FCBGA Package Warpage ØII

Definition Stage Project

Kirk Van Dreel, Plexus

HDP User Group Member MeetingHost: EngentAtlanta, Ga.

September 9, 2015

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BackgroundPackage/board Warpage increasing trends

•Driven by thinner package substrates and thinner die  Package/Board contacts getting smaller and closer

thereby reducing ability to overcome increased Warpage.  Solder Joint Quality is Impacted by the increasing

Package Warpage.

With advent of lead free soldering, the assembly temperatures have increased and the Warpage impact has been exacerbated.

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Goal

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Establish a limit for dynamic package warpage that can be mitigated during board assembly without impacting solder joint quality

Project Objectives

Phase 1 - Test Method DevelopmentThis phase will establish a test method which will enable the team to compare and contrast the effects of the mitigation techniques.

Phase 2 - Characterization Of Mitigation Methods and Max Package Warp Specifications

This phase will leverage phase 1’s output to establish the maximum warp an optimized process can accommodate and characterize the contribution of the mitigation techniques on the process yield.

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Hot Air Rework Machine Method

Basic Concept of Hot Air Rework Equipment and Process Blowing heated air from the top, down on to the BGA package using a

nozzle The air heats up the package, board and solder joints Air temperature and flow rate is controlled Package is lifted up or down with a vacuum cup Video Camera, can record a few solder joints on the outside row on one

side of the package The basic concept is to lift the component up or down at different

temperatures to simulate dynamic warpage characteristics of the package

Rework Machine SRT Summit 1800

Video camera

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Test Vehicle

Factor LowerPCBA Materials

Size 155 X 60 mmThicness 0.63inSurface Finish ENIGSolder Mask Tayo 4000Pad Size 0.60mmSolder Mask Opening 0.40mmSubstrate Mtrls 370HRCu Weight 1/2 oz CuLayer Count 2

ComponentsSize 10.6mm sqI/O Count 28Thickness 0.063inSolder Alloy SAC305Surface Finish ENIGSolder Mask Tayo 4000Substrate Mtrls 370HRCu Weight 1/2 oz CuLayer Count 2Ball size 0.55mmPad size 0.5Pitch 1.2 mm

Phase II: Test Plan

Factor Lower UpperSolder Materials

Solder Paste Activity L0 H1Solder Paste Tackiness 30gr 50gr

Reflow Profile    Cooling rates (Delta T) 10C/sec 30C/secPeak temperatures 2350C 2550CAtmosphere PPM Air 500 ppm

Stencil    Stencil Thickness 3.5 mil 5.0 milSolder paste volume 120% of 3.5mil  70% of 5 mil

Factors:

Phase II: Test Plan

Category Response Criteria Measurement Tool

Z-axis Displacement to products

As Placed +/- 12 um flatness Camera Pixel Count

Pre-Liquidus + 12 um above paste Camera Pixel Count

Peak Reflow + 12 um above paste Camera Pixel Count

Failure Rate HoP DPMO 

Defect per solder joint Visual Inspection / Die & Pry, Sample X-ray CT

NWO DPMO Defect per solder joint Visual Inspection / Die & Pry, Sample X-ray CT

Responses:Primary Response:

Sample Size:Total Substrates: 620Total Components: 620 8

Phase II Project Activities

Project Activities ProviderFinalize Protocol Team

Provide Laminate for Substrates Panasonic

Fabricate Substrates Sanmina

Substrate Bumping Nihon-Superior

Rework System Programming VJ Technologies*

Stencil Procurement Nihon Superior

Lease Printer HDP

Assemble Substrates Plexus

Die and Pry Analysis Engent

Plexus

Sanmina-Huntsville

Nihon-Superior

VJ Technologies*

Cross Section Analysis Plexus

Data Analysis Plexus

Report Development Team

* Non-Member

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Phase II Proposed Schedule

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Project Plan Owner Est. CompActual

Test Vehicle Design Plexus 08/01/2015 07/16/2015Finalize Protocol TEAM 10/01/2015Substrates FabricationSanmina 10/30/2015 Lease Screener ($8.6K) HDPUG 11/03/2015Order Stencils Nihon-Superior 10/23/2015Rec’v Substrates VJT 11/02/2015Rec’v Stencils Nihon-Superior 10/30/2015Component Bumping Nihon-Sup’r/Micross 10/30/2015Receive Screener HDPUG/VJT 11/06/2015Rework System Programming VJT 11/02/2015Complete Test Vehicles ASM VJT 12/21/2015Die and Pry Analysis Plexus,VJT,Sanmina,

Nihon-Sup’r, et al 02/19/2016Complete Data Analysis Plexus 02/19/2016Sample X-Ray AnalysisPlexus, VJT 04/04/2016Write Report TEAM 05/29/2016

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Team Members

• Akrometrix

• Alcatel-Lucent

• Arlon

• Celestica

• Cisco

• Curtiss-Wright

• Engent

• Ericsson

• Flextronics

• Freescale

• Fujitsu

• Hitachi-Chemical

• Huawei

• IBM

• Indium

• Isola

• Juniper

• Keysight

• Kyzen

• Multek

• Nihon-Superior

• NVIDIA

• Oracle

• Panasonic

• Philips

• Plexus - Team Leader

• Sanmina

• TTM Tech

• Viasystems

• VJ Technologies (Non-Member)