# Hexagonal Die

By: dmcq (dmcq.delete@this.fano.co.uk), July 6, 2022 3:00 pm
Adrian (a.delete@this.acm.org) on June 27, 2022 10:24 pm wrote:
> Math Nerd (math.nerd.delete@this.nerds.com) on June 27, 2022 5:05 am wrote:
> > > It is a tad more expensive but not a significant cost in relation to a finished wafer on a modern
> > > process. The biggest reason you don't want to do it is the loss of edge area for I/O.
> >
> > The perimeter of a rectangle with a 2:1 aspect ratio is only 14% more than the perimeter of a regular
> > hexagon with the same area. The perimeter of a square is only 7% more than the perimeter of a regular
> > hexagon with the same area. If anyone would make a hexagonal die, it would be for the largest die,
> > because they have the most wasted area on a circular wafer. The largest die today all use flip chip
> > area bonding, not edge bonding. There seems to be a trend to use chiplets today instead of large
> > dies and that reduces the wasted area near the circumference of the wafer.
> >
> > In any case, the ability to make non-rectangular die is very interesting and surprising,
> > which I’m sure was the main reason you mentioned it. One semi-practical use for this technology
> > could be making microscopic chips where it would be better to not have sharp rectangular
> > corners, such as RFID tags for pets or sensors implanted under human skin.
> >
> > For the record, here is how I calculated that the perimeter of a rectangle with a 2:1
> > aspect ratio is 14% more than the perimeter of a regular hexagon with the same area:
> >
> > Perimeter of 2:1 aspect ratio rectangle with smaller side a is 6a (rectangle is a x 2a).
> > Perimeter of regular hexagon with side b is 6b.
> > Ratio is perimeters is a/b.
> > Area of a 2:1 aspect ratio rectangle with smaller side a is 2 a^2.
> > Area of a regular hexagon with side b is b^2 (3/2) sqrt[3].
> > Set areas equal: 2 a^2 = b^2 (3/2) sqrt[3]
> > a/b = sqrt[ (3/4) sqrt[3] ] = 1.14
>
>
>
> While making triangular dies would be almost as easy as making rectangular dies, they would have a higher risk
> of corner breakage during manufacturing and the internal areas near the corners might be used inefficiently
> due to difficulties in placing there devices and routing their connections without excessive crowding.
>
>
> Making hexagonal dies is certainly much more expensive, as there are no straight lines to separate the
> dies. The only way to cut the dies would be with a laser that cuts completely through the wafer.
>
> Especially for smaller hexagonal dies, there would be a problem how to manipulate
> the dies at the moment when they are cut loose. Picking the dies one by one,
> e.g. with a vacuum suction cup, would be very slow and expensive.
>
> The traditional cheap method was to glue the wafer on an elastic membrane, scribe the straight
> lines between the dies and then expand the elastic membrane to separate the dies. Thus the die
> separation was extremely fast and the individual dies remained attached to the membrane, there
> was no need for some special means to catch each die when it is detached, to prevent its fall.

That's basicaly how non-rectangular dies are separated too as described in a link earlier. The laser doesn't completely separate them, it weakends the lines like perforated paper and then the pulling separates them.
TopicPosted ByDate
OK dumb question timeDoug S2022/06/24 01:31 PM
OK dumb question timeanon52022/06/24 01:38 PM
Silicon ingots are round.Mark Roulo2022/06/24 02:29 PM
Silicon ingots are round.Squarehead2022/06/24 02:38 PM
Silicon ingots are round.Mark2022/06/24 03:00 PM
Silicon ingots are round.Gary Kopp2022/06/24 03:20 PM
Silicon ingots are round.Adrian2022/06/24 11:34 PM
Silicon ingots are round.tarlinian2022/06/24 03:38 PM
Silicon ingots are round.Doug S2022/06/24 11:13 PM
Silicon ingots are round.anon2022/06/25 11:34 AM
Silicon ingots are round.Doug S2022/06/25 11:39 AM
Silicon ingots are round.Groo2022/06/26 09:41 AM
