How do i go smaller than SMT

[kybert]

I have a project that i first prototyped on breadboard, then to veroboard, then to PCB, then SMT PCB.

It works 100% and has been tested in almost every possible way, but it is too large...

I need the product to be about 1cm x 1cm, including a lithum battery, and only 1-2mm think (ideally flexable).

I've seen the inside of calculators, there is a small black blob that contains the circuits, im assuming just a wafer of silicon is under the blob.

How do i get my circuit put in this format?

Im using a PIC microcontroller, will this be a problem? I doubt that microchip will release the raw wafer of their product...

The uP is really a must, as it preforms some quite tricky timing tasks.

 

[Exo]

Microchip sells raw wafers, but the minimum order is probabely a couple of 1000...
Also, you have to be able to handle a raw wafer, if it gets dust on it then its broken...

How many pins does your application require on the PIC?
if it's 4 or less you could always take a look at the PIC10F series...
basically the 12C core in a SOT23 package

 

[Nigel Goodwin]

I've seen the inside of calculators, there is a small black blob that contains the circuits, im assuming just a wafer of silicon is under the blob.

How do i get my circuit put in this format?

'You' probably don't, it's not something you could do at home, presumably it needs very expensive machines to make it possible?.

Im using a PIC microcontroller, will this be a problem? I doubt that microchip will release the raw wafer of their product...

As Exo says, I'm sure MicroChip will happily sell you wafers, plenty of other products use them - but, presumably, you need large order quantities and the technology to use them.

If you want a wafer to try and play with, try getting hold of a PIC based smart card and removing the wafer - they usually use the 16F84.

Assuming this is for a commercial product you would probably be better off sub-contracting the construction to a company experienced in this type of project - and who already have the required equipment to do the job. I suspect you would need to be ordering in the thousands to make it viable, it's probably only one or two steps below having a custom IC built.

Possibly MicroChip would be able to make recommendations on suitable companies for such tasks?.

 

[evandude]

the "black blob" chips are referred to as "chip on board" devices... you can often buy devices in this format; you're not going to get a raw wafer (you would then have to cut it)... you will just get individual die cut out of the wafer. you'll still be up the creek without a paddle though, since there's no way you'll be able to extrude extra-fine gold wires from the aluminum bond pads on the couple-millimeters-square die.

as others said, the only way you're going to be able to do COB is to contract it out to a company that has the equipment and experience. otherwise, you'll need to just find the smallest-package PIC that you can.

 

[Styx]

you can get some bloody smal serial PIC's if you really want to shrink your board right donw

 

[kybert]

you can get some bloody smal serial PIC's if you really want to shrink your board right donw

Serial pics? Havn't heard of them ?!




-- As for the PIC10F, it appears to not be released yet - but would be an ideal device.

 

[Styx]

give me a few days, they are always advatised in "electronics weekly" and I have thrown out this weeks,

I'm pretty sure that they were serial PIC chips???

 

[Electric Rain]

Can I see the schematics? I'm pretty good at designing compact PCBs in my PCB creation program. I'll get it as small as I can if you let me see the schematics. That's about all I can do to help. :lol:

 

[kybert]

hi,

Still finalising the design. Having a few problems finding the required components and at RF freequencies, PCB track length has a relivent inductance (~10nH/inch), so this can be used to change the value of an inductor if required (and i think it will be required).


When i have a sch, i shall post and let everyone decide if its at-all possible.

Looks like i may have to sub-contract the PCB design as well as production to a company with RF layout experience, as doing it myself will be next to impossible.