Through-glass via, commonly abbreviated as TGV, is an important interconnection technology used in advanced packaging, radio-frequency devices, MEMS, sensors, optical systems and wafer-level integration.
TGV glass wafers contain vertical holes or conductive vias extending through the glass substrate. These structures can provide electrical connection, signal routing, thermal paths or alignment features while maintaining the electrical insulation, dimensional stability and optical properties of glass.
However, purchasing TGV glass wafers requires more than specifying the wafer diameter and via size. The glass composition, wafer thickness, hole geometry, pitch, sidewall quality, metallization process and inspection standard all affect manufacturability, reliability and cost.
This guide explains how to select a TGV glass wafer supplier and what technical information should be included in an RFQ.
What Is a TGV Glass Wafer?
A TGV glass wafer is a glass substrate containing holes that pass completely through the wafer thickness.
Depending on the application, the vias may remain unfilled or may be coated, lined or completely filled with conductive metal.
A typical TGV manufacturing process may include:
- Glass wafer preparation
- Via pattern definition
- Through-hole formation
- Cleaning and sidewall treatment
- Seed-layer deposition
- Metal plating or via filling
- Surface grinding or polishing
- Redistribution-layer processing
- Inspection and electrical testing
TGV structures may be used for:
- Vertical electrical interconnection
- Wafer-level packaging
- Fan-out packaging
- RF modules
- MEMS packaging
- Image sensors
- Optical sensors
- Interposers
- Microfluidic devices
- Hermetic package structures
- Antenna-in-package applications
The final TGV specification must be designed around the electrical, mechanical, thermal and packaging requirements of the device.
Why Glass Is Used for Through-Via Substrates
Glass provides a combination of properties that can be useful in semiconductor and packaging applications.
Potential advantages include:
- Electrical insulation
- Low electrical loss
- Adjustable coefficient of thermal expansion
- Good dimensional stability
- Smooth wafer surfaces
- Optical transparency
- Compatibility with fine-feature processing
- Availability in wafer formats
- Suitability for RF and high-frequency applications
- Potential for hermetic packaging structures
The exact performance depends on the glass composition and manufacturing process.
Not every glass wafer is suitable for TGV processing. The material must tolerate via formation, cleaning, metallization, thermal cycling and downstream packaging without excessive cracking, warpage or delamination.
1. Select the Correct Glass Type
Glass composition is one of the first decisions in a TGV project.
Common categories include:
- Borosilicate glass
- Aluminosilicate glass
- Fused silica
- Quartz glass
- Alkali-free glass
- Photosensitive glass
- Specialty packaging glass
Each material has different electrical, thermal, optical and mechanical characteristics.
Borosilicate glass
Borosilicate glass is widely used for packaging, MEMS and sensor applications.
Its potential advantages include:
- Good thermal stability
- Relatively low thermal expansion
- Compatibility with wafer-level processing
- Good chemical resistance
- Availability in multiple wafer sizes
- Suitability for anodic bonding in selected structures
It may be considered for:
- MEMS packaging
- Pressure sensors
- Microfluidic devices
- Wafer-level caps
- Interposer structures
- General TGV development
Aluminosilicate glass
Aluminosilicate glass can provide relatively high mechanical strength and thermal resistance.
It may be selected for:
- High-density packaging
- Thin glass substrates
- Applications requiring improved mechanical durability
- Thermal-cycle-sensitive structures
- Fine-pitch TGV designs
The exact composition should be reviewed because different aluminosilicate glasses can have significantly different electrical and thermal properties.
Fused silica
Fused silica offers high purity, excellent optical transmission and a very low coefficient of thermal expansion.
It may be suitable for:
- Optical packaging
- Photonics
- High-temperature applications
- Precision sensor structures
- Low-expansion assemblies
- High-frequency applications
However, via formation and metallization on fused silica may require specialized processing because of its material hardness and surface chemistry.
Alkali-free glass
Alkali-free glass is designed to reduce mobile-ion contamination.
It may be considered for:
- Semiconductor packaging
- Display-related processing
- Applications sensitive to sodium or potassium migration
- High-reliability electronic structures
When alkali content is important, the RFQ should specify the required chemical composition or maximum permitted alkali concentration.
Photosensitive glass
Photosensitive glass can be patterned and selectively modified through exposure and thermal treatment.
It may support:
- Complex microstructures
- High-density holes
- Cavities and channels
- Integrated microfluidic features
- Precise three-dimensional structures
The supplier should confirm whether the requested via profile, thickness and sidewall quality are compatible with the selected photosensitive process.
