it clear which size they are using. On layout I would notice the difference in size, 2.5 to 1. I\'m a bit surprised this error was made. If the layout was done by someone else, maybe not so much. I like doing layouts. It\'s like puzzle solving.
Click to expand...

https://erp.eso-electronic.com/files/Oi90JOl.png
 
On 18/02/2022 14:45, Rick C wrote:

<snipped>

> I don\'t get why mil are still used in PCB layout so much.

For a thousandth of an inch, we say \'thou\' (with the th as in
thousandth). A mil is often verbal shorthand for a millimetre or
millilitre, depending on context.

That has caused much confusion too.

--
Cheers
Clive
 
On Friday, February 18, 2022 at 9:51:00 AM UTC-5, lang...@fonz.dk wrote:
fredag den 18. februar 2022 kl. 15.45.50 UTC+1 skrev gnuarm.del...@gmail.com:
On Friday, February 18, 2022 at 6:01:25 AM UTC-5, Jeroen Belleman wrote:
On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial

Designed to confuse. Why do people do that?
You mean why do people use the measuring system that everyone else in their country use? I guess this is a more pointed question at the US community. I remember working with a mechanical engineer at a military contractor and was surprised they still did everything using inches. 90% of electronic components are in mm as the primary unit. I guess I expect the mechanical community would have converted by now, but, no.

I seem to recall an imperial 0603 is a metric 1608. The places where I would be selecting a part they make it clear which size they are using. On layout I would notice the difference in size, 2.5 to 1. I\'m a bit surprised this error was made. If the layout was done by someone else, maybe not so much. I like doing layouts. It\'s like puzzle solving.

https://erp.eso-electronic.com/files/Oi90JOl.png
Click to expand...

The power numbers in that chart are not definitive. Different companies rate them differently. I recall one part I was using because it had much higher dissipation in a small package. Then it was discontinued! But others had similar parts by then.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209
 
On 02/18/2022 03:45 PM, Rick C wrote:
On Friday, February 18, 2022 at 6:01:25 AM UTC-5, Jeroen Belleman wrote:
On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial

Designed to confuse. Why do people do that?

You mean why do people use the measuring system that everyone else in their country use? I guess this is a more pointed question at the US community. I remember working with a mechanical engineer at a military contractor and was surprised they still did everything using inches. 90% of electronic components are in mm as the primary unit. I guess I expect the mechanical community would have converted by now, but, no.

I seem to recall an imperial 0603 is a metric 1608. The places where I would be selecting a part they make it clear which size they are using. On layout I would notice the difference in size, 2.5 to 1. I\'m a bit surprised this error was made. If the layout was done by someone else, maybe not so much. I like doing layouts. It\'s like puzzle solving.

I don\'t get why mil are still used in PCB layout so much. Layer thickness is still done in mil. Trace/space is still commonly in mil. I typically do my layout in mm. 6 mil is 0.1524 mm, so that gets rounded to 0.15 mm. Unfortunately that can trigger the alarms at PCB house pricing software and put you in a higher price category. I remember seeing feature checking software that would sound the alarm at what I can only assume was round off error missing the target by 0.00001 inches or something. I don\'t think I ever used that PWB supplier. I can\'t imagine what it would take to get that through their system. There were dozens if not hundreds of such error reports.
Click to expand...
Because it\'s 1 to two digit small integers for all the practical
sizes on a board.
The millimeter/micrometer sizes are all off by at least a factor of ten
to be convenient.

metric pin headers/screw clamps are also sh!t
it works to have 2 pins 5.00mm in 5.08(2x100mil) holes.
but when it\'s 8 pins long or so it won\'t fit anymore.
(perfboards!)
 
On Friday, February 18, 2022 at 10:26:18 AM UTC-5, Johann Klammer wrote:
On 02/18/2022 03:45 PM, Rick C wrote:
On Friday, February 18, 2022 at 6:01:25 AM UTC-5, Jeroen Belleman wrote:
On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial

Designed to confuse. Why do people do that?

