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


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


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