Electrical connector using tunable hot melt adhesive material

Abstract

An electrical connector assembly (10) is described having a printed circuit board (32), a signal wire (20), and an impedance mold (34). The signal conductor transmits a signal at a determined signal speed. The signal conductor (20) has an end portion connected to the printed circuit board (32). The impedance mold cooperates with the printed circuit and the signal conductor. The impedance molding (34) is formed from a tunable hot melt adhesive composition. The dielectric constant of the tunable hot melt adhesive composition is reduced to be compatible with a desired signal performance characteristic of a signal transmitted through the signal wire (20) to the printed circuit board (32).

Description

Technical Field

[0001] The present invention relates to a dielectrically modified tunable hot melt adhesive material that enables better matching between electrical components. In particular, the present invention relates to a connector that includes a hot melt adhesive material having a tunable hot melt adhesive compound that is tuned to have a lower dielectric constant. Background Art

[0002] With the recent rapid increase in the speed and amount of data transmission, there is a general need to reduce the size and weight of electronic devices as well as increase their speed. For such devices, it is beneficial to have an electrical insulating material with a target dielectric constant that can adapt to high-speed connector designs. However, current compositions for interconnecting different electrical components currently do not provide a target or adjustable dielectric constant to better match the dielectric contacts of the components. Therefore, there is a need for a simple hot melt adhesive that can be adjusted to a desired dielectric constant to achieve better impedance matching between electrical components. Summary of the invention

[0003] According to the present invention, an electrical connector assembly is provided, which has a printed circuit board, a signal conductor and an impedance molding. The signal conductor transmits a signal at a determined signal speed. The signal conductor has an end connected to the printed circuit board. The impedance molding cooperates with the printed circuit and the signal conductor. The impedance molding is formed by an adjustable hot melt adhesive composition. The dielectric constant of the adjustable hot melt adhesive composition is adjusted to have a lower dielectric constant than the dielectric of the original substrate to be compatible with the desired signal performance characteristics of the signal transmitted to the printed circuit board through the signal conductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 is a perspective view of an illustrative electrical connector having insulated conductors electrically connected to a printed circuit board using a hot melt material that can be adjusted to a desired dielectric constant.

[0005] Figure 2 yes Figure 1 Exploded diagram of .

[0006] Figure 3 yes Figure 1 A partial top view of a connector with the cover removed to show the internal components of the connector.

[0007] Figure 4 yes Figure 3 A side view of the internal components of the connector shown in FIG.

[0008] Figure 5 yes Figure 3 An enlarged view of the area in FIG. 1 shows the adjustable hot melt material located on the interconnect between one of the conductors and the printed circuit board.

[0009] Figure 6 It is similar to the adjustable heat metal material before positioning on the wire and printed circuit board Figure 5 A magnified view of .

[0010] Figure 7 yes Figure 6 Side view of.

[0011] Figure 8 is similar to Figure 6 A magnified view of the circuit with the ground rake removed.

[0012] Fig. 9 yes Figure 8 Side view of. DETAILED DESCRIPTION

[0013] The description of the illustrative embodiments according to the principles of the present invention is intended to be read in conjunction with the accompanying drawings, which should be considered part of the entire written description. In the description of the embodiments of the present invention disclosed herein, any reference to direction or orientation is intended only for convenience of description and is not intended to limit the scope of the invention in any way. Relative terms such as "lower", "upper", "horizontal", "vertical", "above", "below", "upward", "downward", "top" and "bottom" and their derivatives (e.g., "horizontally", "downwardly", "upwardly", etc.) should be interpreted as referring to the orientation as described at the time or the orientation shown in the drawings discussed. These relative terms are only for convenience of description and do not require the device to be constructed or operated in a specific orientation unless explicitly stated. Terms such as "attach", "fix", "connect", "couple", "interconnect" and the like refer to such relationships in which structures are fixed or attached to each other directly or indirectly through intermediate structures, as well as removable or rigid attachments or relationships, unless otherwise explicitly stated.

[0014] Moreover, the features and advantages of the present invention are explained by reference to the preferred embodiments. Therefore, the present invention expressly should not be limited to the embodiments showing some possible non-limiting combinations of features that may exist alone or in other combinations of features, the scope of the present invention being defined by the appended claims.

