Core-shell parylene coating for improving wire bonding stiffness and damping with cost effectiveness

Abstract

Wire bonding is performed between a first surface and a second surface of an electronic package having a lead assembly. A core layer is applied to the lead to surround it, wherein the core layer has a first density. A shell layer is applied to the core layer to surround it, wherein the shell layer has a second density. The first density is less than the second density.

Description

Cross-references to related applications

[0001] This application claims the benefit of the earlier filing date of U.S. Provisional Application Serial No. 63 / 556,152, filed on February 21, 2024. Background Technology

[0002] In the resource recycling industry, drill strings are used to drill boreholes into formations. A drill string comprises a drill bit for drilling into the formation and an electronic system for controlling various aspects of the drilling operation. The electronic system consists of multiple electronic modules. Wire bonding interconnects are used in various applications within electronic packages, such as connecting substrates or printed circuit boards to pins for electrical connections with tool wiring and other electronic modules. As the drill bit rotates to drill a borehole, shocks and vibrations caused by drilling can be transmitted along the drill string. Exciting wire bonds at their intrinsic frequencies due to the high quality factor of these resonances shortens their lifespan. To increase the durability of wire bonds, the stiffness of the bond can be increased, the amplitude of its oscillations reduced (i.e., its damping increased), or the local mechanical stability increased at locations where fracture typically occurs (e.g., at the wire bond heel). A single-layer coating can be applied to protect the wire bonds, increasing their durability and providing limited protection. Typically, thicker coatings will be required, increasing manufacturing costs and time. Additional coatings of different coating materials can be used to adjust coating properties. However, the complexity of the manufacturing process, manufacturing time, and cost increase with each additional coating material. Since both conventional single-coat and multi-coat methods have drawbacks, an alternative, cost-effective manufacturing process is needed. Summary of the Invention

[0003] This document discloses an electronic package including a lead assembly. The lead assembly includes: a lead bonded between a first surface and a second surface; a core layer surrounding the lead and having a first density; and a shell layer surrounding the core layer. The shell layer has a second density, wherein the first density is less than the second density.

[0004] This document also discloses a method for manufacturing an electronic package including a lead assembly. The method includes: bonding a lead between a first surface and a second surface; applying a core layer to the lead to surround the lead, wherein the core layer has a first density; and applying a shell layer to the core layer to surround the core layer, wherein the shell layer has a second density, and wherein the first density is less than the second density. Attached Figure Description

[0005] The following description should not be considered as limiting in any way. Referring to the accompanying drawings, the same element numbers are used:

[0006] Figure 1 A drill string is shown in an exemplary embodiment;

[0007] Figure 2 An electronic module that can be used at the downhole device of the drill string is shown;

[0008] Figure 2A An internal cross-sectional view of the electronic device module is shown;

[0009] Figure 3 A side view of the bonding wire is shown;

[0010] Figure 4 A table showing the fundamental intrinsic frequencies of different lead coating configurations is provided.

[0011] Figure 5 A cross-sectional view of a core-shell coated lead is shown in one embodiment;

[0012] Figure 6 A flowchart of a method for coating leads is shown; and

[0013] Figure 7 The deposition timeline of the core-shell layer of the lead is shown. Detailed Implementation

[0014] Specific embodiments of one or more implementations of the devices and methods disclosed herein are presented by way of example rather than limitation, with reference to the accompanying drawings.

