Building a cheap ACF tape bonding machine
Now that ACF tape is available to buy and doesn't cost an arm and a leg (it's still pricey, but 50m of tape for $80-something sounds fair to me, considering the size of a tab), i have decided to build my own bonding machine.
The few builds i have seen use a commercial bonding head and that costs $3000 to $5000 - OUCH. I was thinking more like $50.
I have read the datasheet for the Hitachi ACF tape and it occurs to me that the requirements are not very stringent - the tape should reach 160 to 180C for 20 to 30 seconds, at a certain pressure applied by the bonding head. A suggested temperature (305C) for the bonding head is also given in the datasheet, and the only requirement for the head's shape is that it must have an even surface where it presses down on the tab (duh). There are no slopes required as it is with soldering BGAs, temperature just needs to get up there as fast as possible, stick there for 30 seconds then cool down. So the design of the control circuit is also easier.
I have already chosen my heating element (it's a surprise, you'll laugh) and completed the design of the control circuit - all that's left is making the PCB. There is no microcontroller and no firmware involved, it's all analog.
The output drives a relay so any kind of heating element can be used, and the input is a normal type K thermocouple. Control is accomplished via a couple pots and switches. The circuit turns the heater completely off once the time set has elapsed, and can also run a fan if desired.
Anyone else interested?
The few builds i have seen use a commercial bonding head and that costs $3000 to $5000 - OUCH. I was thinking more like $50.
I have read the datasheet for the Hitachi ACF tape and it occurs to me that the requirements are not very stringent - the tape should reach 160 to 180C for 20 to 30 seconds, at a certain pressure applied by the bonding head. A suggested temperature (305C) for the bonding head is also given in the datasheet, and the only requirement for the head's shape is that it must have an even surface where it presses down on the tab (duh). There are no slopes required as it is with soldering BGAs, temperature just needs to get up there as fast as possible, stick there for 30 seconds then cool down. So the design of the control circuit is also easier.
I have already chosen my heating element (it's a surprise, you'll laugh) and completed the design of the control circuit - all that's left is making the PCB. There is no microcontroller and no firmware involved, it's all analog.
The output drives a relay so any kind of heating element can be used, and the input is a normal type K thermocouple. Control is accomplished via a couple pots and switches. The circuit turns the heater completely off once the time set has elapsed, and can also run a fan if desired.Anyone else interested?
A few high brightness LEDs should do for light source.
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