Glass Selection Parameters
The buyer should compare the following material properties:
| Material parameter | Why it matters |
|---|---|
| Coefficient of thermal expansion | Influences stress during bonding and thermal cycling |
| Glass transition temperature | Affects high-temperature processing capability |
| Dielectric constant | Influences signal propagation and impedance |
| Dielectric loss | Important for RF and high-frequency devices |
| Electrical resistivity | Affects insulation performance |
| Thermal conductivity | Influences heat dissipation |
| Young’s modulus | Affects stiffness and mechanical stress |
| Poisson’s ratio | Used in mechanical modeling |
| Surface roughness | Affects bonding and metallization |
| Chemical durability | Important during cleaning and plating |
| Optical transmission | Required for optical and sensor applications |
| Alkali content | Important for contamination-sensitive devices |
The glass type should be selected together with the packaging material, metal system and expected operating temperature.
2. Define the Wafer Diameter and Thickness
Common TGV wafer diameters may include:
- 100 mm
- 150 mm
- 200 mm
- 300 mm
- Custom round substrates
- Rectangular glass panels
Wafer diameter affects:
- Equipment compatibility
- Mask design
- Handling method
- Via count
- Production cost
- Inspection method
- Packaging and transportation
Wafer thickness may range from thin interposer substrates to relatively thick glass packaging structures.
The correct thickness depends on:
- Required mechanical strength
- Via aspect ratio
- Package height
- Electrical design
- Handling method
- Bonding structure
- Grinding and polishing requirements
Thin glass can reduce the required via depth and electrical path length, but it is more difficult to handle.
Thick glass can provide greater rigidity but may increase:
- Via formation time
- Via taper
- Metallization difficulty
- Filling time
- Residual stress
- Total processing cost
The buyer should specify both the starting thickness and final thickness after grinding or polishing.
3. Specify the Via Diameter Correctly
Via diameter is one of the most important TGV parameters.
A supplier may request:
- Top-side via diameter
- Bottom-side via diameter
- Minimum internal diameter
- Nominal via diameter
- Via diameter tolerance
These values may be different when the hole has a tapered profile.
For example, a via described only as 50 μm may be interpreted in several ways:
- 50 μm at the top surface
- 50 μm at the bottom surface
- 50 μm average diameter
- 50 μm minimum opening
- 50 μm after metallization
- 50 μm before metallization
The RFQ must define where the diameter is measured and whether the dimension applies before or after metal deposition.
Typical Via Size Categories
TGV dimensions can vary widely according to the application.
| Via category | General application |
| Large vias | Mechanical alignment, fluidic access or low-density interconnection |
| Medium vias | Standard packaging and sensor interconnection |
| Small vias | High-density electrical routing |
| Microvias | Fine-pitch interposers and advanced packaging |
As the via diameter decreases, the process becomes more sensitive to:
- Wafer thickness
- Aspect ratio
- Sidewall taper
- Debris removal
- Seed-layer continuity
- Plating uniformity
- Void formation
- Inspection capability
Smaller vias do not automatically provide a better design. Via dimensions should be selected according to electrical requirements and manufacturing capability.
4. Evaluate Via Aspect Ratio
The via aspect ratio is commonly defined as:
Aspect ratio = wafer thickness ÷ via diameter
For example, a 500 μm-thick wafer with a 100 μm via has an aspect ratio of 5:1.
A higher aspect ratio may allow smaller vias in thicker wafers, but it also increases process difficulty.
High-aspect-ratio vias can create challenges involving:
- Hole formation
- Sidewall uniformity
- Debris removal
- Cleaning
- Seed-layer coverage
- Metal plating
- Void control
- Inspection
- Electrical continuity
Before finalizing the design, buyers should confirm the supplier’s demonstrated capability for the specific combination of:
- Glass type
- Wafer thickness
- Via diameter
- Via pitch
- Via profile
- Metallization method
A supplier’s minimum via diameter may only apply to thin glass or a limited via density. It should not be treated as a universal capability.
5. Define the Via Profile
TGV holes may have different cross-sectional profiles.
Common profiles include:
- Straight cylindrical vias
- Tapered vias
- Double-sided tapered vias
- Hourglass-shaped vias
- Conical vias
- Stepped vias
- Rounded-entry vias
Straight via
A straight via has relatively consistent diameter through the wafer thickness.
