Author Topic: MSOP clearances for Seeed Studio  (Read 6153 times)

0 Members and 1 Guest are viewing this topic.

Offline HackedFridgeMagnetTopic starter

  • Super Contributor
  • ***
  • Posts: 2028
  • Country: au
MSOP clearances for Seeed Studio
« on: October 30, 2012, 05:15:55 am »
Just trying to get my layout right so Seeed can manufacture my board.

According to Seeeds design rules I don't think they can technically manufacture footprints for MSOP devices.
But on the other hand I am sure they do it every day.

I just want to get my clearances right so my board is ok.

Attached are:
my proposed pad arrangement.
the relevant part of the Data sheet for the  LT3652
seeed studios design rules.

Is my proposed layout a fail, or is it ok, or could I improve it? Maybe making the solder mask width 4mil would be ok, but I don't want to go to the limit of their tolerances if I can help it.

I think I could possibly make the pads longer and thinner than the data sheet.

I guess the rule that confuses me is 'Min solder mask clearance'. Is this just the clearance between two bits of solder mask or the clearance between solder mask and copper?




 

Online Mechatrommer

  • Super Contributor
  • ***
  • Posts: 11629
  • Country: my
  • reassessing directives...
Re: MSOP clearances for Seeed Studio
« Reply #1 on: October 30, 2012, 06:14:42 am »
its about the same as iteadstudio they used the same fab house anyway from what i read i keep my limit to 0.31mm so there's no problem to meet their 0.15mm limit. now to your footprint is 0.65mm pitch there should be no problem but why the pad is so 0.42mm thick it will be very close to each other, calculating its 0.65 - 0.42 = 0.23 well, no problem :P but wait, pin to power (center) pad is (5.23 - 2 x 0.889 - 1.651) / 2 = 0.9mm epic fail! reduce size of those pad(s) very ok!.
« Last Edit: October 30, 2012, 09:46:46 am by Mechatrommer »
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline HackedFridgeMagnetTopic starter

  • Super Contributor
  • ***
  • Posts: 2028
  • Country: au
Re: MSOP clearances for Seeed Studio
« Reply #2 on: October 30, 2012, 08:13:24 am »
thanks for the input.

0.9mm separation should be ok shouldn't it.


Quote
i keep my limit to 0.31mm
Is that a copper separation distance of 0.31mm?

But how much  margin do you use around the copper for the solder mask? Any?





 

Online Mechatrommer

  • Super Contributor
  • ***
  • Posts: 11629
  • Country: my
  • reassessing directives...
Re: MSOP clearances for Seeed Studio
« Reply #3 on: October 30, 2012, 09:45:46 am »
0.9mm separation should be ok shouldn't it.
bum! 0.9 sometime looks like 0.09 to me! that what happen to me when calculating while typing. 0.9mm should be very ok!.

Quote
i keep my limit to 0.31mm
Is that a copper separation distance of 0.31mm?
i guess separation means clearance? if so, yes.

But how much  margin do you use around the copper for the solder mask? Any?
no or i'm not yet aware of how to specify that in diptrace. it automatically created for me :(

FWIW attached are my diptrace design rule setting last time i edited based on itead's rule (3rd pic), i hope i didnt miss something as i already sent my 1st board to them, hope it will not screwed, i also learning. i need to recheck those rules thouroughly again. if you set those rules in your eda, it should be able to warn you about this.
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline HackedFridgeMagnetTopic starter

  • Super Contributor
  • ***
  • Posts: 2028
  • Country: au
Re: MSOP clearances for Seeed Studio
« Reply #4 on: October 30, 2012, 10:28:56 am »
It looks like a nice interface DRC in diptrace. but It doesn't seem to specify the clearance I am interested in.

I might just set it to the 3.2mil in my diagram. It doesn't seem to do much.

 

Offline Spikee

  • Frequent Contributor
  • **
  • Posts: 568
  • Country: nl
Re: MSOP clearances for Seeed Studio
« Reply #5 on: October 30, 2012, 04:39:22 pm »
I had some breakouts made for the MCP4728 MSOP-10 at itead and they got out fine on all the boards.
Freelance electronics design service, Small batch assembly, Firmware / WEB / APP development. In Shenzhen China
 

Online Mechatrommer

  • Super Contributor
  • ***
  • Posts: 11629
  • Country: my
  • reassessing directives...
Re: MSOP clearances for Seeed Studio
« Reply #6 on: October 30, 2012, 06:03:16 pm »
It looks like a nice interface DRC in diptrace. but It doesn't seem to specify the clearance I am interested in.
if its about mask clearance, i can see there's option when exporting to gerber. its mask sweel and shrink i believe you'll be interested in mask swell, its defaulted to 0.1mm, i think its clearance to the copper pad.
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline HackedFridgeMagnetTopic starter

  • Super Contributor
  • ***
  • Posts: 2028
  • Country: au
Re: MSOP clearances for Seeed Studio
« Reply #7 on: October 30, 2012, 10:20:12 pm »
Yes it defaults to about 0.1mm in Kicad too. But if I use that then there isn't enough room for the pads and the min solder mask width.

Consequently I have made some adjustments, I will reduce the copper width a little, reducing the solder mask clearance around the pads to say 0.05mm from the default and having the solder mask thickness at about 0.2mm which is about the minimum.

pin pitch = copper pad + gap + mask + gap

0.65 = 0.35 + 0.05 + 0.2 + 0.05 (mm)

I will give this a go.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf