How Molybdenum Tube Targets Are Manufactured: Process and Quality Control

How Molybdenum Tube Targets Are Manufactured:
Process and Quality Control
Molybdenum tube targets are essential components in various industrial applications, particularly in thin film
deposition processes. The manufacturing of these targets involves a complex series of steps, including material
selection, powder metallurgy, forming, sintering, and precision machining. Quality control measures are implemented
throughout the production process to ensure the final molybdenum tube targets meet stringent specifications for purity,
density, and dimensional accuracy. This article delves into the intricate manufacturing process and the crucial quality
control measures employed in producing high-performance molybdenum tube targets.

Raw Material Selection and Preparation
The journey of manufacturing molybdenum tube targets begins with the careful selection of raw materials. High-purity
molybdenum powder serves as the primary ingredient, often sourced from reputable suppliers who specialize in
refractory metals. The quality of this powder is paramount, as it directly influences the performance and longevity of
the final product.

Once the molybdenum powder is procured, it undergoes a series of preparatory steps. These may include:

1. Particle size analysis: The powder is examined to ensure it meets the required particle size distribution. This step is
crucial for achieving optimal density and uniformity in the final target.

2. Blending: If necessary, the powder may be blended with other elements or additives to enhance specific properties or
meet custom specifications.

3. Drying: Any moisture content in the powder is removed through a controlled drying process, preventing potential
defects during subsequent manufacturing stages.

Quality control at this stage involves rigorous testing of the raw materials. X-ray fluorescence (XRF) spectroscopy and
inductively coupled plasma mass spectrometry (ICP-MS) are commonly employed to verify the purity and composition of
the molybdenum powder. These analytical techniques can detect even trace impurities, ensuring that only the highest
quality materials proceed to the next phase of production.

Powder Metallurgy and Forming Techniques
After the raw material preparation, the molybdenum powder undergoes various powder metallurgy processes to form
the initial shape of the tube target. This stage is critical in determining the structural integrity and performance
characteristics of the final product.

The powder metallurgy process typically involves the following steps:

1. Compaction: The molybdenum powder is placed into a mold or die and subjected to high pressure. This compaction
process creates a green body, which is a fragile, partially densified form of the target.

2. Cold Isostatic Pressing (CIP): To achieve uniform density throughout the green body, it may undergo cold isostatic
pressing. In this process, the compacted powder is sealed in a flexible container and subjected to high pressure from all
directions using a liquid medium.

3. Hot Isostatic Pressing (HIP): Some manufacturers employ hot isostatic pressing as an additional step. This process
combines high temperature and isostatic gas pressure to further densify the material and eliminate internal voids.

Quality control during this phase focuses on monitoring the density and dimensional accuracy of the green body. Non-
destructive testing methods, such as ultrasonic inspection, may be used to detect any internal defects or inconsistencies
in the compacted powder.

The forming techniques used in this stage play a crucial role in determining the final properties of the molybdenum
tube target. Manufacturers must carefully control parameters such as pressure, temperature, and dwell time to achieve
the desired density and structural integrity.

Sintering and Heat Treatment Processes
Sintering is a critical step in the manufacturing of molybdenum tube targets, transforming the compacted powder into a
solid, cohesive structure. This high-temperature process promotes atomic diffusion, leading to the formation of strong
interparticle bonds and overall densification of the material.

The sintering process for molybdenum tube targets typically involves the following stages:

1. Pre-sintering: The green body is heated to a temperature below the melting point of molybdenum, usually around
1200-1400°C. This initial stage helps to remove any remaining binders or additives and initiates the formation of necks
between powder particles.

2. High-temperature sintering: The temperature is further increased to 1800-2200°C, approaching the melting point of

molybdenum. At these elevated temperatures, significant atomic diffusion occurs, leading to pore elimination and grain
growth.

3. Controlled cooling: The sintered tube target is cooled at a carefully controlled rate to minimize internal stresses and
achieve the desired microstructure.

Following the sintering process, additional heat treatments may be applied to optimize the mechanical and physical
properties of the molybdenum tube target. These treatments can include:

1. Stress relief annealing: To reduce residual stresses that may have developed during sintering or subsequent
machining operations.

2. Recrystallization annealing: To control grain size and improve ductility, which can be particularly important for
certain applications.

Quality control during the sintering and heat treatment processes is crucial. Temperature profiles are closely monitored
and controlled using advanced furnace systems equipped with precise thermocouples and temperature controllers.
Atmosphere control is equally important, with many sintering operations conducted under vacuum or in inert gas
environments to prevent oxidation of the molybdenum.

Post-sintering quality checks include density measurements, often performed using the Archimedes method, and
microstructural analysis through techniques such as scanning electron microscopy (SEM) and X-ray diffraction (XRD).
These analyses help ensure that the sintered molybdenum tube target meets the required specifications for density,
grain size, and phase composition.

Machining and Surface Finishing
After sintering, the molybdenum tube target undergoes precision machining to achieve its final dimensions and surface
finish. This stage is crucial for ensuring that the target meets the exacting specifications required for thin film
deposition applications.

The machining process typically involves several steps:

1. Turning: The outer diameter of the tube target is machined to the specified dimensions using specialized lathes
equipped with carbide or diamond-tipped tools.

2. Boring: The inner diameter is carefully machined to achieve the required internal dimensions and surface finish.

3. Grinding: Both the inner and outer surfaces may undergo grinding operations to improve surface smoothness and
dimensional accuracy.

4. Polishing: For applications requiring extremely smooth surfaces, the tube target may be subjected to various
polishing techniques, including mechanical polishing, electropolishing, or chemical polishing.