You mean why do people use the measuring system that everyone else in their country use? I guess this is a more pointed question at the US community. I remember working with a mechanical engineer at a military contractor and was surprised they still did everything using inches. 90% of electronic components are in mm as the primary unit. I guess I expect the mechanical community would have converted by now, but, no.

I seem to recall an imperial 0603 is a metric 1608. The places where I would be selecting a part they make it clear which size they are using. On layout I would notice the difference in size, 2.5 to 1. I\'m a bit surprised this error was made. If the layout was done by someone else, maybe not so much. I like doing layouts. It\'s like puzzle solving.

I don\'t get why mil are still used in PCB layout so much. Layer thickness is still done in mil. Trace/space is still commonly in mil. I typically do my layout in mm. 6 mil is 0.1524 mm, so that gets rounded to 0.15 mm. Unfortunately that can trigger the alarms at PCB house pricing software and put you in a higher price category. I remember seeing feature checking software that would sound the alarm at what I can only assume was round off error missing the target by 0.00001 inches or something. I don\'t think I ever used that PWB supplier. I can\'t imagine what it would take to get that through their system. There were dozens if not hundreds of such error reports.

Because it\'s 1 to two digit small integers for all the practical
sizes on a board.
The millimeter/micrometer sizes are all off by at least a factor of ten
to be convenient.
Click to expand...

Sorry, what is convenient about 250 mil? Or 850 mil, or 4500 mil? I\'m good with 6.35 mm or better just 6 mm for a mounting pad. My board is 21.6 x 114 mm in metric. I don\'t find that cumbersome although I probably would have made it 21.6 mm (required by the application) by 110 mm (selected by me).


metric pin headers/screw clamps are also sh!t
it works to have 2 pins 5.00mm in 5.08(2x100mil) holes.
but when it\'s 8 pins long or so it won\'t fit anymore.
(perfboards!)
Click to expand...

I haven\'t used a perf board in 20 years. I also don\'t typically use through hole, although it does show up for cable connectors for ribbon cables. In that case, 2.5 mm spaced connectors are not an option. I didn\'t know they made them. I\'ve seen 2 mm and 1 mm, but 2.5 mm??? What are these 5.0 mm connectors, more than 8 pins long? I\'m guessing something that might be used in a washing machine sort of appliance?

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209
 
On Fri, 18 Feb 2022 19:31:48 +1100, Sylvia Else <sylvia@email.invalid>
wrote:

I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.
Click to expand...

Your PCB layout program library (or person) must be ambiguous.

0603 appears to be the only size where this trap arises, and I fell
right into it.

If I\'d printed out the PCB layout at 1:1 scale, I might have realised
that the pads were absurdly small, but of course, I didn\'t.

Sylvia.
Click to expand...

Since SMT originated in the USA, at IBM, everyone could have kept the
original size nomenclature. Or at least done something original if
they insisted on going metric, like 06M03 or something. An M8 screw is
clearly distinct from a number 8.

I like to use 0805s. 0603s are getting too small to handle and probe.
I recently used some 0402s for some really fast stuff, and I hate
them. Metric 0602 is 0201 in plain English, spec-of-dust size.

Most passive are made on 20 mil thick alumina, so the small ones tend
towards cubes.

Did you use reference designators? That would have made the size
difference more obvious.



--

I yam what I yam - Popeye
 
On Fri, 18 Feb 2022 12:01:14 +0100, Jeroen Belleman
<jeroen@nospam.please> wrote:

On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial


Designed to confuse. Why do people do that?

Jeroen Belleman
Click to expand...

The early IC designers defined as inch as equal to 25 mm.



--

I yam what I yam - Popeye
 
On Friday, February 18, 2022 at 11:03:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Fri, 18 Feb 2022 19:31:48 +1100, Sylvia Else <syl...@email.invalid
wrote:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.
Your PCB layout program library (or person) must be ambiguous.