[0015] refer to Figure 1An exemplary embodiment illustrates a drilling system 100 including a drill string 102. While a land-based drilling rig is shown, these concepts and methods are equally applicable to offshore drilling systems. The drill string 102 can be suspended from the drilling rig 104 and may include a connecting fitting 106 or coiled tubing for drilling a borehole 108 in a rock formation 110. The drill string 102 includes an inner bore to allow drilling fluid to flow from a surface location 105 to a drill bit 112 located at the bottom of the drill string 102 and back to the surface through the annulus between the borehole 108 wall and the drill string 102. The drill string 102 includes a bottom hole assembly (BHA) 114 above the drill bit 112. In one configuration, the BHA 114 includes the drill bit 112 and downhole tools. Downhole tools may be a sensor connector 116, a two-way telemetry device 118, a formation assessment (FE) device 120, a steering unit 122, and a rotary power unit, such as a drilling motor 124. Sensor connector 116 may include sensors for measuring near-bit orientation (e.g., BHA azimuth and dip, BHA coordinates, etc.) and sensors and tools for rotational orientation surveying. Drilling system 100 may also include information processing devices such as surface controller 126 and / or downhole controller 128. Communication between surface location 105 and BHA 114 may use uplinks and / or downlinks generated by mud-driven telemetry devices (such as mud pulse generators) and / or transmitted using hardwired (e.g., electrical conductors, optical fibers), acoustic signals, EM, or RF transmissions. One or more electronic modules 130 incorporated into BHA 114 or other components of drill string 102 may include components necessary for data storage and processing, communication, and / or control of BHA 114. These components may be housed in suitable compartments formed in or on drill string 102. Exemplary electronics in the electronic modules include printed circuit board assemblies (PCBAs) and multi-chip modules (MCMs).

[0016] Figure 2 An electronic module 200 is shown that can be used at the downhole device 106 of the drill string 100. The electronic module 200 includes a housing 202 and a pin portion 204 through which it can be connected to external devices. Figure 2AAn internal cross-sectional view 210 of the electronic device module 200 is shown. The housing 202 includes an electronic package 212 comprising a substrate 214 and a die 216 attached to the substrate 214. The electronic package 212 may include a chip assembly or other electronic device. Bonding leads 218 form connections between the substrate 214 and the pins of the lead portion 204 of the housing 202. Bonding leads are typically made of gold, copper, silver, aluminum, or alloys such as aluminum alloys. Another bonding lead 220 connects the substrate to the pins on the die 216. Although only one bonding lead 218 connecting the substrate 214 to the lead portion 204 of the housing 202 is shown, it should be understood that multiple leads can be used to form multiple connections between the substrate 214 and the pins of the lead portion 204 of the housing 202. Additionally, multiple bonding leads 220 may be present connecting the substrate 214 to the die 216. Figure 2AThe electronic device module in the MCM can be a multi-chip module (MCM). The MCM uses a ceramic substrate to construct the circuit board and includes electronic components. These electronic components can be active or passive. In some embodiments, the electronic components can be constructed on or within the ceramic substrate. The electronic components are constructed from semiconductor materials (such as silicon and / or germanium) or alternative materials capable of withstanding temperatures up to 150°C to 175°C, 175°C to 200°C, 200°C to 225°C, 225°C to 250°C, or 250°C to 275°C. MCMs used in high-temperature applications can avoid the use of organic materials. Semiconductor components are typically not soldered to the metallization region of the ceramic substrate, but are interconnected via wire bonding or the use of adhesives. Semiconductor components can be wire-bonded to the substrate as so-called "bare dies." Wire bonding is a soldering technique that does not use flux materials. The coefficient of thermal expansion can be considered when selecting materials to construct the electronic components to be bonded to the ceramic substrate. The electronic components are attached to at least one side of the ceramic substrate. In an alternative embodiment, the electronic components are attached to both sides (front and back) of the ceramic substrate. The MCM is encapsulated in a housing to protect the substrate and the electronic components from environmental influences that could cause degradation of the materials used in the MCM (ambient gases, such as those originating from potting materials, solder, insulating materials, or organic materials used in polymer seals). In many applications, the MCM housing is hermetically sealed by using welding techniques to close the housing or by using metal seals. In downhole applications, the electronic board, including a circuit board, can be located within a cavity in a collar closed by a hatch or sleeve in a downhole tool. Alternatively, the circuit board can be located within a container inside the bore of a downhole tool (probe-based downhole tool) through which drilling fluid flows downhole. The electronic board (with or without a housing) can be securely attached to the inside of the downhole tool (collar, container in the bore (probe), megaframe) using fastening members, which can be screws, adhesives, or clamps. The fastener may include a biasing member, such as a spring or elastomeric material, which may be located somewhere within the cavity containing the electronic board or electronic housing. The biasing member compensates for vibrations and shocks generated during downhole operation of the downhole tool.