Potential benefits include:
- Predictable geometry
- Efficient use of substrate area
- Easier electrical modeling
- Suitable for dense layouts
However, straight high-aspect-ratio holes may be more difficult to metallize uniformly.
Tapered via
A tapered via has different diameters at the top and bottom surfaces.
Potential benefits include:
- Improved access for seed-layer deposition
- Easier plating
- Reduced risk of incomplete sidewall coverage
- Improved cleaning
The disadvantages may include:
- Larger surface opening
- Reduced routing density
- Different electrical geometry
- More complex dimensional inspection
Hourglass via
An hourglass profile may be created by processing the wafer from both sides.
This can reduce the maximum drilling depth from either surface and may support thicker wafers.
The central meeting point must be controlled to avoid:
- Misalignment
- Restricted internal diameter
- Debris trapping
- Irregular metal filling
- Electrical discontinuity
The drawing should show the complete via cross-section, not only the top opening.
6. Determine the Via Pitch and Pattern
Via pitch is the center-to-center distance between adjacent vias.
The minimum practical pitch depends on:
- Via diameter
- Glass thickness
- Via formation method
- Heat-affected or modified region
- Required glass web thickness
- Crack risk
- Metallization design
- Redistribution-layer spacing
- Inspection capability
The buyer should provide:
- X-direction pitch
- Y-direction pitch
- Staggered or aligned pattern
- Edge-to-via distance
- Via-to-via spacing
- Exclusion zones
- Alignment marks
- Total via count per wafer
High via density can affect:
- Wafer mechanical strength
- Warpage
- Metal-plating uniformity
- Thermal stress
- Processing time
- Yield
- Unit price
A small test array should be produced before moving to a full-wafer, high-density design.
7. Choose the Via Formation Method
Several processes can be used to create through-glass vias.
The appropriate method depends on:
- Glass composition
- Wafer thickness
- Via diameter
- Via density
- Sidewall-quality requirement
- Taper requirement
- Production volume
- Cost target
Possible methods include:
- Laser-based processing
- Laser modification followed by chemical etching
- Mechanical drilling
- Ultrasonic machining
- Abrasive processing
- Plasma-assisted processing
- Photolithographic processing of photosensitive glass
- Combined processes
Laser-based via formation
Laser processing can provide flexible patterning without physical masks.
Potential advantages include:
- Programmable via locations
- Fast design changes
- Compatibility with multiple hole shapes
- Suitable for prototype and production work
Potential concerns include:
- Heat-affected zones
- Microcracks
- Recast material
- Sidewall roughness
- Taper
- Debris
- Residual stress
The final result depends on the glass type, laser parameters and post-processing.
Laser modification and etching
In this process, selected regions of the glass are modified before chemical removal.
Potential advantages may include:
- Fine features
- Reduced mechanical damage
- High-density patterns
- Controlled via profiles
Important considerations include:
- Material compatibility
- Etch selectivity
- Sidewall roughness
- Process uniformity
- Cleaning requirements
Mechanical or abrasive processing
Mechanical methods may be suitable for larger holes or lower-density designs.
They may offer:
- Straightforward processing
- Good control for larger features
- Suitability for thick substrates
However, mechanical stress and edge chipping must be controlled.
The buyer should focus on the finished-hole specification rather than requiring a particular manufacturing method unless the process itself is critical to product qualification.
8. Define Sidewall Quality Requirements
Via sidewall quality affects metallization, reliability and electrical continuity.
Important inspection items include:
- Sidewall roughness
- Microcracks
- Chipping
- Debris
- Recast material
- Heat-affected region
- Surface contamination
- Internal constriction
- Irregular taper
- Glass damage around the via opening
A rough sidewall may improve mechanical adhesion in some structures but can also create:
- Discontinuous seed layers
- Current-density concentration
- Plating voids
- Increased conductor resistance
- Reliability risks
The RFQ should define the acceptable inspection method and defect limit.
Possible methods include:
- Optical microscopy
- Cross-sectional microscopy
- Confocal measurement
- Scanning electron microscopy
- X-ray inspection
- Surface profilometry
- Three-dimensional optical measurement
9. Select the Metallization Structure
TGV metallization may involve coating the via sidewall, partially filling the via or completely filling the via with conductive material.