0603 appears to be the only size where this trap arises, and I fell
right into it.

If I\'d printed out the PCB layout at 1:1 scale, I might have realised
that the pads were absurdly small, but of course, I didn\'t.

Sylvia.
Since SMT originated in the USA, at IBM, everyone could have kept the
original size nomenclature. Or at least done something original if
they insisted on going metric, like 06M03 or something. An M8 screw is
clearly distinct from a number 8.
Click to expand...

I don\'t see 0603 used as a label for metric sizes. Digikey clearly lists (0603 Metric) as a size. Data sheets seem to use 0603 as a label for 1.6 x 0.8 mm parts. I\'m not finding the confusion issue.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209
 
On 2022-02-18 17:06, jlarkin@highlandsniptechnology.com wrote:
On Fri, 18 Feb 2022 12:01:14 +0100, Jeroen Belleman
jeroen@nospam.please> wrote:

On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial


Designed to confuse. Why do people do that?

Jeroen Belleman

The early IC designers defined as inch as equal to 25 mm.
Click to expand...

The point is not whether we should use metric or inches. The
point is that the /syntax/ of the size designators should be
distinguishable. Without further indications, I would assume
that 0603 is imperial.

Jeroen Belleman
 
fredag den 18. februar 2022 kl. 16.39.34 UTC+1 skrev gnuarm.del...@gmail.com:
On Friday, February 18, 2022 at 10:26:18 AM UTC-5, Johann Klammer wrote:
On 02/18/2022 03:45 PM, Rick C wrote:
On Friday, February 18, 2022 at 6:01:25 AM UTC-5, Jeroen Belleman wrote:
On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial

Designed to confuse. Why do people do that?

You mean why do people use the measuring system that everyone else in their country use? I guess this is a more pointed question at the US community. I remember working with a mechanical engineer at a military contractor and was surprised they still did everything using inches. 90% of electronic components are in mm as the primary unit. I guess I expect the mechanical community would have converted by now, but, no.

I seem to recall an imperial 0603 is a metric 1608. The places where I would be selecting a part they make it clear which size they are using. On layout I would notice the difference in size, 2.5 to 1. I\'m a bit surprised this error was made. If the layout was done by someone else, maybe not so much. I like doing layouts. It\'s like puzzle solving.

I don\'t get why mil are still used in PCB layout so much. Layer thickness is still done in mil. Trace/space is still commonly in mil. I typically do my layout in mm. 6 mil is 0.1524 mm, so that gets rounded to 0.15 mm. Unfortunately that can trigger the alarms at PCB house pricing software and put you in a higher price category. I remember seeing feature checking software that would sound the alarm at what I can only assume was round off error missing the target by 0.00001 inches or something. I don\'t think I ever used that PWB supplier. I can\'t imagine what it would take to get that through their system. There were dozens if not hundreds of such error reports.

Because it\'s 1 to two digit small integers for all the practical
sizes on a board.
The millimeter/micrometer sizes are all off by at least a factor of ten
to be convenient.
Sorry, what is convenient about 250 mil? Or 850 mil, or 4500 mil? I\'m good with 6.35 mm or better just 6 mm for a mounting pad. My board is 21.6 x 114 mm in metric. I don\'t find that cumbersome although I probably would have made it 21.6 mm (required by the application) by 110 mm (selected by me).
metric pin headers/screw clamps are also sh!t
it works to have 2 pins 5.00mm in 5.08(2x100mil) holes.
but when it\'s 8 pins long or so it won\'t fit anymore.
(perfboards!)
I haven\'t used a perf board in 20 years. I also don\'t typically use through hole, although it does show up for cable connectors for ribbon cables. In that case, 2.5 mm spaced connectors are not an option. I didn\'t know they made them. I\'ve seen 2 mm and 1 mm, but 2.5 mm??? What are these 5.0 mm connectors, more than 8 pins long? I\'m guessing something that might be used in a washing machine sort of appliance?
Click to expand...

the very common JST-XH is 2.50mm, supposedly you can get up 20 pin but I don\'t think I\'ve seen more than 6
 
fredag den 18. februar 2022 kl. 17.06.53 UTC+1 skrev jla...@highlandsniptechnology.com:
On Fri, 18 Feb 2022 12:01:14 +0100, Jeroen Belleman
jer...@nospam.please> wrote:

On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial


Designed to confuse. Why do people do that?

