AREA CONSORTIUM PROCESS MANUALS

Lead-Free Assembly Process Manual
Author: Michael Meilunas

Description: This document provides material requirements, inspection guidelines and process recommendations for Pb-free area array assembly based upon our consortium sponsored research which covered a range of laminate and flex based BGAs and CSPs with pitches down to 0.5mm including Wafer Level CSPs (WL-CSPs). Much of the following is also relevant to other components such as ceramic BGAs and 0.4mm pitch WL-CSPs, except that the latter may be assembled without the use of solder paste. Very different considerations apply to flip chip and MLF/QFN/LGA assembly for which separate process guides are provided.

Assembly cannot be viewed independently of quality and reliability requirements and this document offers critical comments and recommendations pertaining to thermal cycle testing.

Lead Free Thermal Cycling:
Accounting for the Dwell Time Dependence in Thermal Cycling of Lead Free Solder
Solder Joint Strain Evolution during Thermal Cycling
Thermal Cycle Reliability Assessment of Surface Mount Devices

Lead Free Isothermal Cycling Test Protocols and Recommendations:
Damage Accumulation in Pb-Free Solder Joints for Complex Loading Histories
Effects of Variable Amplitude Loading on Lead Free Solder Joint Properties and Damage Accumulation

Pad Cratering:
Pad Cratering Overview
Test Methods for Evaluating Printed Circuit Board Pad Integrity
Pad Cratering in Drop Test: Solder Alloy Effect
Investigation of Crack Propagation in Pad Cratering Failures
Comparison of Joint Level Test Methods for PCB Pad Cratering Investigations
Pad Cratering: Characterizing Crack Propagation and the Effects of Humidity and Reflow on Reliability
Effects of Pre-stressing on Solder Joint Failure by Pad Cratering
The Effect of Partial Pad Craters on Drop/Shock Reliability
Effects of “Latent Damage” on Pad Cratering: Reduction in Life and a Potential Change in Failure Mode
Methodology for Assessing the Reliability Impact of Partial Pad Craters

Pad Finish Defects:
An Overview of Printed Circuit Board Pad Finishes
Assembly of LF-2 Bumped Chips on Silver and Tin Pad Finishes
Voids in Cu3Sn: Copper Screening Recommendations
On the Root Cause of Kirkendall Voiding in Cu3Sn

Backward Compatible Assembly and Reliability:
Mixed Alloy Process Manual
Backward Compatible Fine Pitch CSP Build and Thermal Cycling With and Without Underfill (0.4mm & 0.5mm)
Mixed Solder Alloy Reliability
Effects of Solder Paste Volume and Reflow Profiles on the Thermal Cycling Performance of Mixed SnAgCu/SnPb Solder Joints
Effects of Cycling Parameters on the Thermal Fatigue Life of Mixed SnAgCu/SnPb Solder Joints

PoP:
Package on Package (PoP) Assemblies: Underfilling and Mechanical Robustness
Assembly Study of 0.4/0.5mm Pitch Through-Molded-Via (TMV) Package on Package (PoP)

PCB Materials:
Effect of Laminate Material Selection on Pad Level and Board Level Drop Reliability
Comparisons of PCB Pad Definitions on Drop Test Reliability
Lead-Free Printed Circuit Board Process Manual: Version 2007

QFN/MLF Assembly and Reliability:
QFN/MLF Process Guide: A ‘Cookbook’ for Optimizing Assembly Yield and Reliability
QFN/MLF Process Guide

Component Underfilling and Testing:
Underfill Process Codification – A Step-By-Step Guide
Component Underfill Manual

Lead Free Rework and Repair:
AREA Consortium Rework Process Manual – Version 2014

Update Submitted by: Harry Schoeller
Added to this version:

• Rework of Fine Pitch Components:

  • Rework and Re-ball process for 0.3mm CSP

  • Reliability of Reworked assemblies in ATC and drop testing

• Vapor Phase Rework:

  • Description of VP desoldering fixture

  • VP desoldering procedure

Flip Chip Assembly & Reliability:
Pad Design Guidelines for Direct Chip Attach Assembly
Flip Chip Assembly Manual

Flip Chip Underfilling:
Flip Chip Underfill Process Manual

No-Flow Assembly:
Reflow Encapsulant/No-Flow Underfill Manual

TIM:
Process Induced Defects in Thermal Interface Assembly
Maintaining Thermal Bond Line Performance Following Formation: Cure or Secure
Bondline Assembly Process Manual

0.4mm Pitch Reliability:
Print Volume Influence on Mechanical Test Performance of 0.4mm Pitch CSPs and LGAs