Method of encapsulating hard disc drive and other electrical components

Abstract

A method for injection molding a layer of phase change material around a surface of a plurality of identical motor components or hard disc drive components which includes providing a plurality of motor components or hard disc drive components; placing a motor component or hard disc drive component in a mold cavity of an injection molding machine having a controllable fill rate and a controllable injection pressure; closing said mold cavity; injecting a molten phase change material into said mold cavity at a fill rate and injection pressure; monitoring pressure in the mold cavity; controlling the fill rate of molten phase change material to obtain said motor component or hard disc drive component with the phase change material thereon, having a reproducible resonance spectrum; and repeating the above steps to produce a plurality of motor components or hard disc drive components each having a substantially uniform resonance spectrum.

1 . A method for injection molding a layer of phase change material around a hard disc drive voice coil motor component comprising: 
 a) providing a voice coil motor winding;    b) placing said winding in a mold cavity of an injection molding machine having a controllable fill rate and a controllable injection pressure;    c) closing said mold cavity;    d) injecting a molten phase change material into said mold cavity;    e) monitoring pressure of the phase change material at at least one point in the mold during the injection of the molten phase change material; and    f) monitoring and controlling one or more of the fill rate and injection pressure of said molten phase change material to duplicate a predetermined time-pressure curve for each monitoring point in the mold.    
   
   
       2 - 17 . (canceled)  
   
   
       18 . The method of  claim 1  wherein a plurality of identical hard disc drive components comprising at least one hundred voice coil motor winding components are molded with phase change material thereon, said at least one hundred components having a median first order frequency and wherein each of said at least one hundred hard disc drive components with a phase change material thereon has a first order frequency that is within about three hundred Hertz of said median first order frequency.  
   
   
       19 . The method of  claim 18  wherein each of said at least one hundred hard disc drive components with a phase change material thereon has a first order frequency that is within about one hundred Hertz of said median first order frequency.  
   
   
       20 . The method of  claim 18  wherein each of said at least one hundred hard disc drive components with a phase change material thereon has a first order frequency that is within about thirty Hertz of said median first order frequency.  
   
   
       21 . The method of  claim 1  wherein a plurality of identical hard disc drive components comprising voice coil motor windings are molded with phase change material and the resonance spectra of said plurality of hard disc drive components with phase change material thereon have a standard deviation of first order resonance frequency that is at least about twenty five percent less than the standard deviation of the first order resonance frequency for the same number of the same components over-molded with an injection molding process wherein only the injection pressure and either the injection time or stroke of an extrusion screw are controlled.  
   
   
       22 . The method of  claim 1  wherein a plurality of identical hard disc drive components comprising voice coil motor windings are molded with phase change material and the resonance spectra of said plurality of hard disc drive components with phase change material thereon have a standard deviation of first order resonance frequency that is at least about fifty percent less than the standard deviation of the first order resonance frequency for the same number of the same components over-molded with an injection molding process wherein only the injection pressure and either the injection time or stroke of an extrusion screw are controlled.  
   
   
       23 - 33 . (canceled)  
   
   
       34 . A method of manufacturing hard disc drives having a reproducible resonance spectrum comprising: 
 a) providing a plurality of identical hard disc drive component sets, wherein each of said sets consists of components that are used in a single hard disc drive;    b) placing and positioning one of said plurality of hard disc drive component sets in a mold cavity of an injection molding machine;    c) closing said mold cavity;    d) monitoring the pressure inside the mold;    e) injecting a molten phase change material into said mold cavity to a pre-determined pressure gradient; and    f) repeating steps b)-e) to produce a plurality of hard disc drives each having a substantially uniform resonance spectrum.    
   
   
       35 - 38 . (canceled)  
   
   
       39 . The method of  claim 34  wherein said set of hard disc drive components comprises a stator and a base plate.  
   
   
       40 . The method of  claim 34  wherein said plurality of said hard disc drive component sets comprise at least one hundred component sets with phase change material thereon, said at least one hundred component sets having a median first order frequency and wherein each of said at least one hundred hard disc drive component sets with a phase change material thereon has a first order frequency that is within about three hundred Hertz of said median first order frequency.  
   