[0015] like Figure 1 and Figure 2 As shown, the illustrative embodiment of the electrical connector assembly 10 includes a first housing shell 12 and a second housing shell 14. The housing shells 12, 14 are die-cast from materials having desired mechanical and electrical properties. In other embodiments, the housing shells 12, 14 can be molded. The housing shells 12, 14 fit together to enclose the internal components of the connector assembly 10.

[0016] A pull tab 16 extends from the rear of the housing shells 12, 14. The pull tab 16 is molded from rubber or other material having the desired properties. The pull tab 16 has a cover mounting leg 18 that cooperates with one or more of the housing shells 12, 14 to hold the pull tab 16 engaged with the housing shells 12, 14 and the connector assembly 10.

[0017] The ends of the wires 20 are disposed between the housing shells 12, 14 in the connector assembly 10. The wires extend through the rear surface 22 of the connector assembly 10. A wire positioning housing 24 is disposed at the rear surface 22 of the connector assembly 10 to properly position and secure the wires 20 in the connector assembly 10. A strain relief member 26 is also positioned near the rear surface 22 to prevent stress applied to the wires 20 from being transferred into the connector assembly 10. A strain relief securing member 28 facilitates the positioning and operation of the strain relief member 26.

[0018] like Figures 2 to 5 As shown, the connector assembly 10 has an inner assembly or paddle portion 30 to which the wires 20 are electrically connected. The inner assembly 30 includes a double-sided printed circuit board 32, an impedance molding 34, a retaining molding 36, and a strain relief molding 38.

[0019] The circuit board 32 has a signal receiving pad 40, a ground plane 42, a ground rake receiving through hole 44 ( Figure 8 ) and vias 46. The circuit board 32 is constructed in an industry-known manner having a signal layer and a ground layer.

[0020] The fixing mold 36 is made of a basic hot melt composition or other type of material, which is molded on the end of the wire 20 to hold the wire 20 in place. The fixing mold 36 encapsulates a portion of the circuit board 32, such as Figure 4 As shown, to ensure that the wire 20 remains in the proper position on the circuit board 32.

[0021] In the illustrative embodiment shown, the strain relief molding 38 is positioned adjacent to the fixed molding 36 and molded over the end of the wire 20. The strain relief molding 38 is molded from plastic or other material having the desired strength characteristics. Stabilizing protrusions 48 extend from the surface of the strain relief molding 38. The stabilizing protrusions 48 cooperate with one or more of the housing shells 12, 14 to secure and hold the strain relief molding 38 and the internal component 30 in place in the connector assembly 10.

[0022] The conductors 20 have exposed ends 50 that are mounted to the signal receiving pads 40 of the circuit board 32. In the exemplary embodiment shown, each conductor 20 has a differential pair of signal conductors mounted to the signal receiving pads 40, such as Figure 8 and Fig. 9The end portion 50 has a bend 52 that allows the end portion 50 to be mounted in a different plane that is displaced from the longitudinal axis of the wire 20. The end portion 50 can be mounted using solder or other known mounting methods.

[0023] With the end portion 50 properly mounted to the signal receiving pad 40 of the circuit board 32, the grounding member or rake 54 is positioned over the portion of the insulated wire 20 and the bent portion 52 of the end portion 50 of the wire 20. The grounding member or rake 54 is mounted and secured to the ground rake receiving through hole 44 by means of solder or other known mounting methods.

[0024] In the exemplary embodiment shown, the impedance molding 34 is located adjacent to the fixed molding 36. With the grounding member or rake 54 properly installed, the impedance molding 34 is molded over and flows between the grounding rake 54 and the curved portion 52 of the end 50 of the conductor 20. The impedance molding 34 encapsulates the grounding rake 54 and the curved portion 52 of the end 50 of the conductor 20.

[0025] The impedance molding 34 is made of a tunable hot melt adhesive composition that can better match the electrical characteristics between the conductors 20 and the printed circuit board 32. The electrical characteristics include, but are not limited to, the necessary signal performance characteristics, including but not limited to impedance, propagation delay, and crosstalk targets transmitted on and near the differential pairs of signal conductors mounted to the signal receiving pads 40.