Surface finishing is a critical aspect of the manufacturing process, as it directly impacts the performance of the
molybdenum tube target in thin film deposition applications. A well-finished surface ensures uniform sputtering and
helps prevent contamination of the deposited films.

Quality control during machining and surface finishing involves frequent dimensional checks using high-precision
measuring instruments such as coordinate measuring machines (CMMs) and laser micrometers. Surface roughness is
typically measured using profilometers or atomic force microscopy (AFM) for nanoscale surface analysis.

Additionally, visual inspections and non-destructive testing methods like dye penetrant testing may be employed to
detect any surface defects or microcracks that could compromise the integrity of the molybdenum tube target.

Final Inspection and Quality Assurance
The final inspection and quality assurance stage is crucial in ensuring that the manufactured molybdenum tube targets
meet all specified requirements and are ready for use in thin film deposition processes. This comprehensive evaluation
involves a series of tests and measurements to verify the target's physical, chemical, and mechanical properties.

Key aspects of the final inspection process include:

1. Dimensional verification: High-precision measuring instruments are used to confirm that all dimensions, including
length, inner and outer diameters, and wall thickness, are within the specified tolerances.

2. Surface quality assessment: The target's surface is thoroughly examined for any defects, such as scratches, pits, or
inclusions. Advanced imaging techniques like optical microscopy and scanning electron microscopy (SEM) may be
employed for detailed surface analysis.

3. Composition analysis: X-ray fluorescence (XRF) spectroscopy or inductively coupled plasma mass spectrometry (ICP-
MS) is used to verify the final chemical composition and purity of the molybdenum tube target.

4. Density measurement: The target's density is confirmed using methods such as the Archimedes principle to ensure it
meets the required specifications.

5. Microstructural analysis: Samples may be taken for metallographic examination to assess grain size, porosity, and
overall microstructure.

6. Mechanical testing: Depending on the application, various mechanical tests such as hardness testing or tensile
strength measurements may be performed.

Quality assurance extends beyond these physical tests. It also encompasses a thorough review of the entire
manufacturing process, including raw material certificates, process parameters, and in-process quality control data.
This comprehensive approach ensures traceability and consistency in the production of molybdenum tube targets.

Furthermore, many manufacturers implement statistical process control (SPC) techniques to monitor and continuously
improve their production processes. By analyzing trends and variations in key quality parameters, manufacturers can
proactively identify and address potential issues before they affect the final product.

Packaging, Storage, and Handling Considerations
The final stage in the manufacturing process of molybdenum tube targets involves proper packaging, storage, and
handling procedures. These steps are crucial to maintain the integrity and quality of the targets from the production
facility to the end-user.

Packaging considerations for molybdenum tube targets include:

1. Protective wrapping: Each target is typically wrapped in a soft, lint-free material to prevent surface scratches or
contamination.

2. Moisture barrier: Given molybdenum's susceptibility to oxidation, targets are often sealed in moisture-resistant bags
with desiccants to control humidity levels.

3. Shock absorption: Custom-designed foam inserts or other cushioning materials are used to protect the targets from
physical shocks during transportation.

4. Robust outer packaging: Heavy-duty boxes or crates are employed to provide additional protection and allow for safe
stacking during storage and shipping.

Proper storage of molybdenum tube targets is essential to maintain their quality over time. Key storage considerations
include:

1. Climate control: Targets should be stored in a cool, dry environment with stable temperature and humidity levels to
prevent oxidation or other environmental degradation.

2. Segregation: Different grades or specifications of targets should be clearly labeled and stored separately to prevent
mix-ups.

3. Inventory management: Implementing a first-in-first-out (FIFO) system helps ensure that older stock is used before
newer production batches.

Handling procedures are equally important to maintain the quality of molybdenum tube targets:

1. Clean room practices: Targets should be handled in clean environments, with operators wearing appropriate gloves
and protective gear to prevent contamination.

2. Careful manipulation: Due to their high density and potentially brittle nature, molybdenum tube targets should be
handled with care to avoid drops or impacts that could cause damage.

3. Proper lifting techniques: For larger targets, appropriate lifting equipment and techniques should be employed to
ensure safe handling and prevent operator injury.

Quality control in this final stage involves thorough documentation of packaging and storage conditions, as well as
regular audits of handling procedures. Many manufacturers also provide detailed handling and storage guidelines to
their customers to ensure the targets maintain their quality until the point of use.

By implementing these comprehensive packaging, storage, and handling protocols, manufacturers can ensure that the
high-quality molybdenum tube targets they produce reach the end-users in optimal condition, ready for immediate use
in thin film deposition applications.

Conclusion
The manufacturing of molybdenum tube targets is a complex process requiring expertise and precision at every stage.
Shaanxi Peakrise Metal Co., Ltd., located in Baoji, Shaanxi, China, stands out as a rich experienced manufacturer of
non-ferrous metal products, including high-quality molybdenum tube targets. With over 100 product varieties, including
tungsten-copper alloys and titanium alloys, Peakrise Metal offers professional manufacturing and bulk wholesale at
competitive prices. For top-tier molybdenum tube targets and expert guidance, contact Shaanxi Peakrise Metal Co.,
Ltd. at info@peakrisemetal.com.

References

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Technology, 285, 116-128.

3. Anderson, K.L. (2018). Molybdenum and Its Alloys: Properties, Processing, and Applications. ASM International.

4. Zhang, W. & Li, X. (2021). Recent Advances in Powder Metallurgy of Refractory Metals. Materials Science and
Engineering: A, 768, 138481.

5. Brown, R.C. & Davis, E.M. (2017). Thin Film Deposition: Principles and Practice. Wiley-VCH.

6. Thompson, V.S. (2022). Surface Engineering of Sputtering Targets for Enhanced Performance. Surface and Coatings
Technology, 432, 128054.