Author Topic: Stop using 0603 or bigger resistors and capacitors?  (Read 2552 times)

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Offline Faringdon

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Stop using 0603 or bigger resistors and capacitors?
« on: June 27, 2021, 01:56:37 pm »
Hi,
Due to the shortage of 0603 and bigger resistors and capacitors, its recomended to use 0402 and lower. (where power levels/voltages allow)
This seems a bit drastic doesnt it?
Is the manufacture of 0603 and bigger resistors and capacitors so complex that extra plants wont be set up to produce them?

0402's are terrible as resistors have no value on them, and they seem to tombstone/head-on-pillow  more.
(unless you have massive PCB runs where you can tweak the solder bath temperature and ramp profile to eventually get it perfect every time)

« Last Edit: June 27, 2021, 02:30:49 pm by Faringdon »
 

Online evb149

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #1 on: June 27, 2021, 03:25:56 pm »
I don't have any insight about the supply problems.

Yeah finding ones with markings is not always easy, though I seem to recall seeing some 0402s that are marked from some vendor(s).  Perhaps a bad memory.

As for tombstoning, though, there's no good reason that should happen with good PCB design and soldering technique:

1: Design pads per. IPC or vendor suggestions for size and shape and spacing.

2: Design solder paste mask per. vendor suggestions for layer thickness, aperture size/shape/vs. land pad size and type of solder.

3: Make the thermal environment and effective wettable pad area the same for both pads.  E.g. if a pad is connected to a plane, use thermal relief so the other pad's connections and heat sinking will be similar in width and conductivity. 

4: Make trace / net to pad connections symmetric -- If one trace exits the pad with say 0.2mm width, make the other pad's trace / net connection do the same from the corresponding edge of the pad.  Don't make one pad exit sideways and the other pad exit from the end or the opposite side.  Symmetry.

5: Preheat your boards and follow the ramp-up to reflow profile approximately so the pads will have generally equal temperatures as the soldering begins before reflow and equal cooling after reflow.

6: Use smaller traces (neck down) when they enter the pad so the size of the trace is significantly smaller than the pad at least within the area where the solder mask is open around the pad.  i.e. keep it symmetric and don't let one pad's solder wick off to a large trace / plane much more so that will happen on the other pad.

You should have no real problems with 0402 in these ways even for manual rework without using a paste stencil.

 
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Offline Feynman

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #2 on: June 28, 2021, 07:23:33 pm »
Yeah, "vendor suggestions" is the right thing to do. For professional and/or high volume production your assembler is most likely able to tell you what footprint geometries work best, i. e. reduce the probability for tomb-stoning. And that is not necessarily an IPC compliant footprint.
 
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Online asmi

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #3 on: July 01, 2021, 08:04:00 pm »
I've been using 0402 parts for years now pretty much everywhere (except where larger parts are required due to voltage/current/power regime). Didn't notice any excessive tombstoning compared to larger parts. But they are much more convenient for layout due to their small size, as space on multi-layer boards is always at premium.
 
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Offline SiliconWizard

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #4 on: July 01, 2021, 08:19:31 pm »
0402 and smaller are hard to handle (well, 0402 is still OKish) for hand soldering, but otherwise, they are fine.

Of course, 0402 can be used only if you don't exceed its max power rating, which is significantly lower than for 0603 for resistors. So it's not possible to replace those in all cases.

As far as tombstoning goes, I've never seen any issue with 0402. You'd probably have to deal with a pretty bad PCB design for this to happen. OTOH, 0201 is a lot trickier.
 
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Online asmi

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #5 on: July 02, 2021, 06:18:16 pm »
OTOH, 0201 is a lot trickier.
I do use 0201s from time to time (mostly for decoupling of big BGAs when 0402s do not fit inside the via field), but only ever had it tombstone once. They are a bit of PITA to place even with proper equipment (a stereo microscope and a good pickup tool), and you have to be extra precise with your stencil printing, so I only use them when there are no other options.
Also 0201s are a lot more expensive than 0402s, so there is less financial incentive to use them, unlike the case of 0402s compared to larger parts, when 0402 are almost always cheaper than anything larger.
 
