Inductor Material Research Articles

Novel FePBNbCr glassy alloys “ SENNTIX” with good soft-magnetic properties for high efficiency commercial inductor cores

According to a recent study, Fe-based glassy alloys are expected good soft-magnetic properties such as high saturation magnetization and lower coercive force. We focused on Fe-based glassy alloys and have succeeded in developing novel glassy Fe 97− x− y P x B y Nb 2Cr 1 ( x = 5–13, y = 7–15) alloys for an inductor material. The glassy alloy series of Fe 97− x− y P x B y Nb 2Cr 1 ( x = 5–13, y = 7–15) have high glass-forming ability with the large critical thickness of 110–150 μm and high B s of 1.25–1.35 T. The glassy alloy powder with chemical composition Fe 77P 10.5B 9.5Nb 2Cr 1 exhibits an excellent spherical particle shape related to the lower melting point and liquid phase point. In addition, Fe–P–B–Nb–Cr powder/resin composite core has much lower core loss of 653–881 kW/m 3, which is approximately 1/3 lower than the conventional amorphous Fe–Si–B–Cr powder/resin composite core and 1/4 lower than the conventional crystalline Fe–Si–Cr powder/resin composite core due to the lower coercive force of 2.5–3.1 A/m. Based on above results, the glassy Fe 77P 10.5B 9.5Nb 2Cr 1 alloy powder enable to achieve ultra-high efficient and high quality products in a commercial inductor. In fact, the surface mounted inductor using Fe–P–B–Nb–Cr powder/resin exhibits the high efficiency of approximately 2.0% compared with the conventional inductors made of the crystalline Fe–Si–Cr powder/resin composite core.

Synthesis, sintering behavior and magnetic properties of Cu-substituted Co2Z hexagonal ferrites

Cu-substituted Z-type Ba3Co2−x Cu x Fe24O41 hexagonal ferrites (0 ≤ x ≤ 1) were prepared by the standard oxide route. Almost single phase Z-type ferrite powders were observed after calcination at 1,260 °C. The permeability of samples sintered at 1,260 °C varies with the Cu content; a maximum permeability at 10 MHz of μ′ = 17 was found for x = 0.6. It is shown that the permeability behavior is determined by the concentration of Z-type ferrite in the sample and the microstructure. Addition of 3 wt% Bi2O3 leads to almost complete densification of Co2Z samples under low temperature ceramic cofiring (LTCC) conditions at 900 °C. However, the permeability of samples sintered at 900 °C is reduced to μ′ = 5 with resonance frequency at 2 GHz. It is shown that Cu-substituted Co2Z ferrites are not stable at T < 1,260 °C. Partial decomposition into other hexagonal ferrites causes a reduction of the permeability. In spite of this severe drawback, Co2Z hexagonal ferrites with Cu modifications are suitable materials for multilayer inductors for high frequency applications.

FePBNbCr soft-magnetic glassy alloys with low loss characteristics for inductor cores

Fe-based glassy alloys with both high saturation magnetization and low magnetic anisotropy have attracted interest in recent study on Mr. Inoue, 2004, and we have succeeded in developing novel glassy Fe 97− x− y P x B y Nb 2Cr 1 ( x = 5–13, y = 7–15) alloys for an inductor material. The glassy alloy series of Fe 97− x− y P x B y Nb 2Cr 1 ( x = 5–13, y = 7–15) have high glass-forming ability with the large critical thickness of 110–150 μm and low coercivity of 2.5–3.1 A/m caused by the structural homogeneity. The Fe 77P 7B 13Nb 2Cr 1 glassy alloy exhibits the largest critical thickness of 150 μm related to the wide super cooled liquid region and the high saturation magnetic flux density ( B s ) of 1.3 T, both of which are higher than those of the conventional amorphous Fe 75Si 10B 12Cr 3 alloy. Hence, Fe–P–B–Nb–Cr powder/resin composite core has much lower core loss of 650 kW/m 3 which is approximately 1/3 lower than the conventional amorphous Fe–Si–B–Cr powder/resin composite core that are annealed at 623 K. In addition, the optimum annealing temperature of 623 K for these glassy alloys was lower than that (723 K) for the ordinary Fe–Si–B–Cr amorphous alloy, which is a significant advantage for the efficiency in mass production of inductor core using soft-magnetic glassy alloy powder.