[0026] Adjustable hot melt adhesive composition provides a kind of hot melt adhesive composition, and its performance can be changed to realize desired result.In this particular case, adjustable hot melt adhesive composition is adjusted to have lower dielectric constant than the original dielectric constant of hot melt adhesive.Adjustable hot melt adhesive composition can be formed by thermoplastic or thermosetting polymer.Adjustable hot melt adhesive composition should have suitable rheological behavior, wherein can control adhesive flow for connector application, still keep required electrical property and do not have material degradation simultaneously.In one embodiment, adjustable hot melt adhesive can be processed in the temperature range of about 190 ℃ to about 210 ℃.In another embodiment, adjustable hot melt can be processed at the temperature lower than 230 ℃.

[0027] Preferably, using the present invention, the dielectric constant of the tunable hot melt adhesive composition can be changed or adjusted from its neat composition to obtain a desired dielectric constant in the final composition. In one embodiment, the dielectric constant of the tunable hot melt adhesive is reduced from its original dielectric constant.

[0028] In another embodiment, the composition of the tunable hot melt adhesive composition is adjusted to achieve a lower dielectric constant in the range of about 1.6 to about 2.5. The composition comprises a polymer and a filler, and possibly other additives.

[0029] The polymer of the adjustable hot melt adhesive composition can be a thermoplastic polymer or a thermosetting polymer. The polymer used in the adjustable hot melt adhesive composition depends on the end-use application of the adjustable hot melt adhesive composition. The example of suitable thermoplastic polymers includes polyamides, polyolefins, polyurethanes and ethylene vinyl acetate.

[0030] Other examples of thermoplastic polymers that can be used in the tunable hot melt adhesive composition include polyesters, poly(meth)acrylates, polycarbonates, polyvinyl alcohols, polynitriles, polyacetals, polyimides, polyaryl ketones, polyether ketones, polyhydroxyalkanoates, polycaprolactones, polysulfones, polyphenylene oxides, polyphenylene sulfides, polyacetates, liquid crystal polymers, fluoropolymers, ionomer polymers, thermoplastic elastomers, copolymers of any one of them, and combinations of any two or more of them.

[0031] Alternatively, the tunable hot melt adhesive composition can be formed from a thermosetting polymer, as long as the desired viscosity, dielectric constant and dissipation factor of the composition are maintained. Examples of suitable thermosetting polymers to be used in the tunable hot melt adhesive composition include, but are not limited to, epoxies, acrylates, cyanoacrylates and reactive polyurethanes.

[0032] Except polymer, adjustable hot-melt adhesive composition also comprises filler.The filler that can be used for adjustable hot-melt adhesive composition includes but is not limited to: thermoplastic hollow sphere and hollow glass sphere or its combination.Should select the size of filler so that filler can be incorporated into polymer to keep required viscosity, dielectric constant and dissipation factor of adjustable hot-melt adhesive composition.Filler is about 0.5% to about 35% of adjustable hot-melt adhesive composition by weight.Filler causes space in hot-melt adhesive composition.Alternatively, chemical foaming, aerogel, Mucell technology can be used to produce identical effect.

[0033] Thermoplastic hollow spheres typically comprise a thermoplastic shell encapsulating a gas. These thermoplastic hollow spheres may be pre-expanded or unexpanded prior to use. When heated, the internal pressure of the encapsulated gas causes the outer thermoplastic shell to increase and expand. Preferably, unexpanded thermoplastic hollow spheres are used. In one embodiment, the thermoplastic hollow spheres have a density of less than 0.014 g / ml and a particle size in the range of about 20 to about 40 microns. In one embodiment in which only thermoplastic hollow spheres are used in the adjustable hot melt adhesive composition, the thermoplastic hollow spheres account for about 0.5% to about 3.5% of the composition by weight. Examples of commercially available thermoplastic hollow spheres that can be used in the present invention are available from Nouryon Chemical Holding BV Microspheres.

[0034] Alternatively, hollow glass spheres can be used as fillers to reduce the dielectric constant (Dk) of the tunable hot melt adhesive composition. Hollow glass spheres typically include a soda-lime borosilicate shell that encapsulates air. Preferably, these hollow glass spheres have a density ranging from about 0.15 to about 0.4 g / ml and a particle size ranging from about 30 to about 60 microns. In one embodiment, the hollow glass cubes contain about 10% to about 35% of the tunable hot melt adhesive composition by weight. Examples of commercially available hollow glass spheres that can be used in the composition are Glass bulbs, available from Minnesota Mining and Manufacturing Company, St. Paul, Minnesota.

