Precision sealing alloy materials suitable for glass sealing, ceramic sealing, electronic packaging, vacuum devices, hermetic connectors, and thermal expansion matching structural parts.
Kovar alloy 4J29 is an iron-nickel-cobalt based fixed-expansion alloy, also known as Kovar alloy. It has thermal expansion properties similar to hard glass, borosilicate glass, and some ceramic materials, and is commonly used in glass-to-metal sealing, ceramic-metal sealing, electronic packaging, vacuum devices, and highly airtight structural components. Its core value is not high strength or wear resistance, but thermal expansion matching, sealing reliability, and airtight stability.
By focusing on application scenarios, boundaries of advantages, and non-recommended scenarios, it helps sales, customer service, and quoting staff quickly determine whether the material meets current part requirements.
It has a stable coefficient of thermal expansion, good compatibility with hard glass and ceramics, suitable for hermetic sealing, good sealing reliability, suitable for electronic packaging and vacuum devices, good low-temperature structural stability, and can perform post-processing such as CNC machining, stamping, welding, brazing, nickel plating, and gold plating.
Glass-metal sealing parts, ceramic-metal sealing parts, electronic packaging housings, transistor packaging components, sensor packaging components, vacuum tube parts, relay sealing components, microwave device housings, connector housings, lead frames, sealing sockets, optoelectronic device packaging, avionics packaging parts, and highly airtight structural components.
Ordinary low-cost structural parts, high-strength load-bearing parts, high-hardness wear-resistant parts, high thermal conductivity heat dissipation parts, high conductivity copper busbars, lightweight structural parts, large-size low-budget parts, highly corrosive environment parts, elastic snap parts, ordinary decorative parts, and conventional metal parts that do not require thermal expansion matching.
The following parameters come from product information and material knowledge fields, used for design review, quotation communication, and preliminary judgment before material selection.
| Material positioning | Precision sealing alloy materials suitable for glass sealing, ceramic sealing, electronic packaging, vacuum devices, hermetic connectors, and thermal expansion matching structural parts. |
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| Precision performance | Keva Alloy 4J29 is suitable for CNC turning, milling, drilling, tapping, stamping, drawing, welding, and brazing. Precision fittings typically require high dimensional accuracy, flatness, coaxiality, and surface quality. Actual accuracy is affected by material condition, part dimensions, wall thickness, machining path, welding heat effects, coating thickness, and sealing thermal cycles. Key sealing surfaces, positioning surfaces, and airtight mating surfaces should have separate tolerances and roughness controls. |
| Dimensional tolerances | For CNC machining of Koval alloy 4J29, the standard dimensional tolerances can be referenced ± 0.02mm-±0.10mm, while ordinary structural parts can be evaluated at ±0.05mm-±0.20mm. The overall dimensional tolerances after stamping, stretching, welding, and sealing can be even greater. This value is a standard reference range and does not guarantee absolute tolerances for all structures. The sealing surface, positioning holes, assembly surfaces, lead holes, and sealing fit positions should be individually marked with tolerances according to airtightness requirements. |
| Minimum Wall Thickness | The wall thickness of ordinary CNC machined structures is recommended to be no less than 0.8mm-1.0mm. Stamped housings, sealing rings, thin-walled tube shells, and lead structures can be designed thinner according to process capabilities, but deformation, welding, sealing, and airtightness risks need to be assessed. The area used for sealing and thermal cycling should not be too thin to avoid deformation, cracking, or stress concentration during sealing. |
| Recommended wall thickness | Standard sealing rings, housings, end caps, and structural components are recommended to be 1.0mm-2.5mm; areas requiring welding, brazing, glass sealing, ceramic sealing, or bearing assembly forces are recommended to be appropriately thickened. The wall thickness of thin-walled encapsulated shells should be determined based on tensile processes, welding methods, sealing stress, and airtightness requirements to avoid deformation or leakage caused by being too thin. |
| Minimum aperture | CNC drilling can achieve smaller hole diameters, but deep holes, lead holes, and sealing holes require focused control of burrs, roundness, and hole wall quality. For general designs, the recommended aperture is no less than 0.8mm-1.0mm. Holes for glass or lead sealing should be individually designed according to glass beads, ceramic parts, metal leads, and sealing gaps, ensuring cleanliness, no burrs, and dimensional stability. |
