PCB Milling reccomendations

[magicniner]

and for this, a CNC is the WRONG solution.

Always with the negative waves Moriarty! ;-)
Milling away the board from the back actually makes perfect sense if you read the bit about epoxy in his description of why heat isn't best for this!
A manual micro-mill like the Proxxon suggested above would be a logical first step, you would need to stabilise the chip (hot glue & a fixture?) to stop it lifting into the tool path close to the end of machining and if it suits your application you could probably then CNC it and still stay within your budget.

- Nick

[PEU]

Always with the negative waves Moriarty! ;-)
Milling away the board from the back actually makes perfect sense if you read the bit about epoxy in his description of why heat isn't best for this!
A manual micro-mill like the Proxxon suggested above would be a logical first step, you would need to stabilise the chip (hot glue & a fixture?) to stop it lifting into the tool path close to the end of machining and if it suits your application you could probably then CNC it and still stay within your budget.

- Nick

This is the attitude that I like to hear! I have discussed a hand mill with colleagues and due to the parameters that we would have to work with wouldn't be an option, nobody here would trust themselves eyeballing the depth going through the PCB.

As for holding the chip in place as we will be destroying the board regardless, I am thinking of cutting the chip out from the board so it will sit flat on its back and some sort of adhesive to hold it down.

You mentioned about being able to CNC it within budget, would this be with the chinese cnc machines found on ebay?

Thanks for the reply.

[A_Camera]

This is the attitude that I like to hear! I have discussed a hand mill with colleagues and due to the parameters that we would have to work with wouldn't be an option, nobody here would trust themselves eyeballing the depth going through the PCB.

As for holding the chip in place as we will be destroying the board regardless, I am thinking of cutting the chip out from the board so it will sit flat on its back and some sort of adhesive to hold it down.

You mentioned about being able to CNC it within budget, would this be with the chinese cnc machines found on ebay?

Thanks for the reply.

Grate! Good luck.

[magicniner]

Grate! Good luck.

Sound advice as always :D

[m_c]

Trying it manually first would be my suggestion as well.

The hardest part will be finding the balance between mounting the chip/pcb securely, and how much of a cut you can take without the chip/pcb moving. I'm sure you don't need anybody to mention that you'll most likely want to experiment on some already scrapped items.

The only benefit you'll get from CNC is being able to set it up and leave it to do the bulk of the work, as you'll most likely need to adjust the depth slightly to get within the required tolerances for the final cut(s).

To go with Nick's conversion kit suggestion above, I'm sure I came across a german supplier of kits a while back, but my google skills are failing to find anything. They did however turn up this Danish supplier kit - http://cnchobby.dk/en/cnc-machines/4...0-cnc-kit.html

[PEU]

Thank you very much, I will be speaking with my supervisor about getting the manual machine ordered with some callipers!

[PaisleyPCdoctor]

I work with PCB'S and BGA's every day and I don't see why it wouldn't work. Biggest risk is ripping a solder ball off along with the on chip BGA pad. Slow plunge and a bit of care and it should be OK.

As for Chinese CNC not being up to it? What? Of course they would! It's just milling a bit of pcb and copper.

In fact- why do you need a CNC at all? For 10% of your budget you could get a basic manual mill/drill press. With micrometer depth adjustment, just step down, move it around xy axes, then down a bit more. Again- you don't need cnc for this- basically you just need control of the z (plunge) depth.

Want me to remove a BGA through the PCB? I can post a video to let you see how it goes.
I use a China 6040 that I've owned for 2 weeks and I KNOW it can be easily done.

Edit... Obviously the pcb will be destroyed, but as I understand it- you just want to salvage the usable chip, right?

[magicniner]

This is the attitude that I like to hear! I have discussed a hand mill with colleagues and due to the parameters that we would have to work with wouldn't be an option, nobody here would trust themselves eyeballing the depth going through the PCB.

You don't eyeball, you fit a DRO to the Z axis (digital caliper bodged on is popular) and measure the PCB thickness, set zero for the lower surface and you're good to go for precision depth milling ;-)

You mentioned about being able to CNC it within budget, would this be with the chinese cnc machines found on ebay?

Crikey No! They're Shite! If the Proxxon does the job manually just add steppers, drivers etc.
To cut down on leg work you could look for something like -

http://www.robotpark.com/Robotpark-MF-70-CNC-Kit

Not saying that one is any good but read reviews and Google around a bit and preferably find a supplier you can visit if things are going particularly Pete Tong ;-)

ATB,
Nick

[cropwell]

You don't eyeball, you fit a DRO to the Z axis (digital caliper bodged on is popular) and measure the PCB thickness, set zero for the lower surface and you're good to go for precision depth milling ;-)



Crikey No! They're Shite! If the Proxxon does the job manually just add steppers, drivers etc.
To cut down on leg work you could look for something like -

http://www.robotpark.com/Robotpark-MF-70-CNC-Kit

Not saying that one is any good but read reviews and Google around a bit and preferably find a supplier you can visit if things are going particularly Pete Tong ;-)

ATB,
Nick

Good grief ! that's cheap.