I have 0% experience in P&P machines and PCB manufacturing so sorry if that is a basic question.
I am curious if such a machine can be driven in a closed-loop fashion, that is if the operations it executes can process a more sophisticated data at its inputs at run-time. I also understand it is actually a computer that controls it - I just want to know how the method I presented is named in the industry..
I do not know the terminology of P&P either, so correct my vocabulary if I use funny names :)
I understand that whenever P&P sucks an element from the reel and it happens the element is missing (it senses "nothing sucked"), then it shifts this reel to the next element and picks that one. That is a simple example of interaction, when the action is made in the closed-loop.
Lets suppose I need to build a ~0,1% resistor voltage divider in the circuit (current flow is not that important).
One way to achieve such accuracy is to buy a highly precise resistors (rather expensive). I buy two reels of these and job is done.
As an alternative I could mount R>2 reels of less precise resistors selected so that at any possible combination of actual resistor values their respective resistance relation gives a required 0,1% accuracy of voltage divider. The problem is I need to collect the data to make it in a closed loop so lets suppose the head of the machine attaches a precision ohm-meter to a (N+1)th resistor whenever it picks Nth one from the reel. That way I have all the information about coming resistors on all R reels, the only thing I need is to make a decision on-the-fly which resistor pair to pick and place.
It does not seem to be a complicated decision but many factors can be involved. Obviously the higher R is, the less precise resistors I can buy, still getting the same effect of 0,1% divider. The whole synthesis can/should be covered using a probabilistic theory so that for example in 1 case per 1000 a resistor will have to be thrown away because it does not match the proportions. Digging deeper, a mean and variance values of resistors form Rth reel can be estimated to further improve the gain etc.
Does anybody know if such method can be used to reduce the BOM cost? Does it have a name?