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XRX-10206
DGXRX
The core process of FR-4 multilayer board
1. Process flow of lamination and interconnection
Key technical points of the process, precision requirements
Inner layer production FR-4 core board cutting → LDI laser imaging → acid etching → AOI detection 7 line width tolerance ± 0.05mm
Stacked laminated core board+semi cured sheet (PP sheet) alternately stacked → vacuum hot pressing (180 ℃/400psi) 710 interlayer offset ≤ 75 μ m
Laser drilling CO ₂/UV laser drilling blind buried hole (aperture 0.1-0.2mm) → plasma slag removal 7 hole position accuracy ± 0.03mm
Chemical deposition of copper through hole metallization (0.3 μ m) → electroplating thickening (hole copper ≥ 25 μ m) → hole filling electroplating (HDI board) 710 aspect ratio ≥ 8:1
Surface treatment ENIG immersion gold (contact area)/OSP (welding area)/spray tin (low-cost solution) 36 solder bridge width ≥ 0.1mm
Process innovation:
Mixed pressure design: High frequency range (such as PTFE)+FR-4 digital range, taking into account signal integrity (for 5G base station applications);
Resin plug hole: filling through-hole to prevent welding short circuit (mandatory requirement for automotive electronics);
High Tg material: FR-4 with Tg ≥ 170 ℃ is resistant to lead-free soldering (peak temperature 250 ℃).
2、 FR-4 material characteristics and selection
1. Material composition and performance
Infrastructure: Electronic grade fiberglass cloth+flame-retardant epoxy resin, compliant with UL94 V-0 standard;
Key parameters:
Dielectric constant (Dk): 4.2- 4.7@1GHz (Medium low frequency stable, high frequency needs to be modified);
Glass transition temperature (Tg): 130 ℃ (standard) → 180 ℃ (high heat resistance type);
Mechanical strength: Bending strength>400MPa, twice better than paper substrate.
2. Comparison of FR-4 types
Types, Applicable Scenarios, Advantages, Limitations
The standard FR-4 consumer electronics/industrial control motherboard has low cost (20-50 yuan/㎡) and high high-frequency loss (>3GHz) after mature processing
High Tg FR-4 automotive electronics/lead-free soldering, heat-resistant up to 180 ℃, with a 30% increase in thermal cycling cost
Modified FR-4 high-speed digital circuit (≤ 5GHz) with improved Dk stability (± 0.1) and fewer thickness options
3、 Application Fields and Typical Cases
1. Communication and computing (accounting for 45%)
5G base station: mixed voltage FR-4+high-frequency material (such as RO4350B), 12 layer board supporting 28GHz RF;
Server motherboard: 8-12 layer HDI design, 2oz thick copper power supply, impedance control ± 5%.
2. Automotive electronics (accounting for 25%)
ECU control unit: High Tg FR-4 (Tg ≥ 170 ℃), passed ISO-16750 vibration test;
LED headlight driver: aluminum based embedded heat dissipation+FR-4 circuit layer, resistant to 85 ℃ engine compartment environment.
3. Consumer electronics (accounting for 20%)
Smart home control board: 6-layer FR-4, OSP surface treatment, cost<$5/piece;
COB packaged LED screen: 6-layer board with gold plating treatment, resistant to "caterpillar" effect (such as P1.56 small pitch screen).
4. Industry and Medical
PLC controller: 4-layer FR-4 double-sided grounding, anti EMI interference;
Medical imaging equipment: Low loss modified FR-4 (Df<0.02), ensuring signal accuracy.
