Are small SMD resistors factory-tested one by one?

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I wonder if the accuracy is granted by the process itself,by testing samples,or automatic test one by one;
the last would be amazing in case of very cheap and very small resistors(or other passive components).The same question could be extended to semiconductors,despite test on wafer is probably easier, by mechanical point of view,what about the sealed component?
Thanks and forgive improper use of english language.
Diego

Re: Are small SMD resistors factory-tested one by one?

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Resistors are generally laser trimmed. Look at some under a
microscope. Trimming requires that every resistor be measured.

We only buy 1% resistors, and they are probably all trimmed.
Apparently some sloppier parts, like 10%, aren't trimmed. Heck, a
resistor that fails one bin can just go into the next one.

But we never see bad resistors. Whatever the process, it sure works.

An automatic test machine could measure resistors as fast as they can
be processed. A millisecond is plenty of time to measure resistance.

Youtube knows all.


https://www.youtube.com/watch?v=wshRwO0MCSU





--  

John Larkin         Highland Technology, Inc

Science teaches us to doubt.

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Re: Are small SMD resistors factory-tested one by one?
On Sunday, September 20, 2020 at 2:02:40 PM UTC-4, jla...@highlandsniptechn
ology.com wrote:
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ples,or automatic test one by one;  
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(or other passive components).The same question could be extended to semico
nductors,despite test on wafer is probably easier, by mechanical point of v
iew,what about the sealed component?  
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   I just got another 700+, 7" reels of resistors, capacitors and transisto
rs. Most appear to be full reels. It is going to take a while to sort every
thing out.

Re: Are small SMD resistors factory-tested one by one?
On Tue, 22 Sep 2020 07:32:48 -0700 (PDT), Michael Terrell

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I, and the rest of my engineers, have been forbidden from taking parts
out of the stock room. We have to send an email, and one of the
production people bring us the parts. I don't like to wait, so we've
bought a lot of various R and C and L sample kits for engineering, and
I have a private stock of ICs and discretes.

And there's always nights and weekends.  

I have a career-long record of successfully burgling stockrooms.




--  

John Larkin         Highland Technology, Inc

Science teaches us to doubt.

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Re: Are small SMD resistors factory-tested one by one?
On Tuesday, September 22, 2020 at 11:07:23 AM UTC-4, John Larkin wrote:
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samples,or automatic test one by one;  
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ors(or other passive components).The same question could be extended to sem
iconductors,despite test on wafer is probably easier, by mechanical point o
f view,what about the sealed component?  
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ors. Most appear to be full reels. It is going to take a while to sort ever
ything out.
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Me, too. The first time was in the Army. They wouldn't give me what I neede
d to keep a TV station on the air. In a three week period, I used 1400 line
 items, at a total of a little over 2100 parts. The station was still in go
od shape almost two years later when it was decommissioned and dismantled.  
I've talked to people who were there after I left for home.

I have a room full of discretes. There were a lot of ROHS COG SMD capacitor
s in the last purchase. Most are under 1000pF. A real boon for people who p
lay with RF. I have a local electroncs store that sells components to the p
ublic that I can trade parts with on a reel by reel basis. I also have doze
ns of 'Taiyo Yuden SMD/SMT Capacitor Kits' in small footprints.


Re: Are small SMD resistors factory-tested one by one?
On Tue, 22 Sep 2020 09:59:34 -0700 (PDT), Michael Terrell

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I never worked for a company so big that I couldn't walk to the
stockroom and production floor and machine shop. I've known engineers
who worked in a "office building" where there they didn't even have a
lab. And I know outfits that send everything, even prototypes, out to
a contract manufacturer.

I could tell a funny story.


Re: Are small SMD resistors factory-tested one by one?
On Tuesday, September 22, 2020 at 3:31:23 PM UTC-4, John Larkin wrote:
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eded to keep a TV station on the air. In a three week period, I used 1400 l
ine items, at a total of a little over 2100 parts. The station was still in
 good shape almost two years later when it was decommissioned and dismantle
d. I've talked to people who were there after I left for home.  
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tors in the last purchase. Most are under 1000pF. A real boon for people wh
o play with RF. I have a local electroncs store that sells components to th
e public that I can trade parts with on a reel by reel basis. I also have d
ozens of 'Taiyo Yuden SMD/SMT Capacitor Kits' in small footprints.
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Tell it.  