Common structures include:
- Sidewall metal lining
- Conformal metal coating
- Partial metal fill
- Complete copper fill
- Conductive paste fill
- Metal-filled via with redistribution layers
- Metal caps on both wafer surfaces
The correct structure depends on:
- Required electrical resistance
- Current-carrying capability
- Signal frequency
- Thermal requirements
- Mechanical reliability
- Package thickness
- Surface-planarity requirement
- Downstream bonding process
10. Understand the Metallization Process
A typical metallization process may include:
- Via cleaning
- Surface activation
- Adhesion-layer deposition
- Seed-layer deposition
- Electroplating or electroless plating
- Via filling or sidewall coating
- Surface metal removal
- Grinding or polishing
- Annealing
- Redistribution-layer formation
- Electrical testing
The process must produce continuous metal coverage through the complete via.
Potential metallization defects include:
- Seed-layer discontinuity
- Plating voids
- Seams
- Copper overburden
- Surface pits
- Via blockage
- Poor adhesion
- Metal delamination
- Cracks caused by thermal stress
- Non-uniform resistance
11. Choose the Metal System
Copper is commonly considered for conductive TGV structures because of its electrical and thermal conductivity.
Other metals or layers may also be used depending on the design.
Possible materials include:
- Copper
- Titanium
- Chromium
- Nickel
- Gold
- Silver
- Tungsten
- Conductive paste
- Multi-layer metal stacks
A typical metal stack may include:
- Adhesion layer
- Barrier layer
- Seed layer
- Plated conductor
- Surface-finish layer
The buyer should specify:
- Required conductor material
- Adhesion-layer material
- Barrier-layer requirement
- Final surface finish
- Minimum metal thickness
- Maximum resistance
- Bonding compatibility
- Corrosion-resistance requirement
The supplier should also understand the downstream process, such as:
- Wire bonding
- Flip-chip bonding
- Soldering
- Thermocompression bonding
- Conductive adhesive bonding
- Redistribution-layer formation
12. Sidewall Coating vs Full Via Filling
Sidewall-coated TGV
In a sidewall-coated structure, metal covers the internal wall of the via while the center remains open.
Potential advantages include:
- Lower metal volume
- Shorter plating time
- Reduced metal stress
- Lower processing cost
- Possible use as an open channel
Potential limitations include:
- Higher electrical resistance than a fully filled via
- Greater sensitivity to coating discontinuity
- More difficult electrical inspection
- Limited current-carrying capability
Fully filled TGV
A fully filled via contains conductive material across most or all of its cross-section.
Potential advantages include:
- Lower electrical resistance
- Higher current capacity
- Better thermal conduction
- Potentially improved surface integration
Potential challenges include:
- Longer plating time
- Void formation
- Internal seams
- Greater thermal-mechanical stress
- Surface overburden
- More complex grinding and polishing
The buyer should define whether the requirement is:
- Conformal coating
- Minimum wall thickness
- Partial fill percentage
- Void-free fill
- Complete metal fill
- Planarized metal surface
13. Control Copper-to-Glass Thermal Stress
Glass and copper expand at different rates during temperature changes.
This mismatch can create stress around the via and may lead to:
- Glass cracking
- Copper protrusion
- Metal delamination
- Interface separation
- Wafer warpage
- Reliability failure during thermal cycling
Stress depends on:
- Glass coefficient of thermal expansion
- Via diameter
- Via pitch
- Wafer thickness
- Copper volume
- Annealing conditions
- Operating-temperature range
- Redistribution-layer design
The supplier should evaluate the complete material stack rather than considering the glass and metal independently.
For high-reliability applications, thermal cycling and cross-sectional analysis may be required.
14. Specify Surface Metallization and Redistribution Layers
Some projects require metal only inside the vias. Others require patterned metal lines on one or both wafer surfaces.
Possible surface structures include:
- Metal pads
- Redistribution layers
- Ground planes
- Antenna structures
- Bonding rings
- Solderable pads
- Wire-bond pads
- Electroplated bumps
The RFQ should specify:
- Top-side metal pattern
- Bottom-side metal pattern
- Metal thickness
- Line width
- Line spacing
- Pad dimensions
- Surface finish
- Alignment tolerance between vias and pads
- Passivation requirement
- Bonding method
A drawing should identify whether the supplier is responsible for:
- TGV hole formation only
- Hole formation and seed layer
- Hole formation and metal filling
- Complete TGV plus redistribution layers
- Final wafer-level interposer fabrication
15. Define Wafer Flatness, Bow and Warp
TGV processing and metal deposition can change wafer geometry.
