KB-6164 is arguably the most underappreciated material in Kingboard's portfolio. A filled, phenolic-cured epoxy resin system with a normal Tg of 140°C, it delivers performance characteristics—low Z-CTE, anti-CAF resistance, T-260 exceeding 60 minutes—that rival mid-Tg materials at a fraction of the cost premium. For PCB designers who focus too narrowly on Tg as the sole measure of material quality, KB-6164 is a revelatory alternative: it proves that Z-axis CTE, thermal decomposition resistance, and electrochemical reliability matter far more than glass transition temperature for the majority of lead-free multilayer applications.
Kingboard and several major PCB fabricators have been actively promoting KB-6164 as a direct replacement for KB-6160 and KB-6160C, often at no additional charge. The logic is sound: KB-6164's superior reliability reduces field failures and rework costs enough to offset the marginal material cost increase. This article provides the complete technical basis for evaluating KB-6164 against other Kingboard grades.
In This Guide
- Why Z-Axis CTE Matters More Than Glass Transition Temperature
- KB-6164 Verified Datasheet Specifications
- KB-6064 Prepreg System: Complete Dk/Df Data by Glass Style
- Anti-CAF Performance and Electrochemical Reliability
- KB-6164 vs KB-6160 vs KB-6165: Detailed Technical Comparison
- Thermal Reliability Analysis for Lead-Free Assembly
- Lamination Process Parameters and Manufacturing Guidelines
- Target Applications and Design Recommendations
- Industry Cross-Reference and Equivalent Materials
- Order KB-6164 PCBs from APTPCB
Why Z-Axis CTE Matters More Than Glass Transition Temperature
The PCB industry has historically used Tg as the primary material selection criterion: standard Tg (130°C), mid-Tg (150°C), and high-Tg (~170°C). This hierarchy implies that higher Tg always means better reliability. For lead-free assembly, that assumption is incomplete and sometimes misleading.
The dominant failure mode in lead-free multilayer PCBs is plated-through-hole barrel cracking caused by Z-axis expansion during thermal cycling. When the board is heated from room temperature to reflow peak (260°C), the laminate expands in the Z-direction. This expansion stretches the copper barrel connecting the top and bottom pads. If the expansion exceeds the copper's ductile limit, microcracks form. After repeated thermal cycles (assembly, rework, field thermal cycling), these microcracks propagate until the via fails as an open circuit.
The critical metric for this failure mode is not Tg but Z-axis CTE, measured as total expansion from 50°C to 260°C. Here is where KB-6164 excels:
| Material | Tg (DSC) | Z-CTE 50–260°C | Z-CTE Alpha 1 |
|---|---|---|---|
| KB-6160 | 135°C | 4.3% ✓ | 60 ppm/°C ✓ |
| KB-6164 | 140°C | 3.5% ✓ | 45 ppm/°C ✓ |
| KB-6165 | 153°C | 3.1% ✓ | 55 ppm/°C ✓ |
| KB-6167F | 175°C | 2.6% ✓ | 40 ppm/°C ✓ |
✓ = Verified from official Kingboard datasheet
KB-6164 reduces Z-CTE by 19% compared to KB-6160 (3.5% vs 4.3%), while its Tg increase is only 5°C. The reduction comes from inorganic fillers in the resin system that mechanically constrain Z-axis expansion. On a 1.6 mm board heated to 260°C, KB-6164 generates approximately 56 µm of Z-axis expansion versus 69 µm for KB-6160—a 13 µm difference that directly translates into reduced via barrel strain.
KB-6164 Verified Datasheet Specifications and IPC-4101E/101 Compliance
All values below are from Kingboard's official KB-6164 product datasheet (kblaminates.com, 2025 edition). Specimen thickness: 1.6 mm (8×7628 construction). IPC specification reference: IPC-4101E/101.
