BerkeleyUNIVERSITY OF CALIFORNIA /

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l: Drilling Burr Minimization and Energy Saving for PCB Production

Yu-C

hu H

uang

yu

chu@

berk

eley

.edu

■  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.

Funding Sources: Korea Institute of Industrial Technology Motivation

■  The general goal of the project is to develop a energy-saving manufacturing process for information technology (IT).

■  The research consortium:

Information Flow Diagram

Background Energy Saving

Experiment Setup

Types of Drilling Burr

Drilling Burr Control Chart

Future Work

■  What is a printed circuit board (PCB)?

■  Energy flow in PCB drilling machine

■  To achieve energy saving, our strategy are: - Minimizing the size of drilling burrs - Reducing tool wear - Reducing PCB drilling lead time

■  Process parameters •  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

■  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.

■  Based on the definition, we aim to develop the Drilling Burr control chart (DBCC) for PCB by varying the drilling conditions.

■  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 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.

■  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 Type 2 Type 3

PCB

PCB

Epoxy

Entry board

Backup board

Cu

GFRP Cu

PCB

Bakelite PCB

Drilling stack

Resist Strip

Copper Etch

Resist Develop

UV Exposure

Photoresist Coating Pro-clean

Photoresist Coating

Electroless Copper

Deburr and Scrub

Hole Desmear

Hole Drilling

Laminate inner

Layers

Oxide Treatment

Pattern Plate

Copper

Pattern Plate Etch

Resist

Resist Develop

UV Exposure

Photoresist Strip

Etch Resist Strip

Copper Etch

Solder Mark

Application

Final Fabrication

Nickel Gold

Plating

Hot Air Solder Level

Process

Circuit Design

Outer Layer Image Transfer

Inter Layer Image Transfer

Surface Finish

Accelerometer

Dynamometer

Spindle

f400 mm

- What we are focusing on

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.

Energy input for the drilling machine Energy transferred

to final product

Energy lost due to friction

Energy lost due to electrical motor Energy lost at heating step

- What we are focusing on

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.

n  Common drilling tool

New bit

X 500

After 790th hit

X 500

Drilling experiment setup

The process flow diagram for manufacturing PCB

Material: Aluminum alloy

Information exchanged with SNU

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

Demo Site2 KOFCO

Energy lost due to standby mode