Important dimensional parameters include:
- Total thickness variation
- Bow
- Warp
- Local flatness
- Edge exclusion
- Surface roughness
- Parallelism
Flatness becomes especially important for:
- Lithography
- Wafer bonding
- Temporary bonding
- Redistribution-layer processing
- Grinding
- Inspection
- Automated wafer handling
High via density and thick copper structures can increase wafer stress.
The buyer should specify whether bow and warp limits apply:
- Before via processing
- After via formation
- After metallization
- After thermal treatment
- At final delivery
16. Establish Inspection Requirements
A complete TGV inspection plan may include several levels.
Incoming glass inspection
- Wafer diameter
- Thickness
- Total thickness variation
- Bow and warp
- Surface roughness
- Edge condition
- Scratch and defect inspection
- Material certification
Via inspection
- Via diameter
- Top and bottom opening
- Taper angle
- Via pitch
- Position accuracy
- Sidewall quality
- Chipping
- Crack inspection
- Blocked-via inspection
Metallization inspection
- Metal thickness
- Seed-layer continuity
- Void inspection
- Fill percentage
- Surface overburden
- Adhesion
- Electrical resistance
- Isolation resistance
Final wafer inspection
- Wafer thickness
- Flatness
- Bow and warp
- Surface roughness
- Pad dimensions
- Redistribution-layer alignment
- Visual defects
- Wafer map
- Packaging condition
The inspection standard should be agreed upon before production begins.
17. Electrical Testing Requirements
Depending on the application, electrical testing may include:
- Continuity testing
- Via resistance
- Insulation resistance
- Leakage current
- Open-circuit detection
- Short-circuit detection
- Daisy-chain testing
- High-frequency characterization
- Current-carrying test
The buyer should specify:
- Maximum resistance per via
- Maximum resistance variation
- Minimum insulation resistance
- Test voltage
- Test current
- Sampling level
- Wafer-map format
- Pass/fail criteria
Electrical testing becomes more important after complete metallization or redistribution-layer processing.
18. Reliability Testing
High-reliability TGV structures may require:
- Thermal cycling
- High-temperature storage
- Temperature-humidity testing
- Pressure-cooker testing
- Metal-adhesion testing
- Bond-strength testing
- Mechanical bending
- Wafer-level warpage measurement
- Cross-sectional inspection
- Current-stress testing
The required reliability plan depends on the final application.
An RF device, optical sensor and automotive package may require different qualification conditions.
The supplier should understand:
- Operating-temperature range
- Storage-temperature range
- Package assembly process
- Expected service life
- Environmental exposure
- Required qualification standard
19. Prototype Development Before Volume Production
TGV projects should normally begin with a design review and prototype stage.
A practical development sequence may include:
- Material selection
- Via-layout review
- Process-feasibility evaluation
- Test-coupon production
- Small-array fabrication
- Metallization trial
- Cross-sectional inspection
- Electrical testing
- Thermal or reliability testing
- Full-wafer pilot production
Starting directly with a dense full-wafer pattern can increase development cost and make process problems more difficult to isolate.
A test coupon can be used to evaluate:
- Several via diameters
- Different via pitches
- Multiple taper angles
- Different metal thicknesses
- Sidewall coating versus full fill
- Resistance variation
- Thermal stress
20. How to Evaluate a TGV Glass Wafer Supplier
A qualified supplier should be able to discuss the complete process, not only the minimum hole diameter.
Evaluate the following areas:
Material capability
- Available glass types
- Wafer diameters
- Thickness range
- Material certificates
- Traceability
- Custom glass sourcing
Via capability
- Minimum and maximum via diameter
- Supported aspect ratio
- Pitch capability
- Taper control
- Position tolerance
- Sidewall-quality control
- Crack and chipping inspection
Metallization capability
- Seed-layer deposition
- Adhesion and barrier layers
- Sidewall plating
- Partial or full filling
- Copper-planarization capability
- Surface metallization
- Redistribution layers
- Electrical testing
Quality capability
- Dimensional metrology
- Cross-sectional inspection
- X-ray inspection
- Surface analysis
- Electrical testing
- Wafer mapping
- Process traceability
- Inspection reports
Production capability
- Prototype service
- Pilot production
- Volume production
- Yield management
- Capacity planning
- Lead-time control
- Packaging and shipping
Engineering support
- Design-for-manufacturing review
- Drawing review
- Material recommendation
- Via-structure recommendation
- Metallization support
- Reliability analysis
- Failure analysis
TGV Glass Wafer RFQ Checklist
An accurate RFQ should include the following information.
