Grinding end of ceramic EPROM - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: January 29, 2015, 07:18:32 am
content: A number of boards I made a long time ago are in need of an update so I made a daughter board that plugs into two existing ic sockets. Trouble is, it is a fairly tight board and there is an EPROM that slightly intrudes into the space occupied by the daughter board. I tried grinding about 1/2 mm off the end of the EPROM but it is as hard as I don't know what! Short of going for a OTP plastic package, is there a practical way of grinding a bit off the ceramic EPROM package?

author: Paul Moir
author_rank: Frequent Contributor
timestamp: January 29, 2015, 07:25:07 am
content: Diamond wheel, such as the type used for cutting ceramic tile goes through them like butter. You can get them in dremel size, angle grinder size or larger fairly cheaply. If you can drip some water while cutting it'll keep the dust and heat down.

author: AndyC_772
author_rank: Super Contributor
timestamp: January 29, 2015, 07:50:09 am
content: Can you not just stack the daughter board a bit higher by plugging in another couple of IC sockets?Seems a shame to risk damaging components that are no longer manufactured.

author: pickle9000
author_rank: Super Contributor
timestamp: January 29, 2015, 07:55:54 am
content: I have a portable dental drill. Not a common tool but great for ceramics.

author: SL4P
author_rank: Super Contributor
timestamp: January 29, 2015, 11:34:23 am
content: Photo?It seems that the 2mm (limit?) you could risk shaving off the EEPROM, would come off the daughter board more easily - even if it needs a kludge wire to replace a lost track close to the edge...

author: Circlotron
author_rank: Super Contributor
timestamp: January 29, 2015, 12:24:38 pm
content: Daughter board has a male-to-male adapter that goes into the ic socket underneath and this adapter is right at the edge of the daughter board. There is absolutely no space. I tried attacking an eprom today on a belt sander and wow are they hard! No hope. I might just try an OTP plastic eprom before I go too far.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 29, 2015, 12:54:06 pm
content: The ceramic is alumina (Mohs 9), so you need carbide or diamond anything to even touch it. Use water or other coolant.The very ends should be safe to grind, electrically speaking (up until you start cutting into the leads), but I don't know how deep the sealing compound (fused glass frit I believe) goes before the internal cavity (with the chip) will be exposed.Tim

author: SeanB
author_rank: Super Contributor
timestamp: January 29, 2015, 07:24:16 pm
content: Depending on who made it and when it might have a kovar leadframe, or even a screen printed set of traces. The leadframe will be covered with the glass frit till almost at the window, but there will be some voids down the centre. Probably best to use the OTP plastic, as that will have the kovar leadframe only, and you just grind till you touch the end of the leadframe by the pins. Do not go further as you will cut the thin parts of the leadframe and kill the chip.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 29, 2015, 10:52:27 pm
content: Wonder what the resonant frequency of the bond wires is...