San Diego, CA High Density and High Speed Approach for Probe Card PCB Takashi Sugiyama Hitachi Chemical Co. Ltd.
Overview Technical trend for wafer level testing Requirement for high density and high speed application on PCB level Approach for Higher Density Approach for Higher Speed Summary IEEE SW Test Workshop 2
Technical trend for wafer level ltesting Capability for Higher Density and Higher Speed Device Lower cost and Shorter testing time ( Reduction in number of contact) IEEE SW Test Workshop 3
Requirement for PCB level High Density and Shorter testing time ; - Application of Fine line - Additional Signal layers High Speed ; - Application of Low signal resistance - Application of Low Dk, Df material Thickness limitation ; - PCB thickness must be less than 6.2mm normally Difficult for MLB (normal print and etch type PCB) What is a best solution????? IEEE SW Test Workshop 4
That is a MWB!! *MWB (Multiwire Board) is a PWB which replaces etched signal traces with insulated copper wires *Use of insulated copper wires greatly improves signal density IEEE SW Test Workshop 5
Features of MWB Features High density Wiring Key Technologies Insulated Wire (Cross over Wires) Low Signal resistance Smaller Propagation loss Low wire surface roughness Accurate Zo control Uniformity of Wire diameter Accurate timing control Own Design Software (MDS) IEEE SW Test Workshop 6
Mechanism of Wiring Ultrasonic transducer Ultrasonic Coil Ultrasonic Generator wire Adhesive sheet Wire Adhesive sheet Prepreg Base material Wiring machine table IEEE SW Test Workshop 7
Actual Wiring Operation IEEE SW Test Workshop 8
Wire structure and Electrical properties Conductor Wire (Cu) Structure Insulated Layer (Polyimide) Adhesive Layer Wire diameter mm 0.10 (+/-0.003) 0.08 (+/-0.003) 0.065 (+/-0.002) Insulation thickness mm 0.015 0.020 0.020 Adhesive thickness mm 0.014(0.013~0.017) Outer diameter mm 0.158 0.148 0.128 Electrical resistance ohm/m 2.15 3.5 5.3 Current Capacity A 0.7 0.5 0.3 Breakdown Voltage >3.0 >3.0 >3.0 kv (max. available value ) (12) (15) (12.8) *Using this data as a reference IEEE SW Test Workshop 9
MWB Process Flow Power/Gnd Layer Wiring i Layer Inner Layer Formation Inner Layer Formation Prepreg Lamination Adhesive Lamination Wiring Expansion of a joint Plating Outer Layer Formation Resist and Screen Printing External form processing Inspection Drilling Power/Gnd Layer and Wiring Layer Lamination IEEE SW Test Workshop 10
Approach for Higher Density IEEE SW Test Workshop 11
Key ypoint for Higher Density Signal Resistance for fine line formation Cross talk for narrow signal pitch Impedance control for additional signal layers ( distance between signal and Gnd) IEEE SW Test Workshop 12
Evaluation of Signal Resistance for MLB and MWB Sig gnal Res sistance e, Ω/240 0mm 5 4 3 2 1 MLB 0.5oz MLB 1oz MWB Target Range 0 (<1.5Ω) 0.04 0.06 0.08 0.10 0.12 0.14 0.16 Line width or Wire diameter, mm *Using this data as a reference IEEE SW Test Workshop 13
Evaluation of Cross-talk (Backward) for MLB and MWB 10 Backw ward Cro osstalk, % 8 6 4 2 0 MLB 0.09mm,1oz MWB Φ0.065 100 150 200 250 300 Line Pitch, mm [Condition] Material: Polyimide, L: 260mm, Z 0 :50Ω, Tr:35.5ps Target Range (<4%) *Using this data as a reference IEEE SW Test Workshop 14
Evaluation of Impedance for 0.065mm wire Unit : ohm Item Board-1 Board-2 TotalA ve W1 W2 W3 W5 W1 W2 W3 W5 Ave 52.30 50.62 52.19 50.66 51.88 50.30 51.83 50.69 51.31 Strip-line GND Example Reading range (20-40%) wire GND 50 ohm Note : - Evaluation PWB:MWB(Strip-Line) - Material: polyimide(i671) - Temperature & Humidity:25 /60% RH - Method: TDR *Using this data as a reference IEEE SW Test Workshop 15
2Lines/0.8mm Design Study for MLB and MWB 0.8 Dp Sp Sl Dh L Dh : Hole Dia. Dp : Pad Dia. L : Line width Sl : Space ( L-L ) Sp : Space ( P-L) Item Unit MLB(1) MLB(2) MWB Thickness mm 6.2 Drill Dia. mm 025 0.25 025 0.25 025 0.25 Pad Dia. mm 0.40 0.40 - Line width mm 0.090090 0.080080 0.065065 Space L-L mm 0.120 0.080 0.113 Space P-L mm 0.050 0.080 - Resistance Ω/m 5.5 7.0 5.3 Crosstalk % <5% 10% < <4% Comment NG NG OK MWB is suitable for both high density wiring and high electric performance IEEE SW Test Workshop *Using this data as a reference 16