[0035] Adjustable hot-melt adhesive composition can comprise other additive, and condition is to keep required viscosity, dielectric constant and dissipation factor.The example of conventional additive used comprises pigment, dyestuff, voiding agent, antistatic agent, foaming agent, plasticizer, free radical scavenger, antiblocking agent, dustproof agent, antifouling agent, surfactant, smooth auxiliary agent, fluorescent whitening agent, plasticizer, viscosity modifier, gloss improver, dispersion stabilizer, UV stabilizer, UV absorber, antioxidant, lubricant, heat stabilizer, hydrolysis stabilizer, crosslinking activator, layered silicate, radiation sunscreen agent such as barium sulfate, tungsten metal, non-oxide bismuth salt, filler, coloring agent, reinforcing agent, adhesion medium, impact strength modifier, biocide and any combination thereof.Such additive can comprise with conventional amount.Preferably, these other additives are usually in the scope of about 0.5% to about 10% of the composition of adjustable hot-melt adhesive by weight.These additives can be mixed in the adjustable hot-melt adhesive composition in any conventional required mode, to realize the desired characteristic of hot-melt adhesive.

[0036] When thermoplastic hollow spheres are used in the composition, the density of the adjustable hot melt adhesive is about 0.32 to about 0.73 g / mL. When glass spheres are used in the composition, the density of the adjustable hot melt adhesive is about 0.44 to about 0.87 g / mL. The pure polymer used in the adjustable hot melt adhesive has a density of about 0.98 g / mL.

[0037] The flow behavior of the adjustable hot melt adhesive composition was evaluated using oscillatory rheology, and the complex viscosity values ​​were used to compare the adjustable hot melt adhesive composition formulations with the pure polymers used in such compositions. The pure polymer viscosity was about 4.5 Pa.s. When the adjustable hot melt adhesive composition was formed from a polymer and thermoplastic hollow spheres, the complex viscosity was in the range of about 13 Pa.s to 200 Pa.s. When the adjustable hot melt adhesive was formed from glass spheres, the complex viscosity was in the range of about 20 Pa.s to 8×105 Pa.s.

[0038] On the other hand, the present invention relates to the preparation of adjustable hot melt adhesive composition.The method comprises providing polymer, providing at least one filler and optional additive.Use any ordinary method polymer, filler and optional additive are mixed together in granular form to mix materials together.Mixing equipment can be any suitable equipment of mixed concentrated solid in this area.The example of this type of suitable equipment comprises high speed Henschel mixer, ribbon mixer, shaker, forcing machine etc.Filler is configured to provide the polymer composition with suitable physical property such as high heat resistance and high mechanical strength.

[0039] Prior to application, the tunable hot melt adhesive composition is heated and applied in a molten state to form the impedance molding 34. The viscosity and particle size of the tunable hot melt adhesive composition are optimized to provide the desired electrical properties as previously described, and to provide appropriate flow characteristics to allow the tunable hot melt adhesive composition to properly fill all gaps between the ground rake 52, the end 50 of the wire 20 (including the bend 52), the signal receiving pad 40 of the circuit board 32, and the ground plane 42 of the circuit board 32.

[0040] The temperature and force with which the adjustable hot melt adhesive composition is applied to the wire 20 and printed circuit board 32 must also be controlled or adjusted based on the characteristics of the wire 20 and printed circuit board 32. The application of the adjustable hot melt adhesive composition must be performed at a temperature below the melting point of the components of the wire 20. The force or pressure with which the adjustable hot melt adhesive composition is applied must be below a force or pressure that would cause deformation or compression of the wire 20. Any such deformation of the bent portion 52 of the end portion 50 of the wire 20 may result in undesirable changes in the signal transmission of the wire 20.