I don't have a full machine shop, but I do have some nice tools for buildin
g prototypes. I havee a Cameron precision drill press, a floor model drill  
press and  a small milling machine. My latest addition was a small lathe. T
hey are in my 1200 Sq foot detached  
garage.

Re: Are small SMD resistors factory-tested one by one?
On Tue, 22 Sep 2020 15:25:21 -0700 (PDT), Michael Terrell

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Well, sorta funny. I was chief engineer of a big company. I was 25 and
looked 15. I went into the machine shop and asked a guy to drill a
hole in a piece of aluminum for me. He said "Who do you think you
are?" and I said "I'm Larkin." He was shocked. All the big burly
machinists surrounded me and pointed and said "That's Larkin!"  

He drilled it for me. I wound up dirt bike riding with a bunch of
them. They made their own pistons.


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We have a nice little shop downstairs. My manufacturing manager is a
superb machinist and mechanical designer too. That's really handy to
have around.




--  

John Larkin         Highland Technology, Inc

Science teaches us to doubt.

We've slightly trimmed the long signature. Click to see the full one.
Re: Are small SMD resistors factory-tested one by one?
On Tuesday, September 22, 2020 at 10:46:30 PM UTC-4,John Larkin wrote:  
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e:  
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 needed to keep a TV station on the air. In a three week period, I used 140
0 line items, at a total of a little over 2100 parts. The station was still
 in good shape almost two years later when it was decommissioned and disman
tled. I've talked to people who were there after I left for home.  
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acitors in the last purchase. Most are under 1000pF. A real boon for people
 who play with RF. I have a local electroncs store that sells components to
 the public that I can trade parts with on a reel by reel basis. I also hav
e dozens of 'Taiyo Yuden SMD/SMT Capacitor Kits' in small footprints.  
Quoted text here. Click to load it
  
Quoted text here. Click to load it
  
Quoted text here. Click to load it
  
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ding prototypes. I have a Cameron precision drill press, a floor model dril
l press and a small milling machine. My latest addition was a small lathe.  
They are in my 1200 Sq foot detached  
Quoted text here. Click to load it

I had only worked at Microdyne for a couple weeks when some guy walked up a
nd starts asking me a bunch of questions. He didn't introduce himself, and  
some of the questions were things that no one outside of the company should
 be asking. I looked up from the bench and said, "Excuse me, but I have wor
k to do." He came back five minutes later with my boss who was furious!. Th
e man was the head of production, but he had not been introduced to me. He  
told my boss that I had done the right thing by not just sit there talking  
to a stranger.

I learned to run a lathe in high school, and a friend owned a nice machine  
shop in Ohio. He manufactured replacement parts for Model T and Model A For
ds. Most were made on original Ford dies. He was one of the first companies
 allowed to use the Ford logo on his boxes. He made replica ignition coils  
with he Ford logo embossed on the steel can. He bought the raw coils from E
chlin, and put them in the cans that he stamped. He made the Model T fender
s with a heavy steel wire rolled into the edge, on original tooling and mac
hines from Ford. I could use any machine that wasn't in use. He started thi
s part time, while working as a tool and die maker in the Aerospace industr
y. That company developed the honeycomb steel heat shields for the early sp
ace program. He went full time during a layoff, and never went back.

Re: Are small SMD resistors factory-tested one by one?
On Tue, 22 Sep 2020 23:25:54 -0700 (PDT), Michael Terrell

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I like worker-guys - plumbers, farmers, electricians, machinists,
construction guys with giant pickup trucks.  

At the place I mentioned, we had a huge Whitney n/c punch press. It
would punch 4" holes in 1/8" steel plate about 1 per second, and the
building shook at every hit. It was programmed from paper tape in an
atrocious format, so I wrote a language compiler for our PDP11
timeshare system, loosely based on Quickpoint syntax. It was fairly
basic, but it did have a PATn command to punch a pattern and remember
it for reuse, and OFS Xddddd Yddddd and OFS DXcccccc DYnnnnn to offset
the origin absolutely and incrementally. We turned that loose on the
machinists and discovered that they were soon writing elegant and
efficient programs with just a few control tools.  

I also implemented a BHC (bolt hole circle) command which they adapted
to scallop really big holes using a smaller punch. It was awesome to
watch it punch out their programs on a big steel console panel.

The Westinghouse n/c controller was all discrete-transistor logic
cards. It read a paper tape and could do smooth vector moves into big
servo motors with encoders, using what we'd think of as a DDS
algorithm, all in BCD.