Co&lt;sub&gt;2&lt;/sub&gt;Z, Co&lt;sub&gt;2&lt;/sub&gt;Y and CoM-Type Hexagonal Ferrites for Multilayer Inductors

Abstract. Hexagonal Co-containing Z-; Y- and M-type ferrites are used as soft magnetic materials for multilayer inductors for operating frequencies up to 3 GHz. Co2Z-type Ba3Co2Fe24O41, iron excess Ba3Co2-yFe24+yO41 (0  y  0.8) and Ba3Co2-CuxFe24O41 (0  x  1.0) ferrites have their stability intervals between 1260-1350°C. The permeability of a ferrite with y = 0.6 sintered at 1300°C is µ = 30 throughout the MHz. Addition of Bi2O3 shifts the maximum shrinkage down to 950°C. Their permeability is µ = 5 because of partial decomposition of the Co2Z phase. Y-type ferrite Ba2Co1.2-xZnxCu0.8Fe12O22 (x = 1.2) sintered at 1100°C shows a permeability of µ = 20. Sintering at 900°C reduces the permeability to µ = 10. M-type BaCo1.2Ti1.2Fe9.6O19 ferrites sintered at 970°C display a permeability of µ = 35.

Novel ${\hbox {Fe}}_{(97-{\rm x-y})}{\hbox {P}}_{\rm x}{\hbox {B}}_{\rm y}{\hbox {Nb}}_{2}{\hbox {Cr}}_{1}$ Glassy Alloys With High Magnetization and Low Loss Characteristics for Inductor Core Materials

Fe-based glassy alloys with both high saturation magnetization and low magnetic anisotropy have attracted interest recently , and we have succeeded in developing novel glassy Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(97-x-y)</sub> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> (x=5 -13, y=7-15) alloys for an inductor material with high corrosion resistance by added Cr is 1 at%. The glassy alloy series of Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(97-x-y)</sub> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cr (x=5-13, y=7-15) have high glass-forming ability with wide range super-cooled liquid region of 29-37 K, large critical thickness of 110-150 ¿m, and low coercivity of 2.5-3.1 A/m caused by the structural homogeneity. The Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">77</sub> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sub> Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> glassy alloy exhibits the largest critical thickness of 150 ¿m related to the wide super-cooled liquid region of 36 K and the high saturation magnetic flux density (Bs) of 1.3 T, both of which are higher than those of the conventional amorphous Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">75</sub> Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> Cr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> alloy. The Fe-P-B-Nb-Cr powder/resin composite core has much lower core loss of 650 kW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> which is approximately 1/3 lower than the conventional amorphous Fe-Si-B-Cr powder/resin composite core annealed at 623 K. Additionally, The Fe-P-B-Nb-Cr glassy alloy has higher corrosion resistance than other system glassy metal of Fe-Si-B-Nb-Cr by having a thick chromium passivation layer. the optimum annealing temperature of 623 K for these glassy alloys is lower than that (723 K) for the ordinary Fe-Si-B-Cr amorphous alloy, which is a significant advantage for the efficiency in mass production of inductor core using soft magnetic glassy alloy powder.