[0017] Figure 3 A side view 300 of the bonding lead 218 is shown. In various embodiments, the bonding lead 218 may be a cylindrical lead or a strip. The bonding lead 218 extends from point A at the lead portion 204 (first surface) to point B at the substrate 214 (second surface), forming an arc between the two. Point A is located at a height h above point B. The horizontal distance between points A and B is represented by x. The vertical height h of the lead is measured between point B and the top of the arc of the bonding lead 218. w The length of the bonding wire 218 is determined by l wFor illustrative purposes, the height h is 2.2 mm, the horizontal distance x is 5.0 mm, and the vertical height h is... w It is 2.5mm, and the lead length is l w The bonding wire 218 is 5.8 mm long. At connection point A or B, common wire bonding techniques (such as ball bonding, wedge bonding, or flexible bonding) are used to weld the bonding wire 218. At each connection point, the wire bond forms a heel 222. Simulations of this strip-shaped wire show that it resonates at a frequency of approximately 2.7 kHz (resonant frequency or intrinsic frequency). Resonant excitation does not occur at frequencies significantly lower or higher than this resonant frequency. The resonant frequency (~2.7 kHz) is within the frequency range of oscillations along the drill string 100, originating from the cutting process of the rock formation. The vibration can be a high-frequency torsional oscillation (HFTO) typically above 50 Hz. Therefore, the bonding wire 218 is prone to breakage because vibrations in the drill string 100 occur at or above this resonant frequency (higher-order resonant modes). In one embodiment, the resonant frequency of the bonding wire can be between 1 kHz and 3 kHz, between 2 kHz and 5 kHz, or between 2 kHz and 10 kHz.

[0018] In various embodiments, a coating may be deposited on the bonding lead 218 to shift the initial intrinsic frequency of the bonding lead 218 to a final intrinsic frequency that is higher than the initial intrinsic frequency and outside the range of vibration frequencies along the drill string 100. The coating may be made of parylene. The initial intrinsic frequency or initial resonant frequency refers herein to the bonding lead without any coating.

[0019] Figure 4 Table 400 shows the intrinsic frequencies of different examples of bonding lead coating configurations. The different coating configurations include bonding leads without any coating, bonding leads with a first coating (core layer), and bonding leads with a first layer (core layer) and a second layer (shell layer). These examples are given for illustrative purposes and do not limit the generality of the method. The frequencies in Table 400 were obtained from finite element simulations of different bonding lead coating configurations. Table 400 includes a first column 402 of intrinsic frequencies (initial intrinsic frequencies) for uncoated leads (uncoated bonding leads), a second column 404 of intrinsic frequencies for coated bonding leads with only a core layer, a third column 406 of intrinsic frequencies for shell layers without conductors and without a core layer, and a fourth column 408 of intrinsic frequencies for coated leads with both a core layer and a shell layer. In this example, the bonding lead itself has a strength of 19.3 g / cm³. 3 It has a density (of gold), a Young's modulus of 95 gigapascals (GPa), and a Poisson's ratio of 0.44. The core layer (second column 404) has a density of approximately 0.5 g / cm³. 3 Up to 1.3 g / cm3 The density of the shell (third column) is 1.5 g / cm³. 3 Up to 1.8 g / cm 3 The density. The material properties of the shell typically correspond to a density of 1.7 g / cm³. 3 The material properties of porosilicate with a Young's modulus of 3.0 GPa and a Poisson's ratio of 0.35 are described. Again, these properties are merely illustrative and do not limit the method to a particular type of bonding lead coating material. The coating material can be parylene F, which is preferred for high-temperature applications. In an alternative embodiment, the coating material can be parylene C or parylene N. In another embodiment, the core layer can be made of parylene C, and the shell layer can be made of parylene F. Parylene C is relatively inexpensive but unstable at high temperatures. However, covering the parylene C core layer with a high-temperature stable parylene F shell layer protects the core layer from chemical reactions at high temperatures. Using a parylene C core layer reduces the cost of the bonding lead assembly. In another embodiment, polyurethane foam is used for the core layer, and a polyurethane coating agent is used for the shell layer. Other materials are also feasible (e.g., silicone resin), as long as these materials are non-conductive and layers with different densities can be applied to the bonding leads. Combinations of materials are generally possible, provided there are no undesirable chemical reactions. That is, the core layer is made of one material, and the shell layer is made of a second material (e.g., the core layer is parylene, and the shell layer is a ceramic material or a metal (gold, aluminum)). In another embodiment, a thin layer made of a third material separates the core layer and the shell layer. The third material can be titanium oxide, zirconium oxide, or hafnium oxide. The third layer can be deposited on the second layer by atomic layer deposition (ALD). The density of the third layer is higher than that of the first layer.

