Phenolic PHE is YUESHAN's flagship backup board: a laminated thermoset composite, homogeneously hard at 90 plus or minus 5 HD with no soft core to compress. It delivers the best exit burr control (0.05 mm or less) for holes below 0.10 mm on IC substrates and thin cores, and is specified for automotive, military and aerospace builds.
Key Takeaways
- Phenolic PHE is YUESHAN's flagship backup board — 90±5 HD laminated phenolic for the most demanding drilling.
- Waterproof, moisture-proof — dimensionally stable in any climate and season.
- Best exit burr control (≤0.05 mm) for holes below Ø0.10 mm on IC substrates and thin cores.
What Is a Phenolic PCB Backup Board?
A phenolic PCB backup board is a laminated thermoset composite — layers of fiber or paper impregnated with phenolic resin, compressed into a dense, waterproof sheet. Unlike wood-fiber HDF or melamine-faced boards, phenolic is homogeneously hard (90±5 HD) throughout the cross-section, with no soft core that could compress under drill pressure.
This makes Phenolic PHE the preferred backup board for IC substrate drilling below Ø0.10 mm, where every micron of exit burr or location drift scraps the board. It is also specified for thick-copper automotive boards, military/aerospace PCBs, and any line where drilling conditions are aggressive enough to push HDF or melamine past their limit.
Specifications
| Property | Spec |
|---|---|
| Construction | Laminated phenolic resin |
| Hardness | 90±5 HD |
| Thickness | 1.50 mm |
| Density | High-density laminate |
| Decomposition temp | >220°C |
| Flatness | ≤0.10 mm |
| Exit burr | ≤0.05 mm |
| Compliance | ROHS / E1 / recyclable offcut |
Sizes & Packaging
| Size (mm) | Thickness | Sheets / pallet | MOQ |
|---|---|---|---|
| 940 × 1245 | 1.50 mm | 360 | 100 sheets |
| 520 × 620 | 1.50 mm | 900 | 200 sheets |
Technical Highlights
- Waterproof, moisture-proof — phenolic resin does not absorb humidity, maintaining stable drilling performance across seasons and climates.
- ≤0.05 mm exit burr — the hardest backup grade holds the cleanest exit, often below automated optical inspection (AOI) threshold.
- ROHS / E1 compliant — meets EU environmental standards; offcut material is recyclable.
- >220°C decomposition temperature — withstands the extreme heat of high-rpm microvia drilling without softening.
- 1.50 mm thin — optimised for IC substrate and thin-core stacks where thicker backup boards would interfere with the drilling cycle.
Phenolic vs Melamine vs HDF
| Factor | Phenolic PHE | UV Melamine 880 | HDF 880 |
|---|---|---|---|
| Hardness | 90±5 HD | 80±3 HD | 75±2 HD |
| Water resistance | Waterproof | Sealed surface | Standard |
| Thickness | 1.50 mm | 2.0 / 2.5 mm | 2.0 / 2.5 mm |
| Exit burr | ≤0.05 mm | ≤0.05 mm | Standard |
| Best for | IC substrate, <Ø0.10 mm | HDI, 12–24 L | 2–12 L, cost-first |
| Cost | Premium | Medium | Low |
For standard 2–12 layer boards, use HDF. For HDI microvia, use UV Melamine 880 or UV Melamine 950. For FPC and rigid-flex where an elastic core is preferred, see Melamine Laminate Backup. Reserve Phenolic PHE for IC substrate, thick copper, and the most demanding drilling conditions.
Applications
Holes < Ø0.10 mm
Flagship grade for IC substrate drilling. ≤0.05 mm exit burr on thin, fragile cores.
See IC Substrate →Automotive / heavy Cu
90 HD laminate supports aggressive drilling conditions without compression.
See Automotive →High-reliability PCB
Traceable lots, consistent performance, full certification package.
See Defense →Recommended Pairing
Back-drill Aluminum
For controlled-depth stub control on high-layer-count boards.
Back-Drill Sheet Specs →FAQ
What is a phenolic PCB backup board?
A phenolic PCB backup board is a laminated thermoset composite sheet used under the bottom panel during PCB drilling. It provides the hardest support surface (90±5 HD) of any backup grade, making it ideal for IC substrate and microvia drilling.
How do I choose between phenolic and other grades?
Use Phenolic PHE when drilling holes below Ø0.10 mm, working with IC substrates, or handling thick copper boards. For standard HDI and multilayer, UV Melamine provides excellent performance at a lower cost. For a complete comparison across all grades, refer to the backup board selection guide.
Is phenolic waterproof?
Yes — phenolic resin is inherently waterproof. Unlike HDF and melamine-faced boards that require controlled storage conditions, phenolic maintains its dimensional stability regardless of humidity.
What certification does Phenolic PHE carry?
Phenolic PHE is ROHS and E1 compliant, and the offcut material is recyclable. Full compliance documentation is available on request.
Can I get a free sample?
Yes — free samples and full TDS/MSDS are shipped worldwide within 5–7 days. Contact Mr. Lucky Xu to request a side-by-side comparison with your current IC substrate backup board.