Self-assembly of three-dimensional Au inductors on silicon

Integration of inductors into high-frequency silicon circuits currently comes at the expense of a low-quality factor (Q), mainly because of electromagnetic interactions with the underlying substrate. Various fabrication methods for high Q inductors have been proposed, but poor compatibility with standard semiconductor process technology is a common problem. A promising technique involving in-plane fabrication and surface tension self-assembly to the vertical orientation has been previously reported for copper inductors. Here, a complementary metal–oxide–semiconductor (CMOS)-compatible and lead-free version of this process, with improved reproducibility, is reported, using Au as the inductor material. A 4 nH meander inductor is fabricated and tested as a demonstrator, showing significant increase of Q upon rotation.

Co2Z hexagonal ferrites for multilayer inductors

Z type Ba3Co1·4Fe24·6O41 for multilayer inductor applications at high frequency (up to 2 GHz) was prepared by a standard ceramic route. Single phase Z type ferrite is obtained at 1300°C. Dense samples sintered at 1300°C display a permeability of μ=30 throughout the megahertz range and a maximum μ″ at 0·5 GHz. The addition of Bi2O3 shifts the temperature of maximum shrinkage down to 900°C. Dense samples were obtained after sintering at 900°C; however, their permeability is only μ=5, but the maximum μ″ is at 2 GHz. It is shown that Co2Z ferrite is not stable at T<1300°C and that partial decomposition causes a reduction of permeability. Ferrite tapes were prepared by tape casting, and multilayer structures were fabricated by screen printing, stacking, lamination and cofiring. Firing was performed at 1300, 1000 and 900°C, i.e. at high and low temperature ceramic cofiring conditions respectively. It is shown that Co2Z hexagonal ferrites are suitable materials for multilayer inductors, although those prepared at 900°C suffer from lower permeability.

Fabrication of a Planar Inductor Using a Thick-Film Magnetic Metal Particle/Non-magnetic Material Composite for Micro Power Supply

In a previous study, a thick-film Mn-Zn ferrite particle/polyimide composite material for power inductors was developed using screen printing technique. This composite film enabled us to obtain a thin planar power inductor. However, downsizing of the planar inductor required that Mn-Zn ferrite particles be replaced by other magnetic particles with the higher permeability. In this study, we used two powdery magnetic metals to create a thick-film composite material, and fabricated downsized planar inductors using such composites. When used in a step-down chopper dc-dc converter, the fabricated inductors exhibited electric properties equal to those of competitive ready-made inductors, which are thicker than our planar inductor.

Fabricating Devices Using Nano-Particulates with Direct Write Technology

Nano-particulates are being used in conjunction with Direct Write Technologies for fabrication of electronic devices, sensors, and in tissue engineering. The materials being used in Direct Write Technologies predominately are suspensions, solutions or pastes comprised from nano-particulate metals, oxides or organics. This paper will present a comparison of several nano-particle silver inks being evaluated for use by one of these Direct Write Technologies, Maskless Meso-Scale Material Deposition (M3D) being developed by Optomec, Inc., Albuquerque, NM. USA. The silver inks in this case were deposited by the M3D process and then cured by sintering by both oven and by laser. Optical microscopy and Scanning Electron Microscopy (SEM) were used to examine the resultant cured material. The surface resistivity of these deposits was determined as a measure of their quality. A soft magnetic inductor material was also fabricated through a combination of nickel and iron oxide nano-particles. The results obtain with this inductor material are also discussed.

Model to determine the self-resonant frequency of micromachined spiral inductors

This letter presents an approach to characterize electron behaviors within polygonal micromachined spiral inductors in which self-resonance occurs. Combining with the concepts of anomalous dispersion, standing wave, and field scattering, the self-resonant frequency of the microinductors can be calculated by means of an associated analytical model. According to this model the self-resonant frequency (SRF) can be derived as the “free electron” frequency of the inductor material. Simulation and measurement results validate that the model can provide a satisfactory prediction to the SRF of polygonal micromachined spiral inductors.