[0020] In the first column 402, the intrinsic frequency of the uncoated 50 μm thick bonding lead is approximately 2.7 kHz. In the second column 404, the intrinsic frequency of the first oscillation mode of the bonding lead coated with a 250 μm thick parylene core layer is approximately 12.5 kHz. The intrinsic frequency of the first mode of a thin hollow parylene shell or tube (third column 406, shell thickness 15 μm) having the same outer diameter (550 μm) as the configuration in column 404 and the same length distribution as the initial bonding lead has an intrinsic frequency of approximately 11.3 kHz. Both the 250 μm thick parylene core layer (404) and the thin parylene shell layer (406) raise the intrinsic frequencies of the corresponding oscillation modes to similarly high values ​​(i.e., 12.5 kHz and 11.3 kHz for the first mode, respectively). The damping characteristics achieved using conventional methods are not optimized compared to those achieved using the methods disclosed herein. Therefore, the core-shell coating disclosed herein reduces manufacturing time and provides excellent damping. Conventional deposition rates for the void-free, high-quality parylene layer used for the shell are 3 μm per hour or 5 μm per hour, depending on process parameters. For the core-shell configuration (4th column 408), the core layer comprises a 235 μm thick parylene layer with a lower density than the shell layer and contains numerous vacancies or voids. The core layer is deposited on a 50 μm thick bonded lead by applying the coating at a deposition rate much higher than conventional deposition rates. The deposition rate of the void-rich, low-quality parylene core layer can be much faster than that of the high-quality shell layer. Typically, the deposition rate is two to ten times that of conventional deposition rates. In one embodiment, the deposition rate of the void-rich parylene core layer can be 20 times that of conventional deposition rates. The shell layer comprises a conformal 15 μm thin parylene coating and is deposited using deposition parameters suitable for achieving a substantially void-free layer. For this simulation, the core layer has a density of 0.6 g / cm³. 3 The density, Young's modulus of 0.8 GPa, and Poisson's ratio of 0.18 are all present. Because the core layer can be deposited rapidly, the total deposition time for the core-shell configuration is less than that required to deposit a single-layer coating with the same thickness (core thickness plus shell thickness) as the core-shell configuration. The porous and low-density core increases the damping of excitation oscillations (vibrations) of the bonding leads. Therefore, the eigenfrequency of the core-shell structure was found to be approximately 11.7 kHz (column 4, 408). Figure 4 The table shows that a shift of the intrinsic frequency to a higher frequency can be achieved by applying a thick layer of parylene (250 μm) on the bonding leads. The main increase in frequency shift is achieved by applying a core layer (in...) Figure 4 This is achieved using a core layer (referred to as a "low-density" layer), which increases the mass of the leads while still ensuring flexibility due to the porosity in the parylene material. Figure 4The void-free shell, referred to as the "full-density" layer, stabilizes the bonded leads surrounded by the core layer. Simultaneously, the shell protects the bonded leads from potentially harmful substances. It can be observed that the shell has little effect on the intrinsic frequency shift. Parylene is typically applied to the bonded leads via vapor deposition at a low deposition rate. Applying a sufficiently thick void-free parylene layer to achieve the same intrinsic frequency shift is economically impractical. However, applying a void-rich parylene layer allows for much faster deposition rates, such as two to twenty times that of void-free parylene layers. Void-rich parylene layers are unsuitable for bonded leads using chemically isolated parylene coatings. Surrounding a thick, void-rich core layer with a thin, void-free parylene layer provides the necessary chemical isolation. The bonded leads, surrounded by a core layer which is then surrounded by a shell layer, define a bonded lead assembly with a shifted intrinsic frequency compared to uncoated bonded leads.