| Assembly clearance | For ordinary metal assembly, it is recommended to reserve 0.02mm-0.10mm on one side; for ordinary plug-in and assembly, it is recommended to reserve 0.10mm-0.30mm per side. The gaps between glass sealing, ceramic sealing, and brazed structures cannot be simply treated as ordinary mechanical assembly; they should be individually designed according to the sealing material, coefficient of thermal expansion, solder or glass flowability, sealing temperature, and airtightness requirements. If subsequent treatments such as nickel plating or gold plating are performed, the effect of coating thickness on the gap should be considered. |
| Detailed performance | 4J29 is suitable for machining holes, grooves, steps, chamfers, welded edges, sealing rings, tube shells, flanges, lead holes, and small precision structures. Fine text and decorative textures are not the core applications of this material; marking is usually recommended through laser marking, etching, or assembly marking. The sealing area should avoid sharp corners, burrs, contamination, and overly deep narrow grooves to prevent stress concentration and sealing defects. |
| Surface effect | The original machined surface of 4J29 usually has a silver-gray or gray metallic texture. After grinding and polishing, a relatively smooth metal surface is obtained, and sandblasting produces a uniform matte finish. When used for electronic packaging and airtight components, surfaces usually focus more on cleanliness, coating quality, weldability, and sealing reliability rather than decorative appearance. Common appearance treatments include nickel plating, gold plating, silver plating, and spot polishing. |
Based on material characteristics and suitable product ranges, customer needs are broken down into easier application directions to determine.
Glass-metal sealing parts, ceramic-metal sealing parts, electronic packaging housings, transistor packaging components, sensor packaging components, vacuum tube parts, relay sealing components, microwave device housings, connector housings, lead frames, sealing sockets, optoelectronic device packaging, avionics packaging parts, and highly airtight structural components.
Precision sealing alloy materials suitable for glass sealing, ceramic sealing, electronic packaging, vacuum devices, hermetic connectors, and thermal expansion matching structural parts.
The main feature of Koval Alloy 4J29 is its controllable thermal expansion performance, allowing it to form good expansion matching with hard glass, borosilicate glass, or certain ceramic materials within a certain temperature range, thereby reducing thermal stress generated during sealing and cooling. It is commonly used in highly airtight and highly reliable electronic, vacuum, optoelectric, and sensor packaging fields. Compared to ordinary steel, stainless steel, and aluminum alloys, the advantage of 4J29 is not strength or cost, but sealing stability and thermal expansion matching ability.
Based on wall thickness, hole position, assembly clearance, dimensional tolerances, and material usage risks, determine in advance whether the part structure is suitable for Kovar Alloy/4J29.
Post-processing of Kovar Alloy/4J29 affects appearance, dimensions, hole position, assembly clearance, and usage validation results, and should be explained in advance during quotation, DFM review, and sample confirmation stages.
Post-processing should focus on appearance display, dimensional fitting, connection assembly, and testing verification. Parts involving assembly positions need to be reserved in advance for machining, coating, and trial assembly allowances.
For common issues such as threads, snaps, strength, temperature resistance, and weather resistance, identify in advance whether the material needs to be replaced or if another processing method should be used.
When customer demand exceeds Kovar Alloy/4J29 material boundaries, it is necessary to combine strength, temperature resistance, toughness, long-term stability, and mass production goals to promptly recommend alternative materials or processing technologies.
If lower expansion coefficients and dimensional stability are required, Invar alloy 4J36 can be chosen; If other glass or ceramic sealing and matching are needed, fixed-expansion alloys such as 4J33 or 4J42 can be selected according to the sealing material; If you only need a regular metal casing, you can choose 304 stainless steel, 316 stainless steel,6061 Aluminum Alloy, or carbon steel; If high thermal conductivity packaging is required, copper-tungsten, molybdenum-copper, oxygen-free copper, or aluminum-silicon materials can be considered; If high corrosion-resistant packaging is required, evaluation should be combined with coatings or stainless steel materials.
If the customer's core requirements are glass sealing, ceramic sealing, hermetic sealing, vacuum devices, or thermal expansion matching, Kova Alloy 4J29 is the appropriate choice. If the customer only has ordinary structural brackets, housings, or mechanical parts, the cost and processing requirements of 4J29 are relatively high, so it is generally not recommended to prioritize them. When selecting 4J29, focus on confirming the type of sealing material, operating temperature, airtightness level, coating requirements, heat treatment status, and subsequent sealing process.
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