High-frequency resistivity of soft magnetic granular films

Co-Zr-O granular films were prepared by reactive sputtering. The films show strong uniaxial in-plane anisotropy as well as good soft magnetic properties and high dc resistivity. In order to confirm their electrical characteristics at high frequency, the frequency and current density dependences of resistivity were investigated. Resistivity was found to be constant over the range measured (up to 18 MHz and 100 MA/m/sup 2/). Furthermore, the films exhibit virtually no hysteresis along the hard-axis direction and have very little anisotropy dispersion. The frequency dependence of the initial permeability was measured and used to predict the power loss expected when granular films are used as high-frequency core materials for film inductors. The power loss is predicted to be lower than that of commercial NiZn ferrite for high-frequency applications.

Low-loss inductors built on PECVD intrinsic amorphous silicon for RF integrated circuits

The quality factor (Q) of inductors on silicon (Si) is limited by the series resistance of the metal at low frequency and by the substrate resistivity at high frequency. Oxide is generally used to isolate the useful signal of the inductor from the lossy substrate. However, stoichiometric silica (SiO2) is processed at a high temperature, which eliminates the possibility of post-CMOS integration. By contrast, plasma enhanced chemical vapour deposition (PECVD) amorphous Si can be deposited at a low temperature and is easily integrated with most Si-based processes. Intrinsic amorphous hydrogenated silicon (i-a-Si:H) also displays low conductivity. In this work, i-a-Si:H deposited at a low temperature (250'C) is used in a novel approach as the isolation material for planar inductors on Si for RF integrated circuits. An improvementof more than 50% in Q is measured when 1.5 µm i-a-Si:H film is deposited on the Si substrate prior to fabrication of the inductor. This result demonstrates the influence of i-a-Si:H film on the RF performance of an inductor. Intrinsic a-Si:H is shown to be a promising material for the isolation of RF devices on low-resistivity Si.

Comparison of Magnetic Materials for V-Groove Inductors in Optimized High-Frequency DC-DC Converters

The tradeoff between saturation flux density and resistivity in soft magnetic materials for thin film inductors is examined quantitatively. We use an optimization routine to evaluate the achievable efficiency and power density using designs individually optimized to make best use of particular materials. The optimization selects switching frequency, ripple ratio, inductor dimensions and MOSFET sizes. For the example application of a 3.3- to 1.1-V, 7-A output dc-to-dc converter, Co-Zr-O, Fe-Al-O and Co-Fe-B-Si-O materials are considered. Predicted efficiencies are in the range of 80% to 90% at power densities of 20 W/cm/sup 2/ to 1000 W/cm/sup 2/. Different materials show advantages in different power-density or efficiency ranges.

Nonlinear Magnetic Properties of Mn-Modified Ba&amp;lt;tex&amp;gt;$_3$&amp;lt;/tex&amp;gt;Co&amp;lt;tex&amp;gt;$_2$&amp;lt;/tex&amp;gt;Fe&amp;lt;tex&amp;gt;$_23$&amp;lt;/tex&amp;gt;O&amp;lt;tex&amp;gt;$_41$&amp;lt;/tex&amp;gt;Hexaferrite

We have investigated the structural and magnetic properties of a novel type of hexaferrite with composition of Ba/sub 3/M/sub 2/Fe/sub 23/O/sub 41/ (where M=Co and Mn) (Z hexaferrite) with tunable permeability. The material is promising for very high frequency (VHF) control when used in a voltage-controlled oscillator (VCO) as a tunable inductor. We substituted Mn for Co in the composition Ba/sub 3/Co/sub 2-x/Mn/sub x/Fe/sub 23/O/sub 41/ from x=0.0 to 1.2 to improve the inductance tunability and quality factor of the inductor material. Mn substitution had significant influence on the grain size of the sintered hexaferrites, and the coercivity was greatly reduced. The initial permeability and quality factor increased with increasing substitution of Mn for Co until x reached 0.5, an effect attributed to the decrease of the magnetocrystalline anisotropy constant of the hexaferrite and increase of average grain size. The tunability of the samples also increased with increasing Mn substitution, reaching a maximum at x=0.5, and then decreased with further substitution. This behavior is similar to that of the initial permeability and coercivity, and can be explained by the same mechanism.

