1. technology and computing
2. electronic components

Drilling Burr Minimization and Energy Saving
for PCB Production
Funding Sources: Korea Institute of Industrial Technology
Yu-Chu Huang © 2011 LMAS
contact email: yuchu@berkeley.edu
Motivation
Information Flow Diagram
■  The hole drilling step is important in the manufacturing of
Printed Circuit Boards (PCB). It influences the shape of burrs
and the deburring process. Minimizing drilling burr can reduce
effort and time for deburring, and therefore decrease energy
consumption for the whole process.
Inter Layer Image Transfer
Circuit
Design
Photoresist
Coating
Pro-clean
Photoresist
Coating
UV
Exposure
Resist
Develop
Copper
Etch
Resist
Strip
Electroless
Copper
Deburr and
Scrub
Hole
Desmear
Hole
Drilling
Laminate
inner
Layers
Oxide
Treatment
Resist
Develop
UV
Exposure
Pattern
Plate
Copper
Pattern
Plate Etch
Resist
Photoresist
Strip
Copper
Etch
Etch Resist
Strip
Final
Fabrication
Nickel
Gold
Plating
Hot Air
Solder
Level
Process
Solder
Mark
Application
Outer Layer Image Transfer
- What we are focusing on
The process flow diagram for manufacturing PCB
■  The general goal of the project is to develop a energy-saving
manufacturing process for information technology (IT).
■  The research consortium:
Design Tech for PCB
Process
SNU/UCB
Optimization and Fusion
Process Tech for Forging
U of Ulsan/U of Hannover
Quality Management,
Simulation and
Process Optimization
KITECH/CAU
Quantification and
Optimization Based on
LCA
KAIST/NIST PMU Diagram and Configurable EMS
KITECH/U-Bot INC
PMU Diagram and Configurable EMS
KITECH/U-Bot INC
Demo Site1
BM Korea Co., Ltd
Information exchanged with SNU
Surface Finish
Background
Energy Saving
■  What is a printed circuit board (PCB)? n  Common drilling tool
■  Energy flow in PCB drilling machine
f400 mm
PCB
- What we are focusing on
Energy lost at heating step
Energy lost due to electrical motor
Drilling stack
Cu
Entry board
GFRP
Demo Site2
KOFCO
Cu
Energy lost due to standby mode
Energy lost due to friction
Bakelite PCB
Energy input for the
drilling machine
PCB
Epoxy
Energy transferred
to final product
Backup board
PCB
n  The importance of PCB drilling process
The global market size of PCB products in 2009 was $44.4 billion and
is projected to register about $76.2 billion by the year 2015. If we can
reduce the energy consumption in PCB drilling process, the global PCB
market and our environment will be benefited.
Experiment Setup
Types of Drilling Burr
■  Process parameters
Accelerometer
•  Bit diameter:
400µm
•  Spindle speed: 90000 rpm
•  In-feed speed: 40 mm/sec
•  Hits:
790 hits (2000hits)
•  Sampling frequency: 20 kHz (low 9 kHz)
•  Sampling time: 5 sec (x3)
•  Sensors:
3-axis dynamometer,
3-axis accelerometer
•  Stacks:
3 layer (recommended by Axis)
•  Entry board:
Al
•  Backup board: wood
■  Tool wear in PCB drilling
X 500
New bit
■  To achieve energy saving, our strategy are:
- Minimizing the size of drilling burrs
- Reducing tool wear
- Reducing PCB drilling lead time
Spindle
■  Three types of drilling burr were defined
Type I – uniform burr with smaller burr height.
Type II – uniform burr but with a relatively large burr height.
Type III – crown burr which has no drill cap.
Material:
Aluminum alloy
Dynamometer
Drilling experiment setup
X 500
After 790th hit
Drilling Burr Control Chart
■  A DBCC is proposed as a tool to assist prediction and control
of drilling burr under given drilling conditions.
■  Here is an example for one material and driller combination.
Type 1
Type 2
Type 3
■  Based on the definition, we aim to develop the Drilling Burr
control chart (DBCC) for
PCB by varying the drilling
conditions.
Picture Source: Kim J, Min S, Dornfeld D (2001) Optimization and Control of Drilling Burr Formation of AISI 304L and AISI 4118 Based on
Drilling Burr Control Charts. International Journal of Machine Tools & Manufacture 41(7):923–936.
Future Work
■  Developing the drilling burr control chart for PCB
■  Analyzing relationships among process parameters and energy
■  Reducing PCB drilling lead time
■  Constructing energy saving knowledge
■  Increasing the energy efficiency for drilling
■  Constructing information database of PCB drilling
■  Type 1 burr is smallest and preferred. To minimize the drilling
burr, the rectangle points out the generally recommended
ranges of cutting parameters.
Picture Source: Min S, Kim J, Dornfeld DA (2001) Development of a Drilling Burr Control Chart for Alloy Steel AISI 4118. Journal of Materials
Processing Technology 113(1–3):4–9.
Berkeley
/
UNIVERSITY OF CALIFORNIA