Silicon ingots are round.Doug S2022/06/26 12:05 PM
Silicon ingots are round.Gtoo2022/06/26 02:55 PM
Silicon ingots are round.rwessel2022/06/25 11:43 AM
Not reallyGroo2022/06/26 09:39 AM
Not reallydmcq2022/06/26 10:56 AM
Not reallyGroo2022/06/26 02:58 PM
Not reallyanon22022/06/26 05:22 PM
Why not triangles? Anon2022/06/27 03:34 AM
Why not triangles? Math Nerd2022/06/27 04:52 AM
Why not triangles? Math Nerd2022/06/27 05:45 AM
Don't forget Penrose Tiling (NT)ananon2022/06/27 06:06 AM
Why not triangles? Doug S2022/06/27 07:43 AM
Why not triangles? Anon2022/06/27 08:33 AM
Die shape that minimizes wasted area on circular wafersMath Nerd2022/07/01 09:20 PM
Die shape that minimizes wasted area on circular wafersBrett2022/07/02 02:35 PM
Die shape that minimizes wasted area on circular wafersMath Nerd2022/07/02 04:15 PM
Die shape that minimizes wasted area on circular wafersMark Roulo2022/07/02 04:41 PM
Die shape that minimizes wasted area on circular wafersDoug S2022/07/02 06:44 PM
Die shape that minimizes wasted area on circular wafersBrett2022/07/03 12:31 AM
Die shape that minimizes wasted area on circular wafersAdrian2022/07/03 10:25 PM
Die shape that minimizes wasted area on circular wafersanon22022/07/03 11:33 PM
Die shape that minimizes wasted area on circular wafersBrett2022/07/04 12:45 AM
Die shape that minimizes wasted area on circular wafersdmcq2022/07/04 06:09 AM
Die shape that minimizes wasted area on circular wafersJames2022/07/04 09:52 AM
Die shape that minimizes wasted area on circular wafersdmcq2022/07/04 10:26 AM
Die shape that minimizes wasted area on circular wafersAdrian2022/07/05 03:28 AM
Cannon Lake vs Kaby LakeMark Roulo2022/07/04 10:30 AM
C-class bonusesblue2022/07/04 12:27 PM
C-class bonusesanonymou52022/07/04 03:23 PM
Die shape that minimizes wasted area on circular wafersanon22022/07/04 06:53 AM
Die shape that minimizes wasted area on circular wafersBrett2022/07/04 12:32 PM
Die shape that minimizes wasted area on circular wafersFoyle2022/07/04 01:30 PM
Die shape that minimizes wasted area on circular wafersAnon2022/07/04 01:37 PM
What is a mirrored die?Mark Roulo2022/07/04 02:59 PM
What is a mirrored die?Brett2022/07/04 03:32 PM
What is a mirrored die?Doug S2022/07/04 10:08 PM
Die shape that minimizes wasted area on circular wafersanonymou52022/07/04 03:12 PM
Die shape that minimizes wasted area on circular wafersFoyle2022/07/05 10:41 AM
Die shape that minimizes wasted area on circular wafersanon22022/07/04 04:52 PM
Die shape that minimizes wasted area on circular wafersUngo2022/07/05 06:24 PM
Die shape that minimizes wasted area on circular wafersBrett2022/07/05 07:56 PM
Die shape that minimizes wasted area on circular wafersanonymou52022/07/06 05:46 AM
Die shape that minimizes wasted area on circular wafersdmcq2022/07/06 02:55 PM
Die shape that minimizes wasted area on circular wafersMark Roulo2022/07/06 04:09 PM
Die shape that minimizes wasted area on circular wafersDoug S2022/07/06 05:31 PM
Example of mirrored wafer?Mark Roulo2022/07/04 06:01 PM
Not the same as 3-core CPU from a 4-core dieMark Roulo2022/07/04 09:31 AM
Great comment, thank you (NT)anon22022/07/06 12:00 AM
crystal latticehobold2022/06/27 12:09 PM
crystal latticedmcq2022/06/27 03:58 PM
Given path dependency I doubt it ...Mark Roulo2022/06/27 06:02 PM
Given path dependency I doubt it ...Adrian2022/06/27 10:01 PM
Hexagonal DieMath Nerd2022/06/27 05:05 AM
Hexagonal Diedmcq2022/07/06 03:00 PM
Silicon ingots are round.dmcq2022/06/25 02:38 PM
Silicon ingots are round.dmcq2022/06/25 02:43 PM
Silicon ingots are round.aaron spink2022/06/25 03:05 PM
Notch on Silicon WafersEric P2022/07/01 04:07 PM
Still there, I think ...Mark Roulo2022/07/01 04:47 PM
Still there, I think ...Eric P2022/07/01 05:26 PM
Still there, I think ...tarlinian2022/07/01 06:50 PM
Still there, I think ...David Kanter2022/07/02 09:14 AM
Still there, I think ...Mark Roulo2022/07/01 09:31 PM
Still there, I think ...Eric P2022/07/02 12:10 AM
OK dumb question timeanonymouse2022/06/24 03:47 PM