Ｙ型六方晶フェライトの低温焼成化及び高透磁率化

Low-temperature sintering Y-type hexagonal femtes were made by the ceramics method. The temperature obtaining a single phase shifted lower with the CuO content. In Ba2Co1.0Cu1.0Fe12O22, a single phase was obtained at 950°C calcination. At the same time, the shrinkage curve shifts to the low temperature, and the firing temperature that is able to get over 95% of the theoretical density has lowered from 1200°C to 1000°C by the CuO substitution. Further more, Bi2O3 addition shifted the shrinkage curve to the low temperature. Exact sintered body with 900°C sintering was obtained by 5 wt% addition. The permeability and resonance frequency were 2.3 and 5.7 GHz respectively. The permeability was improved by divalent metal substitution, Ba2Me1.0Cu1.0Fe12O22 (Me: Ni, Mg, Zn), and the highest permeability was achieved by Zn substitution. The permeability and resonance frequency were 9.7 and 1.0 GHz respectively. It is found that Ba2ZnxCu2-xFe12O22 with Bi2O3 addition show high performance as magnetic material for chip inductors.

Development of High Permeability Core Materials for Embeddable Inductors in Flexible Organic Substrates

AbstractCapacitors, resistors and inductors are surface mounted components on circuit boards, which occupy up to 70% of the circuit board area. For selected applications, these passives are packaged inside green ceramic tape substrates and sintered at temperatures over 700°C in a co-fired process. These high temperature processes are incompatible with organic substrates, and low temperature processes are needed if passives are to be embedded into organic substrates. A new high permeability dual-phase Nickel Zinc Ferrite (DP NZF) core fabricated using a low temperature sol-gel route was developed for use in embedded inductors in organic substrates. Crystalline NZF powder was added to the sol-gel precursor of NZF. The solution was deposited onto the substrates as thin films and heat-treated at different temperatures. The changes in the microstructures were characterized using XRD and SEM. Results showed that addition of NZF powder induced low temperature transformation of the sol-gel NZF phase to high permeability phase at 250°C, which is approximately 350°C lower than transformation temperature for pure NZF sol gel films. Electrical measurements of DP NZF cored two-layered spiral inductors indicated that the inductance increased by three times compared to inductors without the DP NZF cores. From microstructural observations, the increase is correlated with the changes in microstructural connectivity of the powder phase.

Electric and Magnetic Properties of a New Ferrite-CeramicComposite Material

We have investigated a new ferrite-ceramic composite material with inductiveand capacitive properties fabricated by a solid-state reaction method. We analysethe effects of the composite mechanism and microstructure on the magnetic andelectric properties. The results show that the new materialscan be used not only as inductor materials, but also as capacitormaterials in the wide frequency range of 1 kHz-1.8 GHz. The real part ofpermeability of the composite material is between 10 and 5.6, the imaginarypart of permeability is between 1.2 and 0.5, and the dielectric constantis about ten times larger than that of ordinary ferrite materials. It is suggestedthat the new composite materials will be widely used in anti-electromagneticinterference fields and radio frequency communication fields

Properties of high resistivity CoPdAlO film for possibility of application to RF integrated inductor

Presently, an inductor adapted at MMIC (Monolithic microwave integrated circuit) which is used for cellular phone or PHS operates at quasimicrowave range over 800 MHz. However, a W-CDMA (Wideband code division multiple access) will use about 2 GHz range. Therefore magnetic film devices should be compatible up to 2 GHz. We deposited Co-Pd-Al-O system film using rf sputtering method which is expected for operating at 2 GHz, and investigated the effect of Pd content and magnetic field annealing. When Pd composition is 19%, H/sub k/ was 118 Oe, and showed flat frequency characteristics until 1.5 GHz. The Q factor (=/spl mu/'//spl mu/) was 23.3 at 1 GHz, 6.7 at 1.5 GHz and 1.5 at 2 GHz, respectively. Resonance frequency was 2.9 GHz, therefore Co-Pd-Al-O thin film could be used at over 1 GHz, and also expected as an inductor material for next generation MMIC.

