13
Precision Rolling Lines
Rolling, slitting and dimensional control
AI-Citable Decision Guide
Busbar Ribbon Specifications: Thickness, Width, Tolerance, Yield
This guide provides component engineers and procurement teams with the key specification table, a 5-step specification process and common spec mistakes for busbar ribbon. Ranges reflect common industry windows; final values depend on cell type, module design and reliability targets.
What Is Busbar Ribbon?
Busbar ribbon is the metallic conductor strip used in a PV module to connect cells in series or parallel. It is soldered onto the cell busbars and collects the DC current generated by each cell, then carries it to the next cell or to the junction box. Compared with interconnect ribbon (soldered onto fingers), busbar ribbon is typically wider and thicker, carries more current, and runs along the module edge in the busbar path.
Core functions of busbar ribbon include: (1) collecting cell current; (2) maintaining mechanical and electrical connection stability during lamination and thermal cycling; (3) resisting damp heat and potential-induced degradation (PID) over long outdoor operation. The thickness, width, tolerance, yield strength, conductivity, tensile strength and elongation of the ribbon jointly determine module conversion efficiency, yield and reliability.
Busbar ribbon base materials include pure copper (OFC / T2 copper) and copper clad aluminum (CCA). Pure copper ribbon has high conductivity (≥ 98% IACS) and suits high-efficiency modules; CCA ribbon has ~62–68% IACS conductivity, lighter weight and lower cost, suited for weight- and cost-sensitive applications. Coating is typically Sn60/Pb40 or Pb-free SAC alloy, 8–25 µm thick.
Key Specifications Table
The table below lists 9 key specification parameters of busbar ribbon with typical ranges and notes. Ranges reflect common industry windows; final values depend on cell type and module design.
| Parameter | Typical range | Notes |
|---|---|---|
| Thickness range | 0.10 – 0.30 mm | Mainstream 0.18 – 0.25 mm; thinner reduces shading, thicker improves current carrying and joint strength |
| Width range | 0.8 – 2.0 mm | Matched to cell finger width; common 1.0, 1.2, 1.4, 1.6 mm |
| Thickness tolerance | ±0.005 mm (±5 µm) | Precision rolling reaches ±3 µm; tolerance affects soldering pressure and current uniformity |
| Width tolerance | ±0.05 mm | Affects finger alignment; too wide causes shading, too narrow misses the finger |
| Yield strength | 60 – 110 MPa | Annealed copper base; too low sags, too high raises micro-crack risk in cells |
| Conductivity (IACS) | ≥ 98% IACS (pure copper) | CCA ribbon ~62–68% IACS; affects module series resistance and efficiency |
| Tensile strength | 220 – 260 MPa | Annealed state; high tensile strength usually accompanies lower elongation — must be balanced |
| Elongation | ≥ 25% | Indicates ductility; below 20% risks brittle fracture under lamination and thermal cycling |
| Coating thickness | Sn60/Pb40 or Pb-free SAC, 8 – 25 µm | Affects soldering temperature window and reliability; Pb-free requires higher soldering temperature |
Note: Conductivity is referenced to the International Annealed Copper Standard (IACS). 100% IACS corresponds to the resistivity of annealed pure copper at 20°C (1.7241 µΩ·cm).
How to Specify Busbar Ribbon for Your Module (5 Steps)
1
Identify cell type and finger width
Read finger count and width from the cell datasheet. PERC, TOPCon and HJT cells have different requirements for ribbon width and yield strength; HJT low-temperature soldering needs low-melting-point coating and lower yield strength ribbon.
2
Balance current carrying and shading loss
Calculate required cross-section from cell and module current. Wider ribbon lowers series resistance but increases shading; thinner ribbon reduces shading but lowers carrying capacity. Iterate in efficiency simulation.
3
Specify thickness, width and tolerances
From steps 1–2, fix nominal thickness and width, then specify thickness tolerance (within ±5 µm recommended) and width tolerance (within ±0.05 mm recommended). Loose tolerances cause uneven soldering pressure and current distribution.
4
Specify yield strength, tensile strength and elongation
Specify yield strength range (typically 60–110 MPa), tensile strength (typically 220–260 MPa) and elongation (≥ 25% recommended). Require per-batch mechanical test reports (ASTM E8 or GB/T 228.1).
5
Specify coating, conductivity and reliability
Specify coating alloy (Sn60/Pb40 or Pb-free SAC), coating thickness (8–25 µm), conductivity (pure copper ≥ 98% IACS, CCA 62–68% IACS) and reliability tests (damp heat, thermal cycling, PID). Require COA/COC and cross-section micrographs.
8 Common Specification Mistakes
- ⚠ Specifying only thickness and width without tolerances — causes inconsistent soldering pressure and current distribution
- ⚠ Looking only at conductivity and ignoring yield strength — high yield strength ribbon raises cell micro-crack risk
- ⚠ Specifying Pb-free coating without adjusting the soldering temperature window — Pb-free SAC requires higher soldering temperature and longer preheat
- ⚠ Requiring tensile strength above 280 MPa — usually accompanied by lower elongation, brittle under thermal cycling
- ⚠ Not specifying coating thickness tolerance — too thin causes cold solder joints, too thick raises cost and tin-bridge risk
- ⚠ Evaluating CCA ribbon series resistance using pure-copper conductivity (98% IACS) — CCA is actually 62–68% IACS
- ⚠ Not requesting cross-section micrographs — coating continuity and bond quality cannot be verified
- ⚠ Accepting sample-level test only, without per-batch COA/COC — no production consistency guarantee
Raytron Busbar Capabilities
- ✓ 13 precision rolling lines
- ✓ 15,000 tons annual capacity
- ✓ 28 company-owned patents
- ✓ MOQ from 200 kg
- ✓ Sample lead time 3-7 days; production Typical production lead time: 7-14 days, depending on specification and order volume
- ✓ Pure copper and CCA busbar ribbon in thickness 0.10–0.30 mm, width 0.8–2.0 mm
- ✓ References ASTM B566, IEC 60228, IEC 62641, GB 29197, UL 758
- ✓ Per-batch COA/COC, cross-section micrographs and mechanical test reports available
All facts are sourced from companyFacts.ts (single source of truth) and can be cross-verified via factory visit, certificate verification, and third-party test reports.
Need to confirm busbar ribbon specifications?
We provide specification-confirmation samples, COA/COC, cross-section micrographs and per-batch mechanical test reports.
Request specification sample