Gaps in granite bases (platforms) for semiconductors / precision equipment: the core principle is to the crack first, then structurally reinforce, and finally perform precision repositioning and calibration; the use of ordinary marble glue / cement is strictly prohibited. Low-shrinkage, high-idity, anti-static specialized epoxy must be used, and the entire process must be operated in a constant-temperature, dust-free environment.
I. First, determine the type (to decide the solution)
Hairline gap (<0.2mm): surface micro-crack, no misalignment, minimal impact on precision → cleaning penetrating epoxy sealing.Open gap (0.2–2mm): has width, no obvious misalignment → slotting and cleaning rigid epoxy filling grinding and polishing. Structural crack (>2mm through-crack / misalignment): base cracking, flatness / perpendicularity out of tolerance → professional disassembly bonding mechanical reinforcement regrinding and calibration.
Joint gap (at interface of two blocks): joint cracking, light leakage / dust seepage → realignment structural epoxy joint grinding flatness re-measurement.
II. Precision Base Standard Repair Process (iconductor Grade)
- Machine shutdown protection and environmental control
Power off the equipment, remove upper components, and completely unload the base;
Environment: 22±05℃, humidity 40%–60%, dust-free ISO7, to avoid temperature-induced deformation. - Thorough cleaning of the gap (Critical!, debonding will occur)
Dry cleaning: sweep dust with a soft brush → deep blow with 0.4–0.6MPa compressed air, no residual particles
Degreasing: wipe the gap and the 20mm area on both sides with acetone / anhydrous ethanol, wipe dry with a lint-free cloth;
Drying air dry naturally for 30min or blow dry with hot air (≤40℃), water content in the gap <5%. - Gap pretreatment (depending on)
Hairline gap: no slotting required, directly penetrate with epoxy;
0.2–2mm gap: use a diamond thin blade to cut a V-shaped (width 3–5mm, depth 3–5mm), chamfer the slot opening to increase the bonding area;
2mm / through-crack: drill and holes (M6–M8) on both sides, reserve positions for stainless steel connecting plates for later mechanical reinforcement.
- Select the right materials (Semiconductor specialized ordinary glues strictly prohibited)
Tableau
Gap Type Recommended Material Key Indicators
Hairline / Micro-gap Low-viscosity penetrating epoxy Viscosity <10cps, shrinkage <0.5%, anti-static 10⁶–10¹¹Ω Open / Joint gap Rigid structural epoxy (1:1 or2:1) Compressive strength >80MPa, thermal expansion <4.5×10⁻⁶/℃, Shore D hardness >80
Structural crackStructural epoxy stainless steel connecting plates Epoxy strength >3000PSI, connecting plates 304/316L, rust-proof and non-
❌ Prohibited: Marble glue (high shrinkage, brittle), silicone sealant (soft, affects precision), cement (expansion, corrosion).- Filling and curing (Constant temperature dust-free)
Mixing: mix according to the ratio (e.g., 2:1), stir for ≥90s, no bubbles; a small amount of pigment can be added (to match Jinan Green);
Filling:
Micro-gap: slowly inject with a syringe until the gap overflows;
Slotted gap: press and with a putty knife, slightly higher than the surface by 0.5mm (to compensate for shrinkage), avoid bubbles;
Curing: cure at a constant temperature of 2℃ for 24h to reach 80% strength, 48h for full cure; vibration, pressure, and temperature fluctuations are strictly prohibited during this period
- Grinding and Polishing Precision Reset (Core! Restore to nanometer level)
Rough grinding: Diamond grinding discs (#120→#400→#800) grind layer by layer to align with the original plane;
Fine grinding: #1500→#3000 grinding discs, flatness ≤2μm/m, Ra≤0.05μm;
Calibration: Laser interferometer re-checks flatness / perpendicularity, overall fine grinding if necessary;
Anti-static: Spray anti-static coating on the surface, re-measure resistance 10⁶–10¹¹Ω. - Reinforcement and Prevention (Mandatory for structural cracks)
Mechanical reinforcement: Lock stainless steel connecting plates high-strength bolts on both sides of the crack to prevent secondary cracking;
Vibration isolation optimization: Check active / passive vibration isolators, adjust level and pre-compression to reduce vibration stress;
Daily control: Constant temperature 22±0.5℃, avoid rapid heating and cooling, regularly (every 3–6 months) re-check precision.
III. Common Pitfalls (Must Avoid)
Using marble glue / ordinary epoxy: High shrinkage, brittle, prone to secondary cracking, precision not guaranteed;
Incomplete cleaning: Oil / dust leads to debonding and rework;
Room temperature / low temperature curing: Insufficient strength, large deformation, strictly prohibited for semiconductor grade;
Filling without grinding: Surface protrusions / depressions, flatness out of tolerance, equipment motion jamming.
IV. When Factory Return / Professional Treatment is Mandatory
Cracks penetrate the base, obvious misalignment (>0.1mm);
Flatness / perpendicularity exceeds 00 grade (>2μm/m), cannot be repaired on-site;
Base material is loose, weathered, or cracks continue to expand;
Bases of lithography machines / high-end inspection equipment must be repaired by the original factory / precision workshop.