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Offline Faringdon

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #6 on: July 06, 2021, 04:33:15 pm »
Thanks, these are great replies.

Also, purely from a supply (threat of nil-stock) viewpoint only, do you think you have more chance of suffering supply issues with 0603 capacitors and resistors than with 0402 capacitors and resistors?

Why would an individual PCB assembly company instruct you that you have a danger of short_supply if you choose 0603 size over 0402 size?
« Last Edit: July 06, 2021, 04:44:53 pm by Faringdon »
 

Offline SiliconWizard

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #7 on: July 06, 2021, 06:02:01 pm »
Why would an individual PCB assembly company instruct you that you have a danger of short_supply if you choose 0603 size over 0402 size?

My guess is that they are anticipating shortage based on market knowledge...

As you can read here (for instance): https://www.prnewswire.com/news-releases/global-and-china-automotive-multi-layer-ceramic-capacitor-mlcc-markets-2020-2026---some-vendors-have-pivoted-to-the-automotive-mlcc-market-301210903.html

It's only talking about caps (MLCC), but quoting:
Quote
Of a wide range of automotive MLCC models, those with size ranging from 0402 to 2220 are in use while 0603, 0805 and 1206 get most utilized.
 
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Offline Faringdon

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #8 on: July 07, 2021, 04:47:17 pm »
Thanks, i see what you mean, if you take the fact that 0603's etc are more used, then it corresponds that they are more likely to go nil-stocked, but i am not sure that really corresponds?
 

Offline thm_w

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #9 on: July 07, 2021, 09:06:27 pm »
Thanks, i see what you mean, if you take the fact that 0603's etc are more used, then it corresponds that they are more likely to go nil-stocked, but i am not sure that really corresponds?

STM32F103 is one example, incredibly common and widely used, now impossible to find for a reasonable price. Meanwhile many more obscure items are in stock (eg ATSAMD).
Although with 0603's you have far more alternate options.

Its all speculation though.
 
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Offline Siwastaja

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #10 on: July 08, 2021, 03:29:22 pm »
If the shortages were easy to predict, everybody would be making big money playing the game of buying and selling. In reality, it's very hard to predict. Any such attempt will only backfire (except by luck). The only two real solutions, really, are;

1) Be ready to adapt new components, packages, etc., on a quick cycle, using what is available now, not trying to see what is available half a year from now,
2) Order everything you need in early stage of design so that you can start the layout work etc. once you have the parts. Yes, you need to stock for a long time. Yes, this sucks and you need capital for the inventory and lose money if you have to change design midway or fail to sell all units.

OTOH, if you now decide 0603 is bad and design with a 0402 part the opposite may happen and you find yourself redesigning with 0603 parts because they now suddenly are available better.

Quite frankly, if you can't handle 0402 in a professional setting being a pro designing for living, for a product to be professionally manufactured, you are not up to the task. This is the state of the art integration size of late 1980's and extremely commonplace already early in 2000's. When talking about hobby, I accept some people have difficulties with 0402 size, still I recommend to at least try until you are sure you can't learn to use this size. Prototyping for professional work, OTOH, doesn't need to be enjoyable or fun, some components can be PITA to solder, it's still 0.01% of design time so doesn't make significant productivity issue.
« Last Edit: July 08, 2021, 03:36:20 pm by Siwastaja »
 
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Offline SiliconWizard

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #11 on: July 08, 2021, 05:37:34 pm »
If the shortages were easy to predict, everybody would be making big money playing the game of buying and selling. In reality, it's very hard to predict.

Yes. Not only that, but making predictions inevitably impacts the outcome, particularly if you make them known and are half-credible.
 