One thing I've noticed about those worker-guys is that they tend to be
mystified by and afraid of electricity. They think I wear robes and
pointy hats because I can wire a ceiling fan.

All kids should learn some basic machining and welding and
electrical/electronics skills. Some really high-end private high
schools do that.



--  

John Larkin         Highland Technology, Inc

Science teaches us to doubt.

We've slightly trimmed the long signature. Click to see the full one.
Re: Are small SMD resistors factory-tested one by one?
On Wednesday, September 23, 2020 at 11:46:30 AM UTC-4, John Larkin wrote:
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:  
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rote:  
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t I needed to keep a TV station on the air. In a three week period, I used  
1400 line items, at a total of a little over 2100 parts. The station was st
ill in good shape almost two years later when it was decommissioned and dis
mantled. I've talked to people who were there after I left for home.  
Quoted text here. Click to load it
capacitors in the last purchase. Most are under 1000pF. A real boon for peo
ple who play with RF. I have a local electroncs store that sells components
 to the public that I can trade parts with on a reel by reel basis. I also  
have dozens of 'Taiyo Yuden SMD/SMT Capacitor Kits' in small footprints.  
Quoted text here. Click to load it
rs  
Quoted text here. Click to load it
 a  
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to  
Quoted text here. Click to load it
  
Quoted text here. Click to load it
uilding prototypes. I have a Cameron precision drill press, a floor model d
rill press and a small milling machine. My latest addition was a small lath
e. They are in my 1200 Sq foot detached  
Quoted text here. Click to load it
  
Quoted text here. Click to load it
  
Quoted text here. Click to load it
p and starts asking me a bunch of questions. He didn't introduce himself, a
nd some of the questions were things that no one outside of the company sho
uld be asking. I looked up from the bench and said, "Excuse me, but I have  
work to do." He came back five minutes later with my boss who was furious!.
 The man was the head of production, but he had not been introduced to me.  
He told my boss that I had done the right thing by not just sit there talki
ng to a stranger.  
Quoted text here. Click to load it
ne shop in Ohio. He manufactured replacement parts for Model T and Model A  
Fords. Most were made on original Ford dies. He was one of the first compan
ies allowed to use the Ford logo on his boxes. He made replica ignition coi
ls with he Ford logo embossed on the steel can. He bought the raw coils fro
m Echlin, and put them in the cans that he stamped. He made the Model T fen
ders with a heavy steel wire rolled into the edge, on original tooling and  
machines from Ford. I could use any machine that wasn't in use. He started  
this part time, while working as a tool and die maker in the Aerospace indu
stry. That company developed the honeycomb steel heat shields for the early
 space program. He went full time during a layoff, and never went back.
Quoted text here. Click to load it

They need to put shop classes back into public schools. It was a huge mista
ke to remove them. I took every shop class that I could, along with the Col
lege prep track that I was on. I got sick of being told that I should go in
to medicine or law, because of my IQ. I also got sick of being told that I  
needed to see the numbers. I never did look at whatever was in the envelop  
that they slid across the table to me. I just pushed it back. I was but on  
thee College Prep track in thee seventh grade. I often got the highest scor
es on the aptitude tests of anyone in my school system, but it didn't matte
r to me. I wanted to learn, for the sake of learning, not to impress people
. I had a good laugh after one test on mechanics. There were two perfect sc
ores in the entire school system. Me and a girl. The boys who claimed to be
 mechanical geniuses scored very low. They couldn't figure out what directi
on the output shaft would turn in a gearbox, yet it was obvious at a glance
.

I learned to weld. I learned to wire a house when I was 10. I have a portab
le Oxyacetylene torch that can be carried to places that you can't take the
 big bottles. Those were handy as a Broadcast Engineer. You could cut up ol
d crap too remove it, or make temporary repairs until a tower crew could re
place a tower. They were also handy to solder 2" and larger copper pipe i t
he transmitter cooling systems. People thought that I was nuts, because I p
re-tinned the pipe and the cast brass fittings, but my work never leaked. O
ld systems that I had to take apart often had only a thin ring of flowed so
lder that would crack from vibration. One idiot had brazed the copper pie t
o the brass fittings. Those took a lot of work to reuse. They were custom d
esigned by RCA, and there hadn't been spares for at least a decade. I had t
o use Oxyacetylene on an area that wasn't brazed, and drive a thin punch in
to the seam to dimlpe the copper pipe. Then I had to file the brazing off f
rom the sloppy repairs. After that, a large pair of needle nose pliers were
 used to twist it loose while the solder was molten. I salvaged and reused  
every one of them. It was the worst use of 50/50 solder that I had ever see
n. I replaced it with a very high tin content solder that flowed properly.  
It had 0.5% Antimony and may have been 99.5% tin. I still have the rest of  
the five pound spool somewhere.

