Laser Direct-Write of Materials for Microelectronics Applications

Influence of reinforcement weight fraction on microstructure and properties of submicron WC–Co p/Cu bulk MMCs prepared by direct laser sintering

Effects of dispersion technique and component ratio on densification and microstructure of multi-component Cu-based metal powder in direct laser sintering

The aim of this research is to develop epoxy based adhesive for screen printing on aluminum (Al) and polyimide (PI) substrates in flexible printed circuit (FPC) manufacturing. Two types of aromatic epoxy resins are evaluated in this work including diglycidyl ether of bisphenol-A (DGEBA) and epoxy phenolic novolacs (EPN). The two epoxy resins will also be blended with aliphatic epoxy (PPGDE) for adhesive property enhancement purpose. These epoxy systems can be cured at 170oC for 15 min using metaphenylene diamine (m-PDA) as a curing agent. The compositions of the aromatics epoxies were varied in a range of 50 to 90wt%. From the results, it was found that peel strength of EPN/PPGDE blends was higher than peel strength obtained from DGEBA/PPGDE systems. The maximum peel strength of EPN/PPGDE blends was measured to be 0.561 N/mm at 50/50 mass ratio. These blends were also found to show outstanding adhesive bonding with the aluminum substrate. In addition, it was also found that when the EPN/PPGDE blend at 50/50 mass ratio was modified with 5 phr of CTBN rubber, the resulting adhesive exhibited a good bonding with polyimide substrate providing maximum peel strength of about 0.706 N/mm. The above results also suggest difference in bonding mechanisms of the two adhesive layers and the Al or PI substrates. Consequently, two adhesive layers of epoxy systems with the first layer of EPN/PPGDE blend was applied on Al substrate whereas the CTBN modified EPN/PPGDE blend, a second adhesive layer, which provides a good adhesion on PI film was casted on top of the EPN/PPGDE layer. The obtained peel strength of this two-layered epoxy blends was found to be as high as 0.813 N/mm meeting the industrial requirement. These two-layered epoxy adhesive systems are a good candidate for adhesive bonding of Al and PI substrates through screening printing process.

Balling phenomena in direct laser sintering of stainless steel powder: Metallurgical mechanisms and control methods

PurposeTo identify the effects of laser scan speed and scan spacing on surface morphology, microstructure and structure evolution in direct laser sintering of Cu‐based metal powder.Design/methodology/approachScanning electron microscope, differential thermal analyser (DTA) and X‐ray diffractometer were used to examine the microstructure of the sintered parts.FindingsIt was found that the decrease of the scan speed and scan spacing could lead to densification due to solute‐reprecipitation mechanism. The formation of oxide Cu2O is sensitive to the scan spacing due to the lack of Cu3P protection under the re‐heating condition if using small scan spacing. Furthermore, the result shows that there exist two mechanisms in determining the phosphor distribution. During the laser sintering, concentration diffusion acts as the main mechanism at a fast scan speed and a large scan spacing while solute‐reprecipitation acts as the main mechanism at a low scan speed and small scan spacing.Originality/valueThis paper discloses the influence of process parameters on microstructure evolution and the mechanism of densification in direct laser sintering Cu‐based metal powder. It offers practical help to the researchers who are interested in direct laser sintering metal powder.

Development and characterisation of direct laser sintering multicomponent Cu based metal powder

A direct selective laser sintering (SLS) process was combined with a laser preheating procedure to decrease the temperature gradient and thermal stress, which was demonstrated as a promising approach for additive manufacturing of BaTiO 3 ceramics. The phase compositions in BaTiO 3 ceramics fabricated by SLS were investigated by X‐ray and neutron diffractions. The surface morphologies and cross‐section microstructures were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A dense hexagonal h‐BaTiO 3 layer was formed on the surface and extended to a depth of 500 μm, with a relative density higher than 97% and absence of pores or microcracks. SLS resulted in the formation of the high‐temperature phase, h‐BaTiO 3 , which was retained at room temperature possibly due to the high cooling rate. The grain boundaries of SLSed h‐BaTiO 3 ceramics consist of a Ti‐rich secondary phase. Compared with that of the pressureless sintered t‐BaTiO 3 ceramics, the Vickers hardness of SLSed h‐BaTiO 3 is 70% higher.

This paper focuses on the improvement of ultrasonic defectoscopy used for machine elements produced by direct laser metal sintering. The direct laser metal sintering process introduces the mixed metal powder and performs its subsequent laser consolidation in a single production step. Mechanical elements manufactured by laser sintering often contain many hollow cells due to weight reduction. The popular pulse echo defectoscopy method employing very high frequencies of several GHz is not successful on these samples. The aim of this paper is to present quadraphonic transmission ultrasound defectoscopy which uses low range frequencies of few tens of kHz. Therefore, the advantage of this method is that it enables defectoscopy for honeycombed materials manufactured by direct laser sintering. This paper presents the results of testing performed on AlSi12 sample.

