Short answer: silicon nitride guide rings and guide plates outlast alumina by 3–5× in cantilever probe cards, shed no conductive particles, and hold their dimensions over millions of touchdowns. That is why we ship Si₃N₄ probe card guides to probe card manufacturers in Taiwan, Japan, Korea and mainland China.
In a cantilever or vertical probe card, the guide (guide ring, guide plate or ejector insert) positions the needle array over the wafer die and absorbs the Z-axis load of every touchdown. A single wafer-sort step can mean hundreds of thousands of touchdowns per week. The guide must survive:
When the guide wears, the whole probe card — needles, PCB, ceramics — is scrapped early. The guide is a consumable, but a long-life guide multiplies the life of everything around it.
| Property | Si₃N₄ (GPS sintered) | Al₂O₃ 99% | ZrO₂ | Tool steel / POM |
|---|---|---|---|---|
| Hardness (HV) | ~1500–1600 | ~1400–1600 | ~1200–1300 | ≤ 700 / negligible |
| Fracture toughness (MPa·m½) | 6.5–8 | 3–4 | 8–10 | — |
| Wear life as guide | Baseline (longest) | ≈ 1/3–1/5 of Si₃N₄ | Good, but heavy | Short; swells with humidity |
| Chipping / particle risk | Very low | Higher (brittle) | Low | High (metal debris) |
| Electrical insulation | Insulating | Insulating | Insulating | Steel: conductive |
| Water absorption / swelling | 0% | 0% | 0% | POM: yes |
| Density (g/cm³) | 3.20–3.26 | 3.85–3.95 | ≈ 6.0 | ≈ 7.8 / 1.4 |
| Plasma/chemical cleaning | Stable | Stable | Stable | Degrades |
Why Si₃N₄ wins in this specific part: probe guides fail by a mix of sliding wear and edge chipping. Alumina is hard but brittle — corners chip, and those chips are fatal near pads. Zirconia is tough but heavy and its low thermal conductivity can disturb thermal test heads. Silicon nitride combines high hardness with 6.5–8 MPa·m½ toughness: it resists both wear and chipping, and its fine grain structure machines to Ra ≤ 0.1 µm sealing surfaces without any conductive coating.
GPS-sintered Si₃N₄, density ≥ 3.20 g/cm³, hardness ≥ 1500 HV, flexural strength ≥ 750 MPa. RoHS-compliant, no free silica.
OD/ID tolerances to ±0.005 mm; flatness ≤ 0.003 mm on sealing faces; thickness matched sets available.
Ra ≤ 0.1 µm standard on contact faces, ≤ 0.025 µm lapped on request. Edges micro-chamfered to prevent needle-tip damage.
Ultrasonically cleaned and double-bagged, ready for cleanroom intro without re-cleaning.
We currently supply Si₃N₄ probe card guides, ejector inserts and associated ceramics to probe card manufacturers in Taiwan, Japan, Korea and mainland China — from cantilever cards for mature-node testing to vertical/MEMS probes at fine pitch. Repeat-order customers typically qualify us with a first-article dimensional + wear trial, then move to blanket orders with 8–12 week schedules.
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In customer field data on cantilever cards, 3–5× longer guide life is typical, mainly because alumina edges chip while Si₃N₄ resists both wear and chipping. Exact life depends on needle type and cleaning frequency.
Yes. Send a drawing or the worn part itself — we measure, rebuild the drawing, and hold OD/ID to ±0.005 mm with flatness ≤ 0.003 mm.
From prototypes (1–10 pcs) to blanket orders of thousands. Most customers start with first articles and scale after qualification.
Yes — alumina and zirconia guides, ceramic ejector pins and insulating sheets. We recommend the material per your wear data, not the other way around.
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