Amateur electronics in danger due to lack of DIP ICs - Page 3

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Re: Amateur electronics in danger due to lack of DIP ICs
snipped-for-privacy@decadence.org wrote in news:s13h3f$1o0e$1
@gioia.aioe.org:
snip




  Forgot to mention that reduced pressure is always nice (read  
contributory to the evaporation and evacuation of water throughout the  
assembly.

Re: Amateur electronics in danger due to lack of DIP ICs
wrote:

Quoted text here. Click to load it

We have a giant water-wash machine, built around a modified Kenmore
dishwasher.

--  

John Larkin         Highland Technology, Inc   trk

The cork popped merrily, and Lord Peter rose to his feet.  
We've slightly trimmed the long signature. Click to see the full one.
Re: Amateur electronics in danger due to lack of DIP ICs
Re: Amateur electronics in danger due to lack of DIP ICs
On Mon, 22 Feb 2021 08:24:38 -0800 (PST), Deane Williams

Quoted text here. Click to load it

I buy little surface-mount adapters. We don't stock any DIP packaged
ICs any more.

https://www.dropbox.com/s/v5m4i3v8gvlnikb/Z356_Top.JPG?raw=1

https://www.dropbox.com/s/opnxfnk79o5lk1s/Z466_2.JPG?raw=1

https://www.dropbox.com/s/zaftysxtgclxj82/Z412_Proto.JPG?raw=1

The soldering trick is to go ahead and glob all the pins with solder,
short them together. Then use solder wick to slurp off the excess.

You can also lay out a 2 or 4-layer PCB and have a cheap quick-turn
house make a few. That's better than hand wiring for complex stuff.

Hey, I was scared of 1206 parts once. Now they look gigantic.




--  

John Larkin         Highland Technology, Inc   trk

The cork popped merrily, and Lord Peter rose to his feet.  
We've slightly trimmed the long signature. Click to see the full one.
Re: Amateur electronics in danger due to lack of DIP ICs
On 23/02/21 00:40, John Larkin wrote:
Quoted text here. Click to load it

Just so :)

Re: Amateur electronics in danger due to lack of DIP ICs
On Tue, 23 Feb 2021 15:41:37 +0000, Tom Gardner

Quoted text here. Click to load it

But I hate 0402s and smaller. They are difficult to manage by hand and
tombstone in production. Since we use reference designators and need
vias and traces too, there's not much advantage going below 0603.

--  

John Larkin         Highland Technology, Inc   trk

The cork popped merrily, and Lord Peter rose to his feet.  
We've slightly trimmed the long signature. Click to see the full one.
Re: Amateur electronics in danger due to lack of DIP ICs
John Larkin wrote:
Quoted text here. Click to load it

They're a win with microwave parts, though, and N in parallel between  
topside pours (with mega via-stitching on the ground pour) makes a  nice  
low-inductance bypass.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
We've slightly trimmed the long signature. Click to see the full one.
Re: Amateur electronics in danger due to lack of DIP ICs
On Tue, 23 Feb 2021 11:48:22 -0500, Phil Hobbs

Quoted text here. Click to load it

We use the sideways caps for fast stuff, like 0306s. They are short in
the dimension that matters.

For AC coupling, calculate the trace width and pick a cap just about
that wide to bridge the gap.

--  

John Larkin         Highland Technology, Inc   trk

The cork popped merrily, and Lord Peter rose to his feet.  
We've slightly trimmed the long signature. Click to see the full one.
Re: Amateur electronics in danger due to lack of DIP ICs

Quoted text here. Click to load it

  With the density level of your instrumentation circuits, you could  
(should) hand assemble the first articles anyway. Maybe even the  
entire production, short of bga devices and even those can be hot air  
mounted. And you would only need reference designators on those parts  
which are integral to fault determination on a 'broken board'.  A  
good technician shouldn't need a road sign on every corner to trace  
out a circuit during a diagnostic as long as a few key elements get  
tagged. And a grid reference 'sheet' would be easy as well.

  With HV designs, we didn't go much below 0805 and HV sections had  
slots between pads.  Anything smaller would likely not be very  
durable.
I hand soldered hundreds of tiny HV power supplies that a couple  
years of development and customer decision based mid design  
alterations, ultimately pumped a single 15kV output with medical  
grade human contact circuit interruption current shutdown trigger  
well below the spec on current and clamp time.  I think it was like  
11 milliseconds and 10 microamps.

Re: Amateur electronics in danger due to lack of DIP ICs
On Tue, 23 Feb 2021 18:42:07 +0000 (UTC),
snipped-for-privacy@decadence.org wrote:

Quoted text here. Click to load it

Fine pitch, LGA, and BGA are normal. Those don't work by hand.

 Maybe even the  
Quoted text here. Click to load it

Hand assemble without reference designators?  

Hot air doesn't control temperature profiles, or prevent oxidation. We
have a reflow oven with nitrogen. That's the way stuff is built now.

Quoted text here. Click to load it

How do I get ref desigs on SOME of the boards? Add as needed?