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Offline Uky

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #12 on: July 20, 2021, 07:33:58 am »
Regardless of the shortage and that some assembly operators do not have the capacity to handle 0201
there are another thing to consider. When using ceramic capacitors, it could be tempting to use
as small as possible since there are materials with high volume efficiency like Y5V or Z5U.
The problem is that the capacitance are temperature dependant and also exhibit piezo-electric
properties. For professional use, I always go with NP0/C0G for smaller values and X7R för larger.
Choosing that for start, results in larger sized capacitors. But I do agree: It can be very difficult
to place these inside the court-yard of the secondary side of a board populated with BGA's...
 
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Offline peter-h

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #13 on: July 21, 2021, 06:47:18 pm »
I still use 0805 (1206 for precision ones) and do to 0603 only if need smaller parts. No issues with availability.

Below 0603, resistors are not marked.
Z80 Z180 Z280 Z8 S8 8031 8051 H8/300 H8/500 90S1200 32F417
 
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Offline fcb

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #14 on: July 21, 2021, 07:28:11 pm »
Where are you getting this data from Treez?

0805/1206 still readily available - huge numbers of designs use them (including us), they'll be here for many decades to come. Use the size parts that suit your application! Our typical 0805 pad can take a 1206 and also an 0603, 0603 can also take an 0402, etc...

Head-in-pillow defects are usually a result of poor-wetting, if you are getting these defects the fault probably lies with solder paste type (& age) and reflow profile.




https://electron.plus Power Analysers, VI Signature Testers, Voltage References, Picoammeters, Curve Tracers.
 
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Offline Kleinstein

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #15 on: July 22, 2021, 11:55:32 am »
The passives are usually the smaller problem, as there are often alternative manufacturers, at least for the normal parts. When you need somerhing special, like 1 kV capacitor, 1ppm/K resistors the size is anyway not the main factor to consider and they may come in larger case only.

There was the shortage of MLCCs, but now we have a shortage with chips and this quite some chips first going to storage and thus a tendency to see less need for the common passives. So I don't expect a new shortage of those small parts.
With the resistors one can usually choose an alternative part, often even a different package on the same pads if really needed.  Changing the PCB to also take smaller size is usually not a big deal.  Going up can be more tricky.

It is much worse with the semiconductors. Many have no easy pin compatible direct replacement. Even some relatively common parts get short on supply - at least with a chance to find higher price substitutes, though these also can run out fast. Special/unique parts are effected too.
 
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Offline Shadowfire

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #16 on: September 15, 2021, 08:39:04 pm »
IC shortages suck right now, I've never seen anything like this before.  My current PCB has ~1400 components with around 160 unique components.
Its normal for a board with this many unique components to have to re-spec 1-3 of the chip capacitors or resistors when PCB's are done (as Digikey may no longer have that particular part available).
This last time I had to respec over 20 of the components, most of which were IC's.  I made it a point to order the components before the boards this time, and I'm glad I did, as several IC's were unavailable in the preferred package and I had to rework the board for the package that was in stock.  This is an automotive board prototype, and I even had to stick non-automotive IC's on this one, as the AEC qualified variants are currently unobtainium.  At least it allows the software people to start working with the board.  I'm still a bit worried as the uP I'm using (NXP S32K144) is out of stock EVERYWHERE in N.A. and everyone is stating December 2022 for restock.

If you're thinking about playing 3-shell monty with resistor/capacitor package sizes, I recommend just laying out your board for 0805 everywhere, as it is the biggest package (but DON'T route a trace between the pads).  You can then go back and move to smaller footprints without having to knock other components around due to lack of space, you just have to fix pad entries.  It goes without saying, but double check your capacitor voltage ratings, and resistor power ratings, when moving to the smaller footprints.
 

Offline LoveLaika

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Re: Stop using 0603 or bigger resistors and capacitors?
« Reply #17 on: September 15, 2021, 08:42:03 pm »
Personally, while I prefer 0603s or higher, I made sure that my generic, 2-terminal components like resistors and capacitors, can take 0402s and 0603s so I'm not limited to one or the other.
 


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