[0021] Figure 5 A cross-sectional view 500 of a core-shell coated lead is shown in one embodiment. The coated lead includes a lead 502 (e.g., a bonding lead 218), a first material layer 504 surrounding the lead 502, and a second material layer 506 surrounding the first layer 504. The first layer 504 and the second layer 506 form a core-shell structure having a flexible core and a rigid shell. In one embodiment, the lead 502 has a diameter of about 50 micrometers (μm). The first layer 504 and the second layer 506 are made of parylene. The first layer 504 has a thickness d1 of about 235 μm. In another embodiment, the thickness of the first layer 504 is in the range of about 40 μm to about 250 μm. In one embodiment, the thickness of the first layer is in the range of about 50 μm to about 300 μm. In another embodiment, the thickness of the first layer is in the range of about 100 μm to about 200 μm. The second layer 506 has a thickness d2 of about 1 μm to about 15 μm. In another embodiment, the thickness of the second layer 506 is in the range of about 5 μm to about 20 μm. In yet another embodiment, the thickness of the second layer is in the range of about 1 μm to about 50 μm.

[0022] In one embodiment, the first layer 504 and the second layer 506 are formed by chemical vapor deposition of parylene onto the lead 502. The parylene dimer is heated, and the vapor decomposes to produce parylene monomer vapor, which polymerizes on the target surface during condensation. To form the first layer 504, the parylene vapor is heated to a first temperature T1 ranging from about 110°C to about 200°C at a pressure of about 20 Pascals. The first layer 504 is deposited at a first deposition rate, which is a high deposition rate. During deposition at the first deposition rate, voids are formed in the layer. Therefore, the first layer 504 has a porous, foam-like structure. In one embodiment, the first layer 504 has a density of about 0.6 g / cm³. 3 It has a thin thickness and low stiffness due to its foam structure.

[0023] To form the second layer, a parylene source is heated at a second temperature T2 below the first temperature and a pressure less than about 10 Pascals to generate parylene vapor. Parylene is deposited on the first layer 504 at a second deposition rate less than the first deposition rate. Due to the slow deposition rate, parylene is deposited as a high-quality, dense, conformal film. Therefore, the resulting second layer 506 forms a rigid shell with high stiffness. The first layer 504 has a first density, and the second layer 506 has a second density greater than the first density. The density of the first layer 504 is at least 30% less than the density of the second layer 506 (i.e., the density of the first layer is between 0% and 70% of the density of the second layer). In one embodiment, the density of the first layer is at least 20% less than the density of the second layer. In another embodiment, the density of the first layer is at least 15% less than the density of the second layer. In yet another embodiment, the density of the first layer is at least 10% less than the density of the second layer.

[0024] Individually (i.e., without the parylene coating), the lead has a first resonant frequency excited by a first range of vibrational frequencies excited by the drilling process. In one embodiment, the resonant frequency of the bonded lead can be between 1 kHz and 3 kHz, between 2 kHz and 5 kHz, between 2 kHz and 10 kHz, or between 2 kHz and 20 kHz. The resonant frequency (intrinsic frequency) can be the fundamental resonant frequency (intrinsic intrinsic frequency). Adding the first layer (core layer) 504 suppresses the amplitude of the excited oscillation mode and typically increases the resonant frequency of the bonded lead from the first resonant frequency to a second resonant frequency greater than the first resonant frequency. Adding the second layer (shell layer) 506 has little effect on the resonant frequency.

