What is the best aperture geometry for depositing paste on round ball grid array pads on PCB’s. To find the answer we need to rephrase the question. For the same volume of paste deposit what is the best shape which gives the largest clearance between the deposits. For stencil of thickness “s” a round aperture with diameter of “d” will deposit (3.14*(d/2)^2*s )=0.78*d^2*s paste by volume. To have same volume of paste from a square aperture the size of the sides of the square need to be 0.88*d. So choosing a square aperture will give us better clearance between deposits as with square aperture the clearance will be increased by 0.12*d
Hooman attended University of Toronto for electrical engineering, and received his bachelor of commerce from Ryerson in Information Technology. For over 10 years, Hooman has been a leader in electronic manufacturing services helping clients from with various assemblies of PCBs and prototype designs.