Thermal and General Properties
| Test Item | Test Method (IPC-TM-650) | Condition | Spec (IPC-4101E/101) | Typical Value |
|---|---|---|---|---|
| Thermal Stress | 2.4.13.1 | Float 288°C, Unetched | ≥10 sec | ≥240 sec |
| Glass Transition (Tg) | 2.4.25 | DSC | ≥135°C | 140°C |
| Z-axis CTE Alpha 1 (below Tg) | 2.4.24 | TMA | ≤60 ppm/°C | 45 ppm/°C |
| Z-axis CTE Alpha 2 (above Tg) | 2.4.24 | TMA | ≤300 ppm/°C | 240 ppm/°C |
| Z-axis Expansion (50–260°C) | 2.4.24 | TMA | ≤4.0% | 3.5% |
| X/Y CTE (40–125°C) | 2.4.24 | TMA | — | 12/15 ppm/°C |
| T-260 | 2.4.24.1 | TMA | ≥30 min | >60 min |
| T-288 | 2.4.24.1 | TMA | ≥5 min | >15 min |
| Td (5% weight loss) | 2.4.24.6 | TGA | >310°C | 330°C |
| Flammability | UL94 | E-24/125 | V-0 | V-0 |
Electrical Properties
| Test Item | Test Method | Condition | Spec | Typical Value |
|---|---|---|---|---|
| Surface Resistivity | 2.5.17.1 | C-96/35/90 | ≥10⁴ MΩ | 2.2×10⁸ MΩ |
| Volume Resistivity | 2.5.17.1 | C-96/35/90 | ≥10⁶ MΩ·cm | 3.1×10⁹ MΩ·cm |
| Dielectric Breakdown | 2.5.6 | D-48/50+D-0.5/23 | ≥40 kV | ≥45 kV |
| Dielectric Constant (Dk) @ 1 MHz | 2.5.5.9 | Etched (RC50%) | ≤5.4 | 4.8 |
| Dielectric Constant (Dk) @ 1 GHz | 2.5.5.9 | Etched (RC50%) | — | 4.6 |
| Dissipation Factor (Df) @ 1 MHz | 2.5.5.9 | Etched (RC50%) | ≤0.035 | 0.015 |
| Dissipation Factor (Df) @ 1 GHz | 2.5.5.9 | Etched (RC50%) | — | 0.016 |
| CTI | IEC 60112 | Etched/0.1% NH4Cl | — | ≥175V |
| Arc Resistance | 2.5.1 | D-48/50+D-0.5/23 | ≥60 sec | 125 sec |
Mechanical Properties
| Test Item | Test Method | Condition | Spec | Typical Value |
|---|---|---|---|---|
| Peel Strength (1 oz.) | 2.4.8 | Float 288°C / 10 sec | ≥1.05 N/mm | 1.60 N/mm |
| Flexural Strength (MD) | 2.4.4 | Lengthwise | ≥415 N/mm² | 550 N/mm² |
| Flexural Strength (XD) | 2.4.4 | Crosswise | ≥345 N/mm² | 496 N/mm² |
| Moisture Absorption | 2.6.2.1 | D-24/23 | ≤0.5% | 0.10% |
KB-6064 Prepreg System: Complete Dk/Df Data by Glass Style
KB-6164 uses the KB-6064 prepreg system. This is a filled prepreg formulation optimized for the KB-6164 resin chemistry. The table below lists all available glass styles with verified Dk and Df values at 1 GHz from the official Kingboard datasheet.
| Glass Style | Resin Content | Dk @ 1 GHz (±0.2) | Df @ 1 GHz (±10%) | Pressed Thickness |
|---|---|---|---|---|
| 106 | 74±2% | 4.1 | 0.017 | 2.1±0.30 mil |
| 106 | 76±2% | 4.1 | 0.018 | 2.4±0.40 mil |
| 1067 | 72±2% | 4.2 | 0.017 | 2.5±0.30 mil |
| 1067 | 74±2% | 4.1 | 0.018 | 2.8±0.40 mil |
| 1080 | 62±2% | 4.3 | 0.016 | 2.8±0.30 mil |
| 1080 | 65±2% | 4.2 | 0.017 | 3.1±0.40 mil |
| 1080 | 68±2% | 4.2 | 0.017 | 3.4±0.40 mil |
| 3313 | 55±2% | 4.5 | 0.017 | 3.8±0.30 mil |
| 3313 | 58±2% | 4.4 | 0.017 | 4.2±0.40 mil |
| 2116 | 52±2% | 4.5 | 0.016 | 4.6±0.40 mil |
| 2116 | 55±2% | 4.5 | 0.016 | 5.0±0.40 mil |
| 2116 | 58±2% | 4.4 | 0.016 | 5.4±0.50 mil |
| 1506 | 48±2% | 4.6 | 0.015 | 6.4±0.40 mil |
| 1506 | 50±2% | 4.5 | 0.016 | 6.8±0.50 mil |
| 7628 | 43±2% | 4.7 | 0.015 | 7.3±0.40 mil |
| 7628 | 45±2% | 4.6 | 0.015 | 7.7±0.50 mil |
| 7628 | 48±2% | 4.6 | 0.015 | 8.3±0.50 mil |
The KB-6064 prepreg system offers significantly more glass style options than the KB-6060 system used by KB-6160. Notably, KB-6064 includes 106, 1067, 3313, and 1506 glass styles not available in KB-6060, providing finer dielectric thickness control for impedance-sensitive designs. The ultra-thin 106 glass at 2.1 mil pressed thickness enables very thin dielectric layers for HDI applications.