Jeroen Belleman
The early IC designers defined as inch as equal to 25 mm.
Click to expand...

since it is now standardized as 25.4mm, pretty close
 
Am 18.02.22 um 17:02 schrieb jlarkin@highlandsniptechnology.com:

I like to use 0805s. 0603s are getting too small to handle and probe.
I recently used some 0402s for some really fast stuff, and I hate
them. Metric 0602 is 0201 in plain English, spec-of-dust size.
Click to expand...

At a customer\'s, the solder ladies bragged they could solder
everything. I showed them my Murata 01005 starter kit.
Oh what a shock!

Ger \"the bags are all empty\" hard
 
On Friday, February 18, 2022 at 11:49:09 AM UTC-5, Jeroen Belleman wrote:
On 2022-02-18 17:06, jla...@highlandsniptechnology.com wrote:
On Fri, 18 Feb 2022 12:01:14 +0100, Jeroen Belleman
jer...@nospam.please> wrote:

On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial


Designed to confuse. Why do people do that?

Jeroen Belleman

The early IC designers defined as inch as equal to 25 mm.
The point is not whether we should use metric or inches. The
point is that the /syntax/ of the size designators should be
distinguishable. Without further indications, I would assume
that 0603 is imperial.
Click to expand...

I find that passive data sheets all have dimensional data. Even with the same designation without the confusion of metric/imperial, parts vary in size. I select a pad size that is appropriate.


--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209
 
On Fri, 18 Feb 2022 15:02:21 +0000, Clive Arthur
<clive@nowaytoday.co.uk> wrote:

On 18/02/2022 14:45, Rick C wrote:

snipped

I don\'t get why mil are still used in PCB layout so much.

For a thousandth of an inch, we say \'thou\' (with the th as in
thousandth). A mil is often verbal shorthand for a millimetre or
millilitre, depending on context.

That has caused much confusion too.
Click to expand...

Not so fast there. Too Euro-centric?

In the US, traditionally a \"mil\" is 0.001\", and a \"tenth\" is 0.0001\",
and a millimeter is a millimeter (\"mm\") and never a mil.

Joe Gwinn
 
On Friday, February 18, 2022 at 6:45:50 AM UTC-8, gnuarm.del...@gmail.com wrote:
On Friday, February 18, 2022 at 6:01:25 AM UTC-5, Jeroen Belleman wrote:
On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

Designed to confuse. Why do people do that?

You mean why do people use the measuring system that everyone else in their country use? I guess this is a more pointed question at the US community.. I remember working with a mechanical engineer at a military contractor and was surprised they still did everything using inches. 90% of electronic components are in mm as the primary unit. I guess I expect the mechanical community would have converted by now, but, no.
Click to expand...

Pre-NATO, all US military machinery would have been inches; even now,
NATO has standard 7.62 mm ammo, which is just a soft-conversion
from .30 caliber...

Conversion is a slow process. In the print industries, inches have been the norm; in
science, it has been SI (metric) units for decades. So early semiconductor designs
had diffusion depths in microns, and emitter areas in... square micro-inches.
Because the emitters were printed.