[0025] In other words, the intrinsic frequency has a first value for a first lead assembly having only lead 502, a second value for a second lead assembly having a combination of lead 502 and first layer 504, and a third value for a third lead assembly having a combination of lead 502, first layer 504, and second layer 506. The second value is greater than the first value. Furthermore, the second and third lead assemblies have greater stiffness and tensile strength than the first lead assembly. Additionally, compared to the first lead assembly, the second and third lead assemblies reduce strain at the bonding site (heel). Adding a second layer (shell) 506 with a first high-density material stabilizes (i.e., increases stiffness) and protects the bonded leads covered by the first layer 504, which has a second density less than the first density. The second layer 506 has greater stiffness than the first layer 504. Due to its porous structure, the first layer 504 is flexible. The flexibility of the first layer has a significant damping effect on the oscillations of the bonded leads. The damping effect of a material is indicated by the quality factor of its resonance curve. Bonded leads without any coating or with only a thick conventional coating have a much higher quality factor than bonded leads with applied core and shell layers. This damping effect, combined with a resonant frequency shift to higher frequencies and away from the range typically excites oscillations in downhole operations, reduces the number of failures caused by broken bonded leads. The damping effect and the resonant frequency shift are primarily achieved by the first layer 504. In one embodiment, the bonded lead assembly may consist only of the first layer 504. The primary reason for applying a void-free second layer is that chemical protection of the bonded leads may not be adequately provided due to the low quality of parylene in the first layer 504. However, alternative measures can be used to avoid chemical degradation of the bonded leads, such as operations in a chemical isolation chamber. In this case, the second layer 506 can be omitted.

[0026] Figure 6A flowchart 600 for a method of coating leads is shown. In block 602, parylene dimer is heated to a first temperature T1. A pyrolyzer pyrolyzes the dimer at a first chamber pressure P1 to produce parylene monomer vapor. In block 604, the parylene vapor is deposited and polymerized on the lead at a first deposition rate. In block 606, the parylene dimer is heated to a second temperature T2, lower than the first temperature, at a second chamber pressure P2, lower than the first chamber pressure P1, to produce parylene monomer vapor. In block 608, parylene is deposited on the lead (i.e., on the core) at a second deposition rate lower than the first deposition rate. Depositing parylene on the lead at the first deposition rate results in a lower density deposition of parylene, thus creating voids in the core layer. Depositing parylene vapor on the lead at the second rate forms a high-density (i.e., standard density parylene coating) deposition without forming virtually any voids (no voids). The result is that the shell is rigid relative to the flexible core.

[0027] Figure 7 The deposition timeline 700 for the core shell layer of the lead is shown. This layer is formed at a first deposition rate R1 during a first deposition time t1 and at a second deposition rate R2 during a second deposition time t2. A first layer 504 is formed during the first deposition time t1, and a second layer 506 is formed during the second deposition time t2. The first deposition rate R1 is greater than the second deposition rate R2. During the first deposition time t1, the parylene dimer is heated to a high temperature T1, as indicated by the first deposition rate line 702. During the second deposition time t2, the parylene dimer is heated to a lower temperature T2 (T1>T2), as indicated by the second deposition rate line 704. For comparison, a third deposition time t3 is shown, which represents the time required to deposit a layer with the same thickness as the core shell coating using only the deposition rate R2, as indicated by the third deposition rate line 706. The third deposition time t3 is longer than the sum of the first deposition time t1 (during which deposition is carried out at rate R1) and the second deposition time t2 (during which deposition is carried out at rate R2).

[0028] The following are some of the aforementioned publicly disclosed implementation schemes:

[0029] Implementation Scheme 1. An electronic package including a lead assembly is disclosed. The lead assembly includes: a lead bonded between a first surface and a second surface; a core layer surrounding the lead and having a first density; and a shell layer surrounding the core layer and having a second density, wherein the first density is less than the second density.