Quoted text here. Click to load it

Manufacturing, test, and engineering all want reference designators. I
want ref desigs. 50 mils high is about as small as works for everyone.

Quoted text here. Click to load it

Better you than me.

--  

John Larkin         Highland Technology, Inc   trk

The cork popped merrily, and Lord Peter rose to his feet.  
We've slightly trimmed the long signature. Click to see the full one.
Re: Amateur electronics in danger due to lack of DIP ICs

Quoted text here. Click to load it

  Comes from also being the one that did the layout, and from circuit  
familiarity.

Re: Amateur electronics in danger due to lack of DIP ICs
On Tue, 23 Feb 2021 20:22:09 +0000 (UTC),
snipped-for-privacy@decadence.org wrote:

Quoted text here. Click to load it

But we manufacture and sell products. The production people know how
to assemble but generally don't understand the electronics. My layout
people don't understand electronics either.

We design something and formally release the rev A drawings. We never
prototype an entire product, and usually don't breadboard or protoype
at all. We're engineers.

Manyfacturing sets up the P+P stencils and programming and builds a
few rev A units, and we test them and finish off code. We expect rev A
to be sellable, and it usually is.

Even on a quick-turn proto board, I want reference designators.

--  

John Larkin         Highland Technology, Inc   trk

The cork popped merrily, and Lord Peter rose to his feet.  
We've slightly trimmed the long signature. Click to see the full one.
Re: Amateur electronics in danger due to lack of DIP ICs

Quoted text here. Click to load it

Like I said, I don't think your circuits are all that dense.

Wouldn't be hard with the engineering printouts of the schematics and  
trace layouts.  Sheesh.

 The silk screen and the ref des in the schematic are two different  
things.  You do not have to print them all. In HV sections you can't if  
you know what you are doing.  The multiplier section doesn't even get a  
mask layer.

Re: Amateur electronics in danger due to lack of DIP ICs
On Tuesday, February 23, 2021 at 8:20:48 AM UTC-8, John Larkin wrote:
Quoted text here. Click to load it

I've found it to be possible to avoid tombstoning, or at least cut it way down,
by making sure there's a similar amount of copper on both sides of each part.  
If one end of a part is soldered to a large copper area without thermal reliefs while  
the other has a single 5-mil trace, it's almost guaranteed.  If the copper distribution
is well-balanced, it essentially never happens.

For hand work, 0402 is really no less manageable than 0603.  An advantage is
parts availability.  The big lesson I learned from the last MLCC shortage was that  
when the vendors drop the balls, they drop them in decreasing order of size.  They  
shut down their 1206 and 0603 lines before they shut down 0402 and smaller.

0201 is manageable with a microscope.  I've avoided them on PCBs in the past, but
will probably start using more of them for prototyping, having been impressed at how  
convenient they are at bypassing QFNs.  They fit right between the peripheral pads
and the central ground pad:
http://www.ke5fx.com/qfn_0201.jpg.  

At that point, dead-bug construction offers better SI than the best PCB layout, at least  
as far as bypassing is concerned. :)

-- john, KE5FX

Re: Amateur electronics in danger due to lack of DIP ICs
On 2/23/2021 11:20 AM, John Larkin wrote:
Quoted text here. Click to load it

The US8/VSSOP8 is a dreadful package to hand-solder, unfortunately some  
nice parts like very high speed flip-flops seem to only come in that one.

Re: Amateur electronics in danger due to lack of DIP ICs

Quoted text here. Click to load it

I had to make my own US8 adapters. Some really nice parts come only in
US8, like 1 ns cmos gates and flops, and some outrageous triple
buffers.

https://www.dropbox.com/s/ifnvctd6yg68dtu/US8s.jpg?raw=1

I included a bypass cap on that one. There are some variants.

--  

John Larkin         Highland Technology, Inc   trk

The cork popped merrily, and Lord Peter rose to his feet.  
We've slightly trimmed the long signature. Click to see the full one.
Re: Amateur electronics in danger due to lack of DIP ICs
On Tue, 23 Feb 2021 19:31:00 -0800, John Larkin

Question John:

I assume you cut your layouts with a Dremel tool?  How do you get your
lines so straight and smooth?  Do you use a guide or something.  My
hands are far too unsteady to get anywhere that neat,

John

Quoted text here. Click to load it

Re: Amateur electronics in danger due to lack of DIP ICs
neonjohn wrote:
Quoted text here. Click to load it

You can't be the real Neon John--he never top-posted.  Who are you  
really? ;)

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
We've slightly trimmed the long signature. Click to see the full one.
Re: Amateur electronics in danger due to lack of DIP ICs

Quoted text here. Click to load it

  It was not exactly a top post.  He did frame his question above  
what he quoted from Larkin, but top posters flat put everything above  
the entire previous post.

Re: Amateur electronics in danger due to lack of DIP ICs
That's me.  Agent opens the reply at the top so that's where I write.
Don't you enjoy not having to scroll through hundreds of lines of
quotes which should have been snipped?

John



On Wed, 24 Feb 2021 15:23:59 -0500, Phil Hobbs

Quoted text here. Click to load it

Site Timeline