   
       41 . The method of  claim 40  wherein each of said at least one hundred hard disc drive component sets with a phase change material thereon has a first order frequency that is within about one hundred Hertz of said median first order frequency.  
   
   
       42 . The method of  claim 40  wherein each of said at least one hundred hard disc drive component sets with a phase change material thereon has a first order frequency that is within about thirty Hertz of said median first order frequency.  
   
   
       43 . The method of  claim 34  wherein the resonance spectra of said plurality of hard disc drive component sets with phase change material thereon have a standard deviation of first order resonance frequency that is at least about twenty five percent less than the standard deviation of first order resonance frequency for the same number of the same component sets over-molded with an injection molding process wherein only the injection pressure and either the injection time or stroke of an extrusion screw are controlled.  
   
   
       44 . The method of  claim 34  wherein the resonance spectra of said plurality of hard disc drive component sets with phase change material thereon have a standard deviation of first order resonance frequency that is at least about fifty percent less than the standard deviation of first order resonance frequency for the same number of the same component sets over-molded with an injection molding process wherein only the injection pressure and either the injection time or stroke of an extrusion screw are controlled.  
   
   
       45 . (canceled)  
   
   
       46 . A method of injection molding a layer of phase change material around a surface of a motor component comprising: 
 a) providing a motor component;    b) placing said motor component in a mold cavity of an injection molding machine having a controllable fill rate and a controllable injection pressure;    c) closing said mold cavity;    d) injecting a molten phase change material into said mold cavity;    e) monitoring pressures of the phase change material at at least one point in the mold cavity during the injection of the molten phase chance material; and    f) using the monitored pressure and a controller to control the fill of said molten phase change material during injection in a manner that attempts to duplicate a predetermined time-pressure curve for each said point in the mold, to thereby obtain said motor component with the phase change material thereon.    
   
   
       47 - 52 . (canceled)  
   
   
       53 . The method of  claim 46  wherein a plurality of identical motor components comprising at least one hundred components are molded with phase chance material thereon, said at least one hundred components having a median first order frequency and wherein each of said at least one hundred motor components with a phase change material thereon has a first order frequency that is within about three hundred Hertz of said median first order frequency.  
   
   
       54 . The method of  claim 53  wherein each of said at least one hundred motor components with a phase change material thereon has a first order frequency that is within about one hundred Hertz of said median first order frequency.  
   
   
       55 . The method of  claim 53  wherein each of said at least one hundred hard disc drive components with a phase change material thereon has a first order frequency that is within about thirty Hertz of said median first order frequency.  
   
   
       56 . The method of  claim 46  wherein a plurality of identical motor components are molded with phase change material and the resonance spectra of said plurality of motor components with phase change material thereon have a standard deviation of first order resonance frequency that is at least about twenty five percent less than the standard deviation of first order resonance frequency for the same number of the same components over-molded with an injection molding process wherein only the injection pressure and either the injection time or stroke of an extrusion screw are controlled.  
   
   
       57 . The method of  claim 46  wherein a plurality of identical motor component sets are molded with phase change material and the resonance spectra of said plurality of motor component sets with phase change material thereon have a standard deviation of first order resonance frequency that is at least about fifty percent less than the standard deviation of first order resonance frequency for the same number of the same components over-molded with an injection molding process wherein only the injection pressure and either the injection time or stroke of an extrusion screw are controlled.  
   
   
       58 - 75 . (canceled)  
   
   
       76 . A method of manufacturing motors having a reproducible resonance spectrum comprising: 
 a) providing a plurality of identical motor component sets, wherein each of said sets consists of components that are used in a single motor;    b) placing and positioning one of said plurality of motor component sets in a mold cavity of an injection molding machine;    c) closing said mold cavity;    d) monitoring the pressure inside the mold;    e) injecting a molten phase change material into said mold cavity to a pre-determined cavity pressure gradient; and    f) repeating steps b)-e) to produce a plurality of motors each having a substantially uniform resonance spectrum.