Pin to Hole ratio is important in Intrusive Reflow.
The attached shows Pin to hole ratio ranging from .52 to .69 for .063" thick board. .63 and .69 give acceptable results while .52 and .56 leaves some voiding.
Same pin to hole seem to apply for .093 thick board. Sorry can't help with .150" thick board.
https://www.circuitnet.com/experts/uploads/1/hole_ratio.jpg
Bill Coleman
Vice President Technology, Photo Stencil
For over 18 years, Dr. Coleman has been the vice president of technology for Photo Stencil, working closely with customers to understand their printing requirements. His efforts have resulted in several new stencil products.
Aspect ratio is the ratio between the minimum hole diameter and overall thickness of the board.
For example; if the board thickness is 1.60mm and the minimum hole size is 0.40mm, then the aspect ratio is said to be 1:4 according to IPC, however when you change to a ticker PCB like you are, you will want to start reduce this aspect ratio, if the product is laid out for wave solder, as you will experience hole fill issues with this Aspect ratio.
In most cases you should not go below the aspect ratio 1:15. Higher aspect ratios are more difficult to produce at PCB fabrication.You can refer to the attached images of a PCB DFM guidelines.
https://www.circuitnet.com/experts/uploads/1/hole_diameter.jpg
Kishan Sarjoo
Process Engineering Manager - Electronics, Altech UEC, South Africa
Currently with Altech UEC and responsible for technology road map in PCBA electronic manufacturing and technical support for PCBA electronic manufacturing for Altech UEC and its JDM's. Over 7 years in SMT, Radial Insertion, Wave solder & Test Applications.
Many manufacturers have the capability of producing boards with a via aspect ratio of 10:1. If we apply this specification to your .150" board, the smallest through-hole diameter should be .015 inches. Your board shop should be able to provide more information on your design.
Edithel Marietti
Senior Manufacturing Engineer, Northrop Grumman
Edithel is a chemical engineer with 20 year experience in manufacturing & process development for electronic contract manufacturers in US as well as some major OEM's. Involved in SMT, Reflow, Wave and other assembly operations entailing conformal coating and robotics.
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