[0030] Implementation Scheme 2. The electronic package according to any of the foregoing embodiments, wherein the core layer is made of the same material as the shell layer.

[0031] Implementation Scheme 3. The electronic package according to any of the foregoing implementation schemes, wherein the material is parylene.

[0032] Implementation Scheme 4. An electronic package according to any of the foregoing embodiments, wherein the core layer is made of a first material, the shell layer is made of a second material, and the first material is different from the second material.

[0033] Implementation Scheme 5. An electronic package according to any of the foregoing embodiments, wherein the core layer is applied using vapor deposition at a first deposition rate, and the shell layer is applied using vapor deposition at a second deposition rate, wherein the first deposition rate is greater than the second deposition rate.

[0034] Implementation Scheme 6. The electronic package according to any of the foregoing embodiments, wherein the lead is part of a multi-chip module in a downhole tool.

[0035] Implementation Scheme 7. An electronic package according to any of the foregoing embodiments, wherein the lead has a first resonant frequency and the lead surrounded by the core layer has a second resonant frequency, wherein the first resonant frequency is less than the second resonant frequency.

[0036] Implementation Scheme 8. An electronic package according to any of the foregoing embodiments, wherein the core layer has a first thickness, the shell layer has a second thickness, and the first thickness is greater than the second thickness.

[0037] Implementation Scheme 9. The electronic package according to any of the foregoing embodiments, wherein the first thickness is one of the following: (i) at least ten times the second thickness; and at least five times the second thickness.

[0038] Implementation Scheme 10. An electronic package according to any of the foregoing embodiments, wherein the lead has a first resonance curve having a first quality factor, the lead assembly has a second resonance curve having a second quality factor, and the first quality factor is greater than the second quality factor.

[0039] Implementation Scheme 11. The electronic package according to any of the foregoing embodiments, wherein the first density is at least 10% smaller than the second density.

[0040] Implementation Scheme 12. A method for manufacturing an electronic package including a lead assembly is disclosed. The method includes: bonding leads between a first surface and a second surface; applying a core layer to the leads to surround the leads, wherein the core layer has a first density; and applying a shell layer to the core layer to surround the core layer, wherein the shell layer has a second density, wherein the first density is less than the second density.

[0041] Implementation Scheme 13. The method according to any of the foregoing embodiments, wherein the core layer is made of the same material as the shell layer.

[0042] Implementation Scheme 14. The method according to any of the foregoing implementation schemes, wherein the material is parylene.

[0043] Implementation Scheme 15. The method according to any of the foregoing embodiments, wherein the core layer is made of a first material, the shell layer is made of a second material, and the first material is different from the second material.

[0044] Implementation Scheme 16. The method according to any of the foregoing embodiments, the method further comprising applying the core layer using vapor deposition at a first deposition rate and applying the shell layer using vapor deposition at a second deposition rate, wherein the first deposition rate is greater than the second deposition rate.

[0045] Implementation Scheme 17. The method according to any of the foregoing embodiments, wherein the lead has a first resonant frequency and the lead surrounded by the core layer has a second resonant frequency, wherein the first resonant frequency is less than the second resonant frequency.

[0046] Implementation Scheme 18. The method according to any of the foregoing implementation schemes, wherein the core layer has a first thickness, the shell layer has a second thickness, and the first thickness is greater than the second thickness.

[0047] Implementation Scheme 19. The method according to any of the foregoing implementation schemes, wherein the first thickness is one of the following: (i) at least ten times the second thickness; and at least five times the second thickness.

[0048] Implementation Scheme 20. The method according to any of the foregoing implementation schemes, wherein the lead has a first resonance curve having a first quality factor, the lead assembly has a second resonance curve having a second quality factor, and the first quality factor is greater than the second quality factor.

[0049] Implementation Scheme 21. The method according to any of the foregoing implementation schemes, wherein the first density is at least 10% smaller than the second density.