Additive manufacturing (AM) has experienced significant growth in recent years, emerging as a transformative technology with broad applications across various industries. This review explores the advantages, disadvantages, and environmental impacts of AM, an important area of consideration as this technology continues to gain popularity. By analyzing existing literature, we assess the challenges associated with AM processes, particularly in comparison to traditional manufacturing methods. AM has the greatest potential to contribute to sustainable development by the production of lightweight components and complex industrial products with intricate designs. These products are made with minimal material usage. Consequently, also waste and emissions are reduced, which are significant environmental advantages. Overall, this review highlights the importance of AM as a tool for advancing sustainability in manufacturing and offers valuable insights for Continuous Fiber Fabrication, Direct Metal Laser Sintering, and Selective Laser Sintering techniques to enhance their competitive advantage while reducing their environmental impact.

Cranioplasty is the second procedure in the history of neurosurgery after trepanation, and it is still relevant despite the development of civilization and progress in medicine. Each cranioplasty operation is unique because there are no two patients with identical defects of the skull bones. The development of Direct Metal Laser Sintering (DMLS) technique opened up the possibility of direct implant printing of titanium, a biocompatible metal used in medicine. This eliminates the need for producing any intermediate products to create the desired implant. We have produced 8 patient-specific titanium implants using this technique for patients who underwent different decompressive cranioectomies associated with bone tumors. Follow-up duration ranged from 6 to 12 months. We observed no implant-related reactions or complications. In all cases of reconstructive neurosurgery we achieved good clinical and aesthetic results. The analysis of the literature and our own experience in three-dimensional modeling, prototyping, and printing suggests that direct laser sintering of titanium is the optimal method to produce biocompatible surgical implants.

Nanostructured ceramic bulk materials were achieved from nano-Al2O3 ceramic powders via direct selective laser sintering (SLS). SLS as a non-traditional machining technology of Rapid Prototyping was introduced and compared with other ceramic forming technologies. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were applied to analyze the microstructure of the ceramic bulk materials. These results demonstrated that the nano-Al2O3 ceramic powders can be sintered into bulk materials maintained nanostructure with some technological parameters. It was found that the nanostructured ceramic bulk exhibited unique microstructure and was free formed rapidly by this sintering technology.

Direct selective laser sintering (DSLS) of silicon carbide (SiC) ceramics enables the rapid fabrication of complex shaped porous SiC ceramics, making it a promising additive manufacturing technology for SiC materials. However, due to the inability of SiC to maintain a stable liquid phase, challenges arise in solid state sintering via laser, including slow diffusion rates and poor bonding strength in the resulting SiC ceramics. This study investigates the effect of Al2O3‒Y2O3 liquid‐phase sintering additives on the porosity, microstructure, and physical properties of sintered bodies under different energy densities. The results show that by adjusting the energy density during the DSLS process (5.5‒13.9 J mm−2), porous SiC ceramics with porosities ranging from 45.57% to 56.91% can be produced. As the energy density increases from 5.5 to 13.9 J mm−2, the compressive strength, thermal conductivity, resistivity, and specific compressive strength range from 25.00 to 181.80 MPa, 6.12 to 15.66 W m−1 K−1, 4.17 to 34.58 Ω cm, and 17 to 97 MPa cm3 g−1, respectively. This study reveals the microstructural evolution and changes in the physical properties of DSLS‒SiC under the influence of Al2O3‒Y2O3 liquid‐phase sintering additives.

Direct selective laser sintering of iron–graphite powder mixture

Recent studies have shown that direct laser metal sintering (DLMS) produces structures with complex geometry and consequently that allow better osteoconductive properties. The aim of this patient report was to evaluate the early bone response to DLMS implant surface retrieved from human jaws. Four experimental DLMS implants were inserted in the posterior mandible of four patients during conventional dental implant surgery. After 8 weeks, the micro-implants and the surrounding tissue were removed and prepared for scanning electron microscopy (SEM) and histomorphometric analysis to evaluate the bone-implant interface. The SEM and EDX evaluations showed a newly formed tissue composed of calcium and phosphorus. The bone-to-implant contact presented a mean of 60.5 ± 11.6%. Within the limits of this patient report, data suggest that the DLMS surfaces presented a close contact with the human bone after a healing period of 8 weeks.

This paper presents a detailed investigation of the influence of rare earth (RE) oxide (La2O3) addition on densification and microstructure of direct laser sintered submicrometre WC–Cop/Cu metal matrix composites (MMCs) possessing 50.0 wt% reinforcement (WC–Co). It was found that with increasing La2O3 addition to a suitable amount (1.0 wt%), the particulate dispersion was homogenized and the particulate/matrix interfacial bonding was improved. However, with an excessive addition of La2O3 (1.5 wt%), a heterogeneous microstructure consisting of highly accumulated particulates was present. The exact metallurgical roles of RE element in direct laser sintering of particulate reinforced MMCs were addressed. It showed that a proper addition of RE element (i) decreased surface tension of the melt and enhanced solid–liquid wettability; (ii) dragged and/or pinned grain/phase boundaries and resisted grain coarsening and particulate aggregating. However, the balling phenomenon occurred and the activity of RE atoms decreased at an even higher La2O3 content, thereby producing detrimental effects on laser forming ability.