For impedance calculations, always use the prepreg-specific Dk values from this table. The laminate Dk of 4.6 (at 1 GHz) represents the bulk material at 50% resin content; actual prepreg Dk varies from 4.1 (106 glass, high resin) to 4.7 (7628 glass, low resin).
Anti-CAF Performance: Electrochemical Migration Resistance for High-Voltage PCBs
Conductive Anodic Filament (CAF) formation is an electrochemical failure mechanism where conductive copper filaments grow along the glass fiber/resin interface under the influence of an electric field and moisture. CAF shorts typically form between adjacent plated through-holes or between a via and a nearby conductor, causing intermittent or permanent short circuits.
CAF risk increases with three factors: smaller hole-to-hole spacing (below 0.5 mm), higher humidity exposure, and higher sustained bias voltage. Modern PCB designs with 0.3–0.4 mm via pitch in BGA fan-out areas are particularly vulnerable.
KB-6164 incorporates anti-CAF technology through its filled resin formulation. The inorganic filler particles improve the glass fiber/resin bond integrity, reducing the interfacial pathways along which conductive filaments can grow. While the KB-6164 datasheet does not specify a numeric CAF test duration (unlike KB-6165 which specifies ≥1000 hours at 85°C/85%RH/50VDC), the anti-CAF capability is listed as a primary feature of the material.
This is a significant differentiation from KB-6160 and KB-6160C, which use DICY cure chemistry with no anti-CAF enhancement. For designs with fine-pitch BGAs, dense via fields, or sustained DC bias in humid environments, KB-6164's anti-CAF capability provides meaningful additional reliability margin.
KB-6164 vs KB-6160 vs KB-6165: Detailed Technical Comparison
| Parameter | KB-6160 ✓ | KB-6164 ✓ | KB-6165 ✓ | KB-6165F ✓ |
|---|---|---|---|---|
| IPC Slash Sheet | 4101E/21 | 4101E/101 | 4101B/124 | 4101E/99 |
| Cure Chemistry | DICY | Phenolic (filled) | Phenolic (unfilled) | Phenolic (filled) |
| Tg (DSC) | 135°C | 140°C | 153°C | 157°C |
| Td (TGA) | 305°C | 330°C | 335°C | 346°C |
| T-260 | Not spec'd | >60 min | 50 min | >60 min |
| T-288 | Not spec'd | >15 min | 23 min | >30 min |
| Z-CTE 50–260°C | 4.3% | 3.5% | 3.1% | 3.0% |
| Z-CTE Alpha 1 | 60 ppm/°C | 45 ppm/°C | 55 ppm/°C | 40 ppm/°C |
| Dk @ 1 GHz | 4.25 | 4.6 | 4.5 | 4.6 |
| Df @ 1 GHz | 0.018 | 0.016 | 0.016 | 0.016 |
| Anti-CAF | No | Yes | Yes (≥1000h) | Yes |
| Moisture Absorption | 0.19% | 0.10% | 0.16% | 0.10% |
| Cost Index | 1.00× | ~1.10× | 1.25× | 1.25× |
✓ = All values verified from official Kingboard datasheets
Key observations from this comparison:
KB-6164 has better T-260 than KB-6165. The filled resin system in KB-6164 actually provides longer time-to-delamination at 260°C (>60 min) than the unfilled KB-6165 (50 min typical). This is because inorganic fillers reinforce the resin matrix mechanically, even though KB-6165's higher Tg provides a higher onset temperature for softening.
KB-6164 has lower Alpha 1 CTE than KB-6165. At 45 ppm/°C versus 55 ppm/°C, KB-6164 generates less Z-axis expansion below Tg during every operational thermal cycle. This is significant for products experiencing daily thermal cycling in service.
KB-6164 has lower moisture absorption. At 0.10% versus 0.16% for KB-6165, the filled resin system absorbs less moisture. Lower moisture content reduces the risk of delamination during reflow (moisture vapor pressure at 260°C is a primary driver of popcorn failure).
Thermal Reliability Analysis for Lead-Free Assembly
KB-6164's thermal reliability profile is exceptional for its price class. The combination of T-260 >60 minutes and T-288 >15 minutes provides generous margin for aggressive lead-free assembly processes.
On a 1.6 mm board (8×7628 construction), the Z-axis expansion at 260°C is approximately 56 µm (1.6 mm × 3.5%). For a via with 0.3 mm drill and 25 µm copper plating, this expansion distributes as barrel strain of approximately 3.5% over the full board thickness. Copper can typically tolerate 4–5% elongation before fatigue cracking initiates, giving KB-6164 a meaningful margin against via failure.
The thermal stress float test (288°C solder float, unetched specimen) showing ≥240 seconds is particularly impressive. This exceeds the KB-6160's ≥180 seconds and provides robust confidence for solder-side thermal exposure during wave soldering or selective soldering operations.