[0050] In the context of describing the invention (particularly in the context of the appended claims), the terms “an” and “the”, and similar designations, should be interpreted to cover both the singular and the plural, unless otherwise specified herein or clearly contradicted by the context. The terms “about,” “substantially,” and “generally” are intended to include a degree of error associated with a specific number of measurements based on the equipment available at the time of filing. For example, “about” and / or “substantially” and / or “generally” can include a range of ±8% for a given value.

[0051] Although the invention has been described with reference to one or more exemplary embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted for elements therein without departing from the scope of the invention. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the invention without departing from the basic scope of the invention. Therefore, it is contemplated that the invention is not limited to the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but rather that the invention will encompass all embodiments falling within the scope of the claims. Additionally, exemplary embodiments of the invention have been disclosed in the drawings and detailed descriptions, and although specific terminology has been used, it is used in a general and descriptive sense only, and not for limiting purposes, unless otherwise specified; therefore, the scope of the invention is not limited thereto.

Claims

1. An electronic package including a lead assembly, the lead assembly comprising: Lead wires, said lead wires being bonded between the first surface and the second surface; A core layer that surrounds the lead wire, the core layer having a first density; and A shell layer surrounding the core layer, the shell layer having a second density, wherein the first density is less than the second density.

2. The electronic package according to claim 1, wherein, The core layer is made of the same material as the shell layer.

3. The electronic package according to claim 2, wherein, The material is parylene.

4. The electronic package according to claim 1, wherein, The core layer is made of a first material, the shell layer is made of a second material, and the first material is different from the second material.

5. The electronic package according to claim 1, wherein, The core layer is applied using vapor deposition at a first deposition rate, and the shell layer is applied using vapor deposition at a second deposition rate, wherein the first deposition rate is greater than the second deposition rate.

6. The electronic package according to claim 1, wherein, The lead wire is part of a multi-chip module in a downhole tool.

7. The electronic package according to claim 1, wherein, The lead has a first resonant frequency, and the lead surrounded by the core layer has a second resonant frequency, wherein the first resonant frequency is less than the second resonant frequency.

8. The electronic package according to claim 1, wherein, The core layer has a first thickness, the shell layer has a second thickness, and the first thickness is greater than the second thickness.

9. The electronic package according to claim 8, wherein, The first thickness is one of the following: (i) at least ten times the second thickness; and at least five times the second thickness.

10. The electronic package according to claim 1, wherein, The lead has a first resonance curve with a first quality factor, the lead assembly has a second resonance curve with a second quality factor, and the first quality factor is greater than the second quality factor.

11. The electronic package according to claim 1, wherein, The first density is at least 10% smaller than the second density.

12. A method of manufacturing an electronic package including a lead assembly, the method comprising: Wire bonding is performed between the first and second surfaces; A core layer is applied to the lead to surround the lead, wherein the core layer has a first density; and A shell is applied to the core layer to surround the core layer, wherein the shell layer has a second density, and wherein the first density is less than the second density.

13. The method according to claim 12, wherein, The core layer is made of the same material as the shell layer.

14. The method according to claim 13, wherein, The material is parylene.

15. The method according to claim 12, wherein, The core layer is made of a first material, the shell layer is made of a second material, and the first material is different from the second material.

16. The method of claim 12, further comprising applying the core layer using vapor deposition at a first deposition rate, and applying the shell layer using vapor deposition at a second deposition rate, wherein, The first deposition rate is greater than the second deposition rate.

17. The method according to claim 12, wherein, The lead has a first resonant frequency, and the lead surrounded by the core layer has a second resonant frequency, wherein the first resonant frequency is less than the second resonant frequency.

18. The method according to claim 12, wherein, The core layer has a first thickness, the shell layer has a second thickness, and the first thickness is greater than the second thickness.

19. The method according to claim 18, wherein, The first thickness is one of the following: (i) at least ten times the second thickness; and at least five times the second thickness.

20. The method according to claim 12, wherein, The lead has a first resonance curve with a first quality factor, the lead assembly has a second resonance curve with a second quality factor, and the first quality factor is greater than the second quality factor.

21. The method according to claim 12, wherein, The first density is at least 10% smaller than the second density.

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