[0041] The present invention relates to an adjustable hot melt adhesive composition in the form of an impedance molding 34 that can be adjusted or tuned to have a lower dielectric constant compatible with necessary signal performance characteristics, including but not limited to impedance, propagation delay, and crosstalk targets transmitted on and near the connection between the end 50 of the conductor 20 and the circuit board 32. The adjustable hot melt adhesive composition in the form of the impedance molding 34 is tuned to be between the impedance of the end 50 of the conductor 20 and the impedance of the circuit board 32, thereby bridging the impedance difference between the components to allow current to flow better and more evenly from the end 50 of the conductor 20 through the impedance molding 34 and to the printed circuit board 32.

[0042] By varying the composition of the adjustable hot melt adhesive composition in the form of the impedance molding member 34, the dielectric properties of the impedance molding member 34 and the connector assembly 10 can be adjusted to minimize the propagation delay of the signal when the signal is transmitted through the signal conductors to the circuit board, thereby minimizing interference with the signal transmitted based on the signal speed, which in turn optimizes signal transmission.

Claims

1. An electrical connector assembly (10), include: Printed circuit board (32); A signal conductor (20) for transmitting a signal at a determined signal speed, the signal conductor having an end connected to the printed circuit board (32); an impedance molding (34) cooperating with the printed circuit (32) and the signal conductor (20), the impedance molding (34) being formed of an adjustable hot melt adhesive composition having an initial dielectric constant; The dielectric constant of the adjustable hot melt adhesive composition is adjusted to have a lower dielectric constant than an initial dielectric constant of the composition so as to be compatible with desired signal performance characteristics of a signal transmitted to the printed circuit board (32) via the signal conductor (20).

2. The electrical connector assembly (10) according to claim 1, in, A grounding member (54) is positioned on a portion of the insulated conductor (20).

3. The electrical connector assembly (10) according to claim 2, in, The grounding member (54) is encapsulated by the impedance molding (34).

4. The electrical connector assembly (10) according to claim 3, in, The grounding member (54) is positioned on the bent portion (52) of the end portion (50) of the wire (20).

5. The electrical connector assembly (10) according to claim 4, in, The grounding member (54) is mounted and fixed on the circuit board (32).

6. The electrical connector assembly (10) according to claim 1, in, The tunable hot melt adhesive composition can be formed from thermoplastic or thermosetting polymers.

7. The electrical connector assembly (10) according to claim 1, in, The tunable hot melt adhesive composition has a density of less than 0.87 g / mL.

8. The electrical connector assembly (10) according to claim 1, in, The tunable hot melt adhesive composition is adjusted to obtain a dielectric constant of the material of about 2.

5.

9. The electrical connector assembly (10) according to claim 1, in, The tunable hot melt adhesive composition is adjusted to obtain a dielectric constant of the material of about 1.

6.

10. The electrical connector assembly (10) according to claim 1, in, The tunable hot melt adhesive composition includes a polymer.

11. The electrical connector assembly (10) according to claim 10, in, The tunable hot melt adhesive composition is a thermoplastic polymer or a thermosetting polymer.

12. The electrical connector assembly (10) according to claim 11, in, The thermoplastic polymer is selected from the group consisting of polyamides, polyolefins, polyurethanes and ethylene vinyl acetate.

13. The electrical connector assembly (10) according to claim 11, in, The thermosetting polymer is selected from the group consisting of epoxies, cyanoacrylates and reactive polyurethanes.

14. The electrical connector assembly (10) according to claim 1, in, The tunable hot melt adhesive composition comprises at least one filler.

15. The electrical connector assembly (10) according to claim 14, in, The at least one filler is selected from the group consisting of thermoplastic hollow spheres and hollow glass spheres.

16. The electrical connector assembly (10) according to claim 14, in, The size of the at least one filler is selected to maintain a desired viscosity, dielectric constant, and dissipation factor of the tunable hot melt adhesive composition.

17. The electrical connector assembly (10) according to claim 14, in, The at least one filler comprises from about 0.5% to about 35% by weight of the tunable hot melt adhesive composition.

18. The electrical connector assembly (10) according to claim 1, in, The tunable hot melt adhesive composition includes a polymer, a filler and an additive.

19. The electrical connector assembly (10) according to claim 18, in, Additional additives range from about 0.5% to about 10% by weight of the tunable hot melt adhesive composition.

20. The electrical connector assembly (10) according to claim 1, in, The tunable hot melt adhesive composition includes a polymer, a filler, and an additive, and has a density in a range of about 0.32 g / mL to about 0.73 g / mL.

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