I had a bunch of those large, bright orange Burroughs plasma displays for e
arly CNC machines. They were from industrial terminals wit cast aluminum ca
binets. The displays ran so hot that they needed it to cool the displays. I
 think they were in a warehouse that I lost in 2001 when I  ended up bedrid
den for two years.

Re: Are small SMD resistors factory-tested one by one?
On Wednesday, 23 September 2020 18:51:08 UTC+1, Michael Terrell  wrote:

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I learnt how not to wire a house when I was 10.

Re: Are small SMD resistors factory-tested one by one?
On Wednesday, September 23, 2020 at 7:51:52 PM UTC-4, Tabby wrote:
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Did you burn it down?

Re: Are small SMD resistors factory-tested one by one?
On Thursday, 24 September 2020 14:34:01 UTC+1, Michael Terrell  wrote:
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no :P

Re: Are small SMD resistors factory-tested one by one?
On 2020-09-22 22:46, snipped-for-privacy@highlandsniptechnology.com wrote:
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Probably on company time. ;)

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When our ship comes in, we're going to get a bigger lab with a room
dedicated to mechanical work and test jigs.  We couldn't fit even a
Sherline into our current space because of all the other stuff. ;)

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Are small SMD resistors factory-tested one by one?
On Wed, 23 Sep 2020 17:50:51 -0400, Phil Hobbs

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Several of us had Yamaha 250 dirt bikes. I was used to mine. I tried
one of the machinist's bikes, cranked the throttle as usual, and it
wheelied and flung me into the air. They found that to be amusing.

We'd ride in the bonnet carre spillway (which was illegal) and play
motorcycle tag in a big bowl-shaped gravel pit. Crashed a lot.


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We have a Tormach, which is fabulous. But I still like our ancient
manual Bridgeport; you can *feel* it cutting metal. When they refurbed
it, I wanted them to paint it purple but they stuck with grey.

https://www.dropbox.com/s/8iusfwe1k62w2fr/Tor1.JPG?raw=1




Re: Are small SMD resistors factory-tested one by one?
On 9/20/2020 2:02 PM, snipped-for-privacy@highlandsniptechnology.com wrote:
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For the best quality you have to do both I believe. Testing each units  
rejects duds at the individual level, and statistical sampling to reject  
bias or errors in your trimming and measurement apparatus at the process  
level.


Re: Are small SMD resistors factory-tested one by one?
On Tuesday, September 22, 2020 at 6:22:56 PM UTC-7, bitrex wrote:
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amples,or automatic test one by one;
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rs(or other passive components).The same question could be extended to semi
conductors,despite test on wafer is probably easier, by mechanical point of
 view,what about the sealed component?
Quoted text here. Click to load it
  
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It's next to impossible for a small company to reproduce the testing done b
y today's electronic component manufacturers. The only reason to do so is t
o sub-select parts for a tighter spec than the manufacturers.

Sealed lead-acid batteries are another story, however. I did not use these  
in my products, but I have consumed them in my aircraft. I do 100% incoming
 inspection and testing, and annual retesting to ensure performance. I have
 switched to LiFePO4 batteries where possible. Their quality is much higher
, along with their cost.

Re: Are small SMD resistors factory-tested one by one?
On 9/20/2020 1:28 PM, blisca wrote:
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Statistical sampling can ensure whole batches are very close to perfect,
like with prescription drug manufacturers. Testing pills is destructive,  
though, so obviously they don't test each one in that biz they do it  
statistically and set up the manufacturing process with hard limits so  
if it's going to be off it's going to be off-low.

To ensure there are exactly 0 out-of-spec resistors in a batch you have  
to test each one there's no way around it and for precision resistors  
that's what they do, they're easier to test as individuals than pills.

But I believe for the best quality they also do batch sampling because  
there can be errors in your overall process that just testing  
individuals may not detect. No "precision" manufacturing pr mechanical  
process stays precision forever, there's always some drift, and what  
happens if your manufacturing apparatus and test apparatus drift the  
same way, just sampling individuals won't detect that.

Re: Are small SMD resistors factory-tested one by one?
On 9/22/2020 9:42 PM, bitrex wrote:

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Just testing individuals, rather

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