Signal Capability study for MLB and MWB TH pitch Item MLB MWB Line/Pitch 1 2 0.8mm Signal/Layer 300 1000 Capable Net Count 9,000 (30 layers) 12,000 (12 layers) Line/Pitch 2 3 1.0mm Signal/Layer 400 1200 Capable 12,000 15,000 Net Count (30 layers) (12 layers) *Using this data as a reference IEEE SW Test Workshop 17
Signal capability study for MLB and MWB -2 MLB Layer=Wiring layer*2.5+ Power/Gnd Layer 100 90 Difficult Zone for MLB L90 L100 L110 # of Lay yer 80 70 MLB L76 L80 60 W60 W62 50 40 MWB W44 W42 Reference data Depend on # of Power layer & Signal Capacity 3000 6000 9000 12000 15000 18000 21000 24000 # of Net W50 *Using this data as a reference IEEE SW Test Workshop 18
Conclusion of Higher Density Approach Signal Density per layer of MWB is 2.5 times higher than MLB by using cross over wires MWB is also suitable for high electric performance MWB can reduce total # of layers or can use additional power layers by reducing signal layers comparing to MLB MWB has a potential capability for 23,000 nets IEEE SW Test Workshop 19
Approach for Higher Speed IEEE SW Test Workshop 20
Key point for Higher Speed Application of Low Dielectric (Dk, Df) material Low Conductor loss Elimination of Stub IEEE SW Test Workshop 21
LSI Signal Integrity LSI Attenuation 1. Dielectric Loss Dk, Df 2. Conductor Loss Re 3. TH capacitance, Stub C TH 22 Input C T H Z 0 50Ω Dk, Df Reflection Z 0 =50Ω Re C TH Z 0 50Ω Reflection Output Noise 1.Reflection due to impedance mismatching 2.Crosstalk between signal lines IEEE SW Test Workshop 22
Dielectric (Dk, Df) property for each Materials 0.0020 0.0040 Dk(1GHz) 4.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 0 Material A Material B 0.0060 High High-End Grade Df(1 1GHz) 0.0080 0.0100 0.01200120 0.0140 0.0160 Material D (Polyimide) Material C Middle-Range Grade 0.0180 0.0200 Material E (FR-4) 0.0220 0.0240 Standard Grade *Using this data as a reference IEEE SW Test Workshop 23
Key point for Low Conductor Loss Low Conductor surface roughness ( Minimize Skin Effect ) Constant Conductor width IEEE SW Test Workshop 24
Study of Conductor Width and Conductor Surface Roughness for MLB and MWB Constant Wire Diameter Small Roughness of Wire Surface MLB : Etched Cu MWB : Cu Wire Diamond die is used for Cu Wire 10um ±0.025mm ~10um Tolerance of Conductor Width Conductor Surface Roughness ±0.003mm ~0.5um IEEE SW Test Workshop 25
Signal Attenuation Simulation Attenuation = Dielectric Loss (Dk, Df) + ConductorLoss (Re) MLB 0.1mm,1oz MWB φ0.10 Material Conductor 0 1 2 33 4 5 6 7 8 Atten nuation@ @3GHz, m db/260m FR4 Middle Range High Frequency Polyimide Middle Range High Frequency Normal VLP HVLP Dielectric Loss Conductor Loss Conductor loss of MWB is much less than MLB s IEEE SW Test Workshop *Using this data as a reference 26
on@3gh Hz, db/26 60mm Attenuati Attenuation measurement result Frequency, GHz 0 1 2 3 4 5 6 0.0-2.0-3.6 36-4.0-4.4-6.0 60-8.0 MLB FR4 MLB Middle Range MLB High Frequency MWB Polyimide φ0.1 MWB Middle Range φ0.1 [Condition] MLB Line: 0.1mm/1oz, Z 0 :50Ω *Using this data as a reference IEEE SW Test Workshop 27
Elimination of Stub Affect of Stub Solution for Stub Stub Reflection B nuation, d Reflection Frequency, GHz 0 0 2 4 6-10 -20 Affected -30-40 by Stub -50 With Stub Stubless Material : HE 679G, Line Length : 250mm Board thickness : 6.3mm, Depth of Back Drill : 4.0mm Atte *Using this data as a reference Back Drill (Eliminate Stub) Sequential Structure (Reduce Via Length) IEEE SW Test Workshop 28
Conclusion of Higher Speed Approach MWB has a Low signal loss (-3.6dB@ 3GHz)) and suitable for higher speed Probe Card due to a good impedance control and low signal surface roughness (low skin effect ) By using Low loss material and Back Drilling, MWB can be used for more Higher Speed Probe Card IEEE SW Test Workshop 29
Summary Application of MWB is good solution for Higher density and Higher speed of Probe Card. IEEE SW Test Workshop 30
Thank you!! IEEE SW Test Workshop 31