Cleaning Medical Electronics MIKE BIXENMAN KYZEN CORPORATION MARK NORTHRUP DYNAMIC RESEARCH TESTING LAB DALE LEE PLEXUS CORPORATION 9/18/2012 2012, Kyzen Corp. 1
Discussion Points 1. Introduction 2. Design for Cleaning 3. Test Vehicles 1. Solder Mask Definition 2. Voltage Effects 3. Frequency Effects 4. Conclusions 9/18/2012 2012, Kyzen Corp. 2
Medical Electronics The challenge for Medical OEMs is to Design reliable electronic hardware Performs reliably for the patient Implantable devices require Increased functionality Small form factor Fast data transfer 9/18/2012 2012, Kyzen Corp. 3
Patient Information on Demand Trends lead to Electronic component complexity Require faster signal rates Higher transmission frequencies The concern is that Hardware failures will become more prevalent 9/18/2012 2012, Kyzen Corp. 4
Reliability Reliability concerns challenge OEMs to Look outside the existing design rules Toward application specific field simulations Better understanding of reliability risks 9/18/2012 2012, Kyzen Corp. 5
Circuit Board Design Plays a role when cleaning is required Component size / standoff height Solder mask definition Solder paste selection Package placement / density Thermal heat to solder components Static solvating rate Dynamic energy rate 9/18/2012 2012, Kyzen Corp. 6
Test Vehicles 1. Designed to test removal of soils Z-Axis gap height Density Placement 2. Designed to test electrical effects Voltage effects Frequency effects 9/18/2012 2012, Kyzen Corp. 7
Clean Test Board 9/18/2012 2012, Kyzen Corp. 8
Solder Mask Options 9/18/2012 2012, Kyzen Corp. 9
Miniaturization Continues 01005 chip cap 0.4mm x 0.2mm Murata introduces new chip capacitor 0.25mm x 0.125mm 9/18/2012 2012, Kyzen Corp. 10
Smaller Components Tighter standoff heights Capillary forces pull flux under component 9/18/2012 2012, Kyzen Corp. 11
Solder Mask Defined Solder mask defined pads Solder mask between pads 9/18/2012 2012, Kyzen Corp. 12
Non Solder Mask Defined Solder mask removed adjacent pads Solder mask between pads 9/18/2012 2012, Kyzen Corp. 13
No Solder Mask Solder mask removed adjacent pads No Solder mask between pads 9/18/2012 2012, Kyzen Corp. 14
SMD 0201 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 15
NSMD 0201 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 16
No Solder Mask 0201 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 17
SMD 0402 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 18
NSMD 0402 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 19
No Solder Mask 0402 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 20
SMD 0805 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 21
NSMD 0805 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 22
No Solder Mask 0805 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 23
SMD 1210 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 24
NSMD 1210 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 25
No Solder Mask 1210 Chip Caps Before Cleaning 9/18/2012 2012, Kyzen Corp. 26
SMD (QFN/MLF) Before Cleaning 9/18/2012 2012, Kyzen Corp. 27
NSMD (QFN / MLF) Before Cleaning 9/18/2012 2012, Kyzen Corp. 28
No Solder Mask (QFN / MLF) Before Cleaning 9/18/2012 2012, Kyzen Corp. 29
Solder Mask Defined PBGA Before Cleaning Wide Pitch Narrow Pitch 9/18/2012 2012, Kyzen Corp. 30
Non Solder Mask Defined PBGA Before Cleaning Wide Pitch Narrow Pitch 9/18/2012 2012, Kyzen Corp. 31
No Solder Mask (PGBA) Before Cleaning Wide Pitch Narrow Pitch 9/18/2012 2012, Kyzen Corp. 32
Data Findings 9/18/2012 2012, Kyzen Corp. 33
Chip Caps Main Effects Plot for % Residue under Chip Caps Component Data Means Component Wash Time (min.) 40 30 20 10 Mean 0 0201 0402 0805 1210 Solder Mask Definition 1825 1 5 40 30 20 10 0 NoSM NSMD SMD 9/18/2012 2012, Kyzen Corp. 34
Ball Grid Arrays Main Effects Plot for % Residue under BGA Components Data Means Component Wash Time (min.) 10.0 7.5 5.0 2.5 Mean 0.0 BGA360 PBGA324 PBGA676 Solder Mask Definition 1 5 10.0 7.5 5.0 2.5 0.0 NoSM NSMD SMD 9/18/2012 2012, Kyzen Corp. 35
MLF / QFN Main Effects Plot for % Residue under QFN Component Data Means Component Wash Time (min.) 90 80 70 60 Mean 50 MLF88 Solder Mask Definition 1 5 90 80 70 60 50 NoSM NSMD SMD 9/18/2012 2012, Kyzen Corp. 36
All Component Types Main Effects Plot for % Residue under Component Data Means 80 Component Wash Time (min.) 60 40 20 0 Mean 0201 0402 0805 1210 1825 BGA360 MLF88 PBGA324 PBGA676 1 5 80 Solder Mask Definition 60 40 20 0 NoSM NSMD SMD 9/18/2012 2012, Kyzen Corp. 37
Voltage Effects 9/18/2012 2012, Kyzen Corp. 38
Circuit Designs SMT QFN BGA 9/18/2012 2012, Kyzen Corp. 39
Test Patterns Donut Cross X 9/18/2012 2012, Kyzen Corp. 40
Electrical Field Miniaturization Lower contamination levels Less metal is dissolved With less metal ions levels Electrical field drives metallic ion forces The electric field will be higher As distance between conductors reduce Minzari et al., 2009 41 2012, 9/18/2012 Kyzen Corp.