Eventually it gets sorted out... but I\'ve got a century-old machine tool
that has inch-standard parts everywhere except one lefthand metric screw...
so don\'t expect the conversion-in-progress phase to be complete in your
lifetime. Digitization, if anything, will impede the progress; your calipers
are made with a \'convert to\' button, so the multiple standards don\'t
bother one so much.
 
fredag den 18. februar 2022 kl. 19.51.04 UTC+1 skrev whit3rd:
On Friday, February 18, 2022 at 6:45:50 AM UTC-8, gnuarm.del...@gmail.com wrote:
On Friday, February 18, 2022 at 6:01:25 AM UTC-5, Jeroen Belleman wrote:
On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.
Designed to confuse. Why do people do that?

You mean why do people use the measuring system that everyone else in their country use? I guess this is a more pointed question at the US community. I remember working with a mechanical engineer at a military contractor and was surprised they still did everything using inches. 90% of electronic components are in mm as the primary unit. I guess I expect the mechanical community would have converted by now, but, no.
Pre-NATO, all US military machinery would have been inches; even now,
NATO has standard 7.62 mm ammo, which is just a soft-conversion
from .30 caliber...

Conversion is a slow process. In the print industries, inches have been the norm; in
science, it has been SI (metric) units for decades. So early semiconductor designs
had diffusion depths in microns, and emitter areas in... square micro-inches.
Because the emitters were printed.

Eventually it gets sorted out... but I\'ve got a century-old machine tool
that has inch-standard parts everywhere except one lefthand metric screw....
so don\'t expect the conversion-in-progress phase to be complete in your
lifetime. Digitization, if anything, will impede the progress; your calipers
are made with a \'convert to\' button, so the multiple standards don\'t
bother one so much.
Click to expand...

or it might help, if all your tools/machines/instruments can only do one standard
switching means throwing it all away. If they can do both like every CNC or digital caliper
switching is just a push of a button
 
jlarkin@highlandsniptechnology.com wrote:
On Fri, 18 Feb 2022 12:01:14 +0100, Jeroen Belleman
jeroen@nospam.please> wrote:

On 2022-02-18 11:11, Lasse Langwadt Christensen wrote:
fredag den 18. februar 2022 kl. 09.32.02 UTC+1 skrev Sylvia Else:
I\'ve got a board made that includes pads for some 0603 smds.

How was I expected to know that 0603 is used for both imperial and
metric sizes? No wonder there\'s no way I can put my imperial 0603
components onto the metric 0603 landing pads.

0603 appears to be the only size where this trap arises, and I fell
right into it.

also 0402 metric which is 01005 imperial


Designed to confuse. Why do people do that?

Jeroen Belleman

The early IC designers defined as inch as equal to 25 mm.
Click to expand...

Wasn\'t that the commies that did that? COMECON semiconductors have that
silly 2.5mm lead spacing in DIP packages -aka \"metric inch\" or something
like that.
 
On Friday, February 18, 2022 at 1:15:55 PM UTC-5, Joe Gwinn wrote:
On Fri, 18 Feb 2022 15:02:21 +0000, Clive Arthur
cl...@nowaytoday.co.uk> wrote:

On 18/02/2022 14:45, Rick C wrote:

snipped

I don\'t get why mil are still used in PCB layout so much.

For a thousandth of an inch, we say \'thou\' (with the th as in
thousandth). A mil is often verbal shorthand for a millimetre or
millilitre, depending on context.

That has caused much confusion too.
Not so fast there. Too Euro-centric?

In the US, traditionally a \"mil\" is 0.001\", and a \"tenth\" is 0.0001\",
and a millimeter is a millimeter (\"mm\") and never a mil.
Click to expand...

Your label of \"Euro-centric\" would seem to be rather US-centric. It\'s pretty much us against the world on this one. I do see some data sheets that seem to treat inches as the obligatory technical concession to the US. Otherwise it is metric all the way.

It\'s a damn good thing they had already developed metric measurements for electricity by the time things got rolling. Otherwise we would be the only country left measuring resistance in barley corns and electrical potential in hands, requiring a conversion factor of 3.92118E-4 to get current flow in ounces of silver per fortnight.

--

Rick C.

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