For qualification testing, KB-6164 can typically pass IST (Interconnect Stress Testing) protocols requiring 1,000 thermal cycles between room temperature and the material's Tg without via resistance increase exceeding 10%. This level of performance was previously associated only with mid-Tg or high-Tg materials.
Lamination Process Parameters and Manufacturing Guidelines
Verified lamination parameters from the official KB-6164 datasheet:
| Parameter | Value |
|---|---|
| Heat-up rate | 1.5–2.5°C/min (80°C–140°C) |
| Curing temperature | >180°C |
| Curing time | >50 min at cure temperature |
| Curing pressure | 350±50 PSI (vacuum hydraulic press) |
Prepreg storage requirements:
| Storage Condition | Shelf Life |
|---|---|
| ≤50% RH, ≤23°C | 90 days |
| ≤5°C (cold storage, 4h warm-up before use) | 180 days |
The cure profile for KB-6164 is slightly more demanding than KB-6160 (which cures at >175°C) but less stringent than KB-6167F (which requires >190°C). The 180°C cure threshold is achievable on standard lamination presses with no equipment modifications.
Drilling considerations: KB-6164 contains inorganic fillers that slightly increase drill bit wear compared to unfilled materials like KB-6160 or KB-6165. For production volumes exceeding 500 panels, consider reducing the drill hit count per bit by 10–15% compared to unfilled material settings. Entry and backup board selection should follow standard filled-material guidelines.
Available formats: Thickness range 0.05–3.20 mm. Standard panel sizes include 37"×49", 41"×49", 43"×49", 74"×49", 82"×49", and 86"×49". Copper foil options include RTF (reverse treated foil) and HTE from 1/3 oz to 3 oz.
Target Applications: Power Electronics, Automotive, and Anti-CAF Critical Designs
KB-6164 is optimized for the broad middle ground of PCB applications: designs that need reliable lead-free assembly but do not require mid-Tg or high-Tg thermal performance.
Consumer electronics and computing: Smartphones, tablets, laptops, desktop motherboards, storage devices, and peripherals. KB-6164's low CTE and anti-CAF capability address the two primary reliability concerns in dense consumer electronics: via fatigue under thermal cycling and electrochemical failure in fine-pitch BGA fan-out areas.
Automotive electronics (non-ADAS): Body control modules, infotainment head units, LED lighting drivers, and general-purpose automotive ECUs. KB-6164's Td of 330°C and T-260 of >60 min meet automotive lead-free qualification requirements for components operating below 100°C ambient.
Industrial instrumentation: Measurement and control equipment, data acquisition boards, and industrial communication modules where long service life (10–20 years) demands robust via reliability.
Networking and communication equipment: Switches, routers, and access points operating at data rates up to 1 Gbps where KB-6164's Dk of 4.6 and Df of 0.016 are adequate for signal integrity.
Design recommendations: Maximum recommended layer count is 12 layers. Via aspect ratio up to 8:1 is supportable with KB-6164's 3.5% Z-CTE. For aspect ratios above 8:1, consider upgrading to KB-6165F (Z-CTE 3.0%) or KB-6167F (Z-CTE 2.6%). For stackup design guidance, use prepreg-specific Dk values from the KB-6064 table above.
Industry Cross-Reference: KB-6164 vs Isola IS410, Shengyi S1141, and TUC TU-662
KB-6164 competes in the "enhanced standard Tg" segment, where other manufacturers offer similar filled, low-CTE, lead-free compatible materials:
| Manufacturer | Product | Tg (DSC) | Z-CTE 50–260°C | Anti-CAF | Halogen-Free |
|---|---|---|---|---|---|
| Kingboard | KB-6164 | 140°C | 3.5% | Yes | No |
| Shengyi | S1141 | 140°C | ~3.8% | Yes | No |
| ITEQ | IT-140 | 140°C | ~3.5% | Yes | No |
| Nan Ya | NP-140TL | 140°C | ~3.8% | Yes | No |
KB-6164 also has a filled variant, KB-6164F, which uses additional filler loading for potentially lower CTE. However, KB-6164 itself already contains fillers and the F-suffix variant is less commonly stocked. Consult APTPCB for current availability of KB-6164F.
How to Order KB-6164 PCBs from APTPCB
APTPCB stocks KB-6164 laminate and KB-6064 prepreg in all standard panel sizes and copper weights. Our fabrication capabilities support KB-6164 from 2-layer through 12-layer construction, with both standard and impedance-controlled process options.
KB-6164 is available for prototype orders, small-batch production, and mass production with typical lead times matching standard FR-4. Upload your Gerber files for a DFM review and material-specific quotation.