Improved Process Yield with Dynamic “real-time” Dual Head Dispensing
Today’s unique assembly challenges are comprised of complex PCB panelization, involving identical PCBs with a goal towards increased production capability, due to a reduced footprint of the Production Floor. Identical PCBs that are within the same panel, with uniform spacing in an array or carrier, need to be dispensed at the same time. All these high-mix challenges have gone mainstream and affects the real productivity and throughput. Existing manual dual head dispensing systems do not consider the rotational correction for the second head, which leads to yield loss. To eliminate the yield loss on second head, there is a mini XY drive system incorporated that provides fast and accurate dispensing to double the process capabilities over the same work area. Dynamic dual head dispensing uses a unique mini XY drive system on left head, mounted on a separate Z-axis, to dynamically control the position of the second head for accurately aligning to a second part, while synchronously dispensing both parts. Machine vision system performs the substrate alignment for each identical PCBs that are individually placed in a carrier, which provides greater potential for variation in offset and skew. During synchronous dispensing for the second part with the DDH, all the kinematic adjustment is performed with calculated values, from the skew angle and scaling factor. This technique guarantees increased productivity whilst maintaining yields through unsurpassed accuracy. DDH also provides the same level of adjustment and rotational correction for all step and repeated PCB’s, flex circuits and panel designs. If product contains odd number of units then either of the head can be programmed for dispensing while the others can’t.
This paper examines proven methods to determine the dot/line positional accuracy along with mass flow rate for both heads during synchronous dispensing. This paper will also address the challenges faced, and how the rotational correction can achieve up to 2X higher dispense productivity then existing single/dual head dispensing systems.