Maxillofacial surgical application of bone inductor materials.

Maxillofacial surgical application of bone inductor materials.

Application of Bone Morphogenetic Proteins in the Treatment of Clinical Oral and Maxillofacial Osseous Defects

Commonly occurring extensive osseous defects in the oral and maxillofacial area are seen following complete or partial resection of the mandible and other facial bones in oncologic surgery or following traumatic injury. Autogenous osseous grafts have been used to restore these defects. Additionally, bone graft substitute materials and autogenous osseous grafts are applied to congenital defects such as cleft palate, facial clefts, and facial asymmetry. We have simulated these types of defects in appropriately aged Macaca fascicularis and Macaca mulatta monkeys to study the efficacy of using bone morphogenetic protein (BMP) as an osseous inductor. The objective of these studies was to obtain information on the feasibility of employing bone inductors to regenerate large continuity critical-sized maxillofacial defects without using bone grafts. In one study, involving eight animals, the body of the mandible was removed, simulating hemi-mandibulectomy defects following traumatic bone loss or oncologic surgery. Recombinant human (rh) BMP-2 (Genetics Institute, Cambridge, Massachusetts) in a collagen carrier (Colla-Tec Inc., Plainsboro, New Jersey) then was placed in the hemi-mandibulectomy defect with use of titanium orthopaedic mesh fixation (Sofamor Danek-Medtronic, Memphis, Tennessee). Entire bone regeneration of the defect was observed 5 and 6 months postoperatively. In another group of subhuman primates, the restored area was functionally stimulated at the 5-month post-BMP implantation level by placement of intraoral titanium implants. The animals were allowed to function for 8 months with these titanium implants. Microscopic results showed increased density, bone volume, and thickness of the trabecular bone pattern. The bone cortex in the restored defect also increased in thickness compared with the nonsurgical areas. To evaluate the effect of rhBMP-2 in aging individuals, a group of six Macaca animals over 20 years of age received the same type of mandibular resection followed by BMP grafting with functional stimulation by mastication on root form implants placed at 5 months after BMP implantation. The entire mandible regenerated as in the younger group of animals; therefore, age did not appear to be a factor in the reparative process. Thus, the number of stem cells supposedly reduced with increasing age did not appear to affect the overall result of BMP-induced bone regeneration. Additionally, in applying the inductor material to younger monkeys (1-1 1/2 years of age), the rhBMP-2 was placed in simulated bilateral cleft palate defects. On one side, the rhBMP-2 was placed with use of the collagen sponge carrier. The autogenous graft most frequently used at present for regeneration of the osseous defects of maxillary clefts is iliac crest particulate cancellous bone. As a control graft on the contralateral side, therefore, autogenous particulate bone and marrow was placed. At the end of 3 months, the cleft side receiving the BMP-2 showed complete osseous restoration of the simulated cleft. The autogenously grafted side exhibited bone repair but incomplete regeneration of the bone defect at the early (3-months postoperative) stage of healing. The results of these three subhuman primate defect studies--(a) mandibular resection defects in middle-aged Macaca fascicularis animals, (b) mandibular resection defects in Macaca fascicularis animals over 20 years of age, and (c) simulated bilateral clefts in Macaca mulatta animals 1 1/2 years of age (comparable with a 5-year-old child)--were very encouraging. Histomorphometric analysis in all of these investigations indicated that the use of rhBMP-2 in bone repair without the use of bone grafting materials will offer a new method of osseous reconstruction in clinical facial bone defects.