Glass substrate
- Glass type
- Material grade
- Wafer diameter
- Starting thickness
- Final thickness
- Total thickness variation
- Bow and warp
- Surface roughness
- Edge profile
- Optical-transmission requirement
- Coefficient-of-thermal-expansion requirement
Via dimensions
- Via diameter
- Top opening diameter
- Bottom opening diameter
- Minimum internal diameter
- Via depth
- Via aspect ratio
- Via taper angle
- Via pitch
- Via position tolerance
- Edge-to-via distance
- Total via count
- Via pattern drawing
Via quality
- Maximum chipping
- Maximum crack length
- Sidewall roughness
- Debris requirement
- Heat-affected-zone limit
- Blocked-via acceptance
- Inspection method
- Sampling standard
Metallization
- Metal material
- Adhesion layer
- Barrier layer
- Seed layer
- Sidewall coating or full fill
- Required metal thickness
- Maximum void size
- Maximum via resistance
- Surface finish
- Top-side pad pattern
- Bottom-side pad pattern
- Redistribution-layer requirement
Testing and quality documents
- Dimensional report
- Material certificate
- Wafer map
- Cross-sectional images
- Electrical test report
- Plating-thickness report
- Bow and warp report
- Reliability-test requirement
- Traceability requirement
- Packaging specification
Commercial information
- Prototype quantity
- Pilot quantity
- Annual forecast
- Required delivery date
- Target unit price
- Incoterms
- Shipping destination
- Special packaging requirements
Common RFQ Mistakes
Buyers should avoid submitting incomplete requirements such as:
- “Need 200 mm TGV wafer”
- “Via size is 50 μm”
- “Need copper metallization”
- “Please quote according to drawing” when no cross-section is provided
These requests do not define:
- Glass composition
- Wafer thickness
- Top and bottom via diameter
- Via pitch
- Taper
- Metal thickness
- Sidewall coating or full filling
- Electrical resistance
- Quality acceptance criteria
An incomplete RFQ usually produces a preliminary estimate rather than an accurate production quotation.
Frequently Asked Questions
What glass is best for TGV wafers?
There is no universal best glass. The correct material depends on thermal expansion, dielectric properties, optical performance, processing temperature, mechanical strength and bonding requirements.
What is the minimum TGV via diameter?
The minimum achievable diameter depends on the glass type, wafer thickness, aspect ratio, via pitch and formation method. Buyers should request demonstrated capability for their complete wafer design.
Can TGV holes be completely filled with copper?
Yes, some TGV structures use complete copper filling. However, the design must address plating voids, thermal stress, copper protrusion, wafer warpage and surface planarization.
Is a tapered TGV better than a straight TGV?
Neither profile is universally better. Tapered vias can simplify seed deposition and plating, while straight vias can support higher routing density. The correct choice depends on the process and electrical design.
What information is required for a TGV quotation?
The supplier needs the glass type, wafer size, thickness, via diameter, via pitch, via count, via profile, position tolerance, metallization structure, testing requirement and order quantity.
Can a TGV supplier provide only drilled glass without metal?
Yes. Projects may purchase unmetalized TGV glass, seed-coated wafers, partially plated wafers or fully metallized interposers. The required process scope should be clearly stated.
How is TGV via quality inspected?
Common methods include optical inspection, three-dimensional measurement, cross-sectional analysis, scanning electron microscopy, X-ray inspection and electrical testing.
What causes voids in metal-filled TGVs?
Possible causes include incomplete seed coverage, restricted via geometry, poor cleaning, non-uniform current distribution, gas trapping and unsuitable plating conditions.
Why is a prototype run important?
A prototype run verifies via geometry, metallization continuity, resistance, wafer stress and reliability before the buyer commits to full-wafer or high-volume production.
Conclusion
Selecting a TGV glass wafer supplier requires a complete review of the glass substrate, via geometry, metallization structure and quality-control process.
The most important purchasing parameters include:
- Glass composition
- Wafer diameter and thickness
- Via diameter and aspect ratio
- Via pitch and pattern
- Sidewall quality
- Taper and position tolerance
- Metallization method
- Metal thickness and fill quality
- Electrical resistance
- Wafer bow and warp
- Inspection and reliability requirements
A technically complete RFQ should include both a top-view layout and a via cross-section drawing.
Send the supplier the glass material, wafer diameter, thickness, via dimensions, via pitch, metallization requirements, quantity and inspection standard for a manufacturability review and quotation.