4、 Limitations and coping strategies
Effect of defect solution
High frequency loss>5GHz switch to PTFE mixed pressure 7 insertion loss reduced from>2dB to< 0.5dB@10GHz
Adding ceramic filler with high coefficient of thermal expansion (CTE reduced to 10ppm/℃) reduces the risk of BGA welding cracking
Lead free soldering challenges high Tg FR-4+step reflow soldering with a virtual soldering rate of less than 0.5%
The core process of FR-4 multilayer board
1. Process flow of lamination and interconnection
Key technical points of the process, precision requirements
Inner layer production FR-4 core board cutting → LDI laser imaging → acid etching → AOI detection 7 line width tolerance ± 0.05mm
Stacked laminated core board+semi cured sheet (PP sheet) alternately stacked → vacuum hot pressing (180 ℃/400psi) 710 interlayer offset ≤ 75 μ m
Laser drilling CO ₂/UV laser drilling blind buried hole (aperture 0.1-0.2mm) → plasma slag removal 7 hole position accuracy ± 0.03mm
Chemical deposition of copper through hole metallization (0.3 μ m) → electroplating thickening (hole copper ≥ 25 μ m) → hole filling electroplating (HDI board) 710 aspect ratio ≥ 8:1
Surface treatment ENIG immersion gold (contact area)/OSP (welding area)/spray tin (low-cost solution) 36 solder bridge width ≥ 0.1mm
Process innovation:
Mixed pressure design: High frequency range (such as PTFE)+FR-4 digital range, taking into account signal integrity (for 5G base station applications);
Resin plug hole: filling through-hole to prevent welding short circuit (mandatory requirement for automotive electronics);
High Tg material: FR-4 with Tg ≥ 170 ℃ is resistant to lead-free soldering (peak temperature 250 ℃).
2、 FR-4 material characteristics and selection
1. Material composition and performance
Infrastructure: Electronic grade fiberglass cloth+flame-retardant epoxy resin, compliant with UL94 V-0 standard;
Key parameters:
Dielectric constant (Dk): 4.2- 4.7@1GHz (Medium low frequency stable, high frequency needs to be modified);
Glass transition temperature (Tg): 130 ℃ (standard) → 180 ℃ (high heat resistance type);
Mechanical strength: Bending strength>400MPa, twice better than paper substrate.
2. Comparison of FR-4 types
Types, Applicable Scenarios, Advantages, Limitations
The standard FR-4 consumer electronics/industrial control motherboard has low cost (20-50 yuan/㎡) and high high-frequency loss (>3GHz) after mature processing
High Tg FR-4 automotive electronics/lead-free soldering, heat-resistant up to 180 ℃, with a 30% increase in thermal cycling cost
Modified FR-4 high-speed digital circuit (≤ 5GHz) with improved Dk stability (± 0.1) and fewer thickness options
3、 Application Fields and Typical Cases
1. Communication and computing (accounting for 45%)
5G base station: mixed voltage FR-4+high-frequency material (such as RO4350B), 12 layer board supporting 28GHz RF;
Server motherboard: 8-12 layer HDI design, 2oz thick copper power supply, impedance control ± 5%.
2. Automotive electronics (accounting for 25%)
ECU control unit: High Tg FR-4 (Tg ≥ 170 ℃), passed ISO-16750 vibration test;
LED headlight driver: aluminum based embedded heat dissipation+FR-4 circuit layer, resistant to 85 ℃ engine compartment environment.
3. Consumer electronics (accounting for 20%)
Smart home control board: 6-layer FR-4, OSP surface treatment, cost<$5/piece;
COB packaged LED screen: 6-layer board with gold plating treatment, resistant to "caterpillar" effect (such as P1.56 small pitch screen).
4. Industry and Medical
PLC controller: 4-layer FR-4 double-sided grounding, anti EMI interference;
Medical imaging equipment: Low loss modified FR-4 (Df<0.02), ensuring signal accuracy.
4、 Limitations and coping strategies
Effect of defect solution
High frequency loss>5GHz switch to PTFE mixed pressure 7 insertion loss reduced from>2dB to< 0.5dB@10GHz
Adding ceramic filler with high coefficient of thermal expansion (CTE reduced to 10ppm/℃) reduces the risk of BGA welding cracking
Lead free soldering challenges high Tg FR-4+step reflow soldering with a virtual soldering rate of less than 0.5%