Constant Voltage Rises inversely with conductor spacing Traces as small as 48µm (1.98 mils) At 5V ~ electric field = 2.5V At 0.4V/mil to 1.6 V/mil the occurrence of dendrites increased Bumiler & Hillman (2010) 42 2012, 9/18/2012 Kyzen Corp.
Halogen Ions 25 mil comb spacing Withstand higher levels of contamination >20 µg/in 2 12.5 mil comb spacing Levels at 5-20 µg/in 2 problematic 6 mil comb spacing Levels of 0-2 µg/in 2 problematic Bumiler & Hillman (2010) 9/18/2012 2012, Kyzen Corp. 43
Electrical Field High Voltage Data 9/18/2012 2012, Kyzen Corp. 44
Frequency 9/18/2012 2012, Kyzen Corp. 45
Controlled Loss Testing Controlled loss testing involves Dissipation factor (Df) of the PCB material Copper surface roughness Uniformity of the PCB conductor etched features Conductor length and impedance mismatches PCB surface finish, solder mask etc. 9/18/2012 2012, Kyzen Corp. 46
Insertion Loss The PCB alone involves four components of insertion loss which include Dielectric Conductor Leakage and Radiation 9/18/2012 2012, Kyzen Corp. 47
Current Cleanliness Testing Protocol IPC TM 650 Method 2.3.28 Ion Chromatography 75% IPA / 25% DI water 60 minute extraction period Ineffective for High Frequency Foresite C3 Localized extraction Steam extraction using DI water 3 minute extraction period Limited application Progression of Methods IPC 2.3.28 (Global) Foresite C3 (Isolated)? New Method (Tighter isolation) 9/18/2012 2012, Kyzen Corp. 48
Research in Progress Correlate chemical with electrical effects Correlate Ionics on a test board to failure with different frequency levels 1 GHz 10 GHz 20 GHz 40 GHz Set limits that an engineer can use to predict failure and control a process 9/18/2012 2012, Kyzen Corp. 49
Test Vehicle Test from 1, 10, 20, 40 Giga Hertz Measure interactions What do we measure Parasitic Capacitance Controlled Impedance Controlled Inductance Frequency Shift Gain or Loss Phase Shift or Change Scattering(S) Parameters 9/18/2012 2012, Kyzen Corp. 50
Proposed Test Vehicle Structures 9/18/2012 2012, Kyzen Corp. 51
Loss Data Example 9/18/2012 2012, Kyzen Corp. 52
Concluding Remarks 9/18/2012 2012, Kyzen Corp. 53
Circuit Board Design Capillary flux action underfills tight gaps Chip caps and QFN devices Removal of solder mask reduces Flux residue under component Increases gap height Easier to clean BGA components Solder mask defined pads were easier to clean NSMD were slightly more difficult to clean over SMD No Solder Mask increased cleaning difficulty 9/18/2012 2012, Kyzen Corp. 54
Voltage Tighter pitch devices Increases electrical field Less contamination more problematic Lower levels of contamination critical factor 9/18/2012 2012, Kyzen Corp. 55
Frequency High Frequency More problematic to failure New test method needed to Quantify ionic contamination with electrical Guideline for engineers to know limits for specific voltage, frequency and currents 9/18/2012 2012, Kyzen Corp. 56
Thank You
Authors Mike Bixenman Chief Technology Office Kyzen Corporation mikeb@kyzen.com Mark Northrup Director of Advanced Technical Operations Dynamic Research Testing Labs (IEC Electronics) mnorthru@iec-electronics.com Dale Lee Staff DFX Project Engineer Plexus Corporation dale.lee@plexus.com 9/18/2012 2012, Kyzen Corp. 58