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Halogen-free FR-4 Guide: Shengyi S1155 vs Kingboard KB-6165G
QUICK ANSWER Halogen-free FR-4 is a flame-retardant, glass-reinforced epoxy laminate in which chlorine and bromine stay below industry limits: 900 ppm each and 1,500 ppm combined. It is selected when a PCB program needs lower-halogen material declarations without leaving mainstream rigid-board processing. The laminate grade, Tg, Z-axis expansion, and assembly profile still determine reliability.
A request that says only "FR-4" leaves resin chemistry, thermal margin, impedance behavior, and compliance evidence open. Halogen-free FR-4 must be an engineering requirement, not an option added after the PCB is quoted.
What Is Halogen-free FR-4
Halogen-free FR-4 uses glass cloth and flame-retardant epoxy while limiting bromine and chlorine. "Halogen-free" does not mean zero halogen, lead-free, RoHS compliant, or harmless under fire; these are separate declarations.
Name the material grade and the applicable customer or IEC 61249-2-21 limits, then request a material declaration or certificate of conformity. This connects the specification to the Halogen-free FR-4 delivered on the production lot.
Halogen-free FR-4 Material Comparison
Shengyi S1155 and Kingboard KB-6165G are practical Halogen-free FR-4 choices with different thermal classifications. These are typical datasheet values, not design guarantees; confirm the revision, construction, and test method before release.
| Property | Shengyi S1155 | Kingboard KB-6165G | Practical Decision |
|---|---|---|---|
| Tg by DSC | 140°C | 155°C | KB-6165G offers more thermal margin. |
| Td at 5% loss | 380°C | 365°C | Td alone does not predict plated-through-hole life. |
| Z expansion 50–260°C | 3.5% | 2.8% | Lower expansion generally reduces stress on plated holes. |
| Water absorption | 0.10% | 0.11% | Storage and bake control still matter. |
| Best fit | General electronics with moderate assembly demand | Multilayer or repeated lead-free thermal exposure | Choose against the actual stack-up and reflow count. |
Compare Dk or Df only when frequency, resin content, test method, and copper condition match. For controlled impedance, use the production stack-up and effective Dk.
Halogenated FR-4 vs Halogen-free FR-4
The main difference is the flame-retardant system, but the choice also affects cost, documentation, processing, and fire risk. Halogen-free FR-4 does not automatically outperform every halogenated laminate.
| Factor | Halogenated FR-4 | Halogen-free FR-4 |
|---|---|---|
| Cost and supply | Usually the lowest-cost, broadest-stock option. | Often carries a premium that depends on grade, thickness, copper, and quantity. |
| Health and safety | A fire or improper disposal can generate more corrosive, irritating halogen-containing gases. | Reduces Cl/Br-related emissions, but combustion products remain hazardous and require normal controls. |
| Performance | Wide range from standard Tg to high-performance grades. | Also available in multiple Tg and loss classes; the label alone proves no thermal or electrical advantage. |
| Manufacturing | Established drilling and lamination windows. | Drilling, desmear, and lamination must follow the qualified material system. |
| Applications | Cost-sensitive consumer and industrial boards without a low-halogen mandate. | OEM environmental programs, telecom, computing, instruments, and export products with material restrictions. |
Advantages of Halogen-free FR-4 in PCB Applications
Halogen-free FR-4 adds the most value when design, sourcing, and compliance records address it from the start. Three benefits matter:
Clearer environmental qualification. A named grade and lot evidence support customer substance surveys and auditable records.
Lower corrosive-halogen exposure in a fire. Reduced bromine and chlorine can limit related acid-gas and residue concerns, but a burning PCB remains hazardous.
Useful thermal options. Grades such as Kingboard KB-6165G combine Halogen-free FR-4 chemistry with mid-Tg and lower Z-axis expansion, which may suit multilayer boards better than an ordinary-Tg option.
Factors to Consider When Choosing FR-4 Material
The right laminate is the lowest-cost qualified material that meets the finished PCB requirements. Check four items before approving Halogen-free FR-4:
Cost. Compare the complete quote. Stock status, thickness, copper, panel utilization, minimum order, and a no-substitution instruction can change the result.
Environment. State the required Br, Cl, and combined limits, plus the evidence needed at shipment. Do not treat RoHS, lead-free assembly, and Halogen-free FR-4 as interchangeable claims.
Product performance. Match Tg, Td, T260/T288, Z-axis expansion, CTI, CAF resistance, moisture, and Dk/Df to the layer count, vias, operating conditions, frequency, and solder cycles.
Manufacturing. Put the material code, approved alternates, or "no substitution" on the drawing. Confirm stack-up and impedance; for high-reliability builds, validate coupons, microsections, and thermal cycling.
Conclusion
Choose Shengyi S1155 when ordinary-Tg Halogen-free FR-4 meets the assembly and reliability target; consider Kingboard KB-6165G when higher Tg and lower Z-axis expansion add useful margin. PCBgogo supplies both halogenated and halogen-free FR-4 options: send your Gerber files, stack-up, material code, compliance limits, and substitution rule for a manufacturability review and a production-ready PCB quote.
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Frequently Asked Questions
Is Halogen-free FR-4 the same as RoHS compliant?
No. RoHS restricts specific hazardous substances, while Halogen-free FR-4 controls chlorine and bromine content under a separate material definition. Request both declarations when the product specification requires both.
Can Shengyi S1155 replace Kingboard KB-6165G directly?
Not automatically. Their typical Tg and Z-axis expansion differ, so substitution can change lamination behavior, assembly margin, impedance construction, and reliability evidence. Approve an alternate only after stack-up and process review.
Does Halogen-free FR-4 always improve PCB reliability?
No. Reliability depends on the complete laminate system, copper and glass construction, via geometry, moisture control, and thermal history. A qualified halogenated high-Tg grade can outperform an unsuitable low-Tg Halogen-free FR-4 in a demanding build.
What should I provide when requesting a Halogen-free FR-4 quote?
Provide Gerber and drill files, layer stack-up, finished thickness, copper weights, material grade, halogen limits, required documentation, impedance requirements, surface finish, solder profile, and approved substitution policy. These details let the fabricator price the actual build instead of guessing.
