PATENT DOCUMENT

Publication Number: US-9682500-B2
Application Number: US-201314108148-A
Country: US
Kind Code: B2

Title: Insert molded parts and methods for forming the same

Abstract:
The embodiments described herein relate to insert molding methods. The methods involve partially or fully encasing an insert within a thermoplastic material, forming a composite part that includes the insert and the molded thermoplastic material. Methods described provide a number of improvements over traditional insert molding techniques. In specific embodiments, a two-shot molding process is used whereby a first shot is formed on a first portion of the insert and a second shot is formed on a second portion of the insert. The insert molding processes can be performed using a single mold during the first and second injection molding processes.

Claims:
What is claimed is: 
     
       1. A method for forming a composite part having an insert and a molded piece, the method comprising:
 securing the insert within a mold using a support mold, the insert having a first surface area and a second surface area, wherein the support mold covers the second surface area; 
 forming a first portion of the molded piece on the first surface area by injecting a first resinous material into the mold and onto the first surface area; 
 removing the support mold from the insert, thereby exposing the second surface area of the insert via a recess within the first portion; and 
 forming a second portion of the molded piece by injecting a second resinous material through a gate portion of the mold into the recess and onto the second surface area, wherein the gate portion forms an indentation within molded piece. 
 
     
     
       2. The method as recited in  claim 1 , wherein the first portion of the molded piece and the second portion of the molded piece are composed of the same thermoplastic material. 
     
     
       3. The method as recited in  claim 1 , wherein forming the first and second portions of the molded piece comprises partially encasing the insert within the molded piece. 
     
     
       4. The method as recited in  claim 1 , wherein forming the first and second portions of the molded piece comprises substantially fully encasing the insert within the molded piece. 
     
     
       5. The method as recited in  claim 1 , wherein injecting the first resinous material comprises injecting the first resinous material through a first runner system and injecting the second resinous material comprises injecting the second resinous material through a second runner system, wherein the first runner system is different than the second runner system. 
     
     
       6. The method as recited in  claim 1 , wherein the mold includes more than one gate portion such that more than one indentation is formed within the molded piece. 
     
     
       7. The method as recited in  claim 1 , wherein forming the first portion and the second portion involves forming a watertight barrier between at least a portion of the insert and an outer environment. 
     
     
       8. A composite part, comprising:
 an insert having a first surface area and a second surface area; and 
 a molded piece formed using an injection molding process, the molded piece comprising:
 a first portion disposed on the first surface area of the insert, the first portion including a recess that provides access to the second surface area of the insert, 
 a second portion disposed on the second surface area of the insert by way of the recess, and 
 an indentation disposed within the first portion, the indentation formed during the injection molding process. 
 
 
     
     
       9. The composite part as recited in  claim 8 , wherein the first portion and the second portion comprise the same thermoplastic material. 
     
     
       10. The composite part as recited in  claim 8 , wherein the insert is partially encased within the molded piece. 
     
     
       11. The composite part as recited in  claim 8 , wherein the insert is substantially fully encased within the molded piece. 
     
     
       12. The composite part as recited in  claim 8 , wherein the composite part is part of an electronic device. 
     
     
       13. The composite part as recited in  claim 8 , wherein the insert is an electronic component. 
     
     
       14. The composite part as recited in  claim 13 , wherein the electronic component is a printed circuit board. 
     
     
       15. The composite part as recited in  claim 8 , wherein the first portion and the second portion create a watertight barrier between at least a portion of the insert and an outer environment. 
     
     
       16. The composite part as recited in  claim 8 , wherein the composite part includes two indentations formed during the injection molding process. 
     
     
       17. An electronic device, comprising:
 a printed circuit board having a first surface area and a second surface area; and 
 a molded piece at least partially encasing the printed circuit board therein, the molded piece formed using an injection molding process, the molded piece comprising:
 a first portion disposed on the first surface area, the first portion including a recess that provides access to the second surface area of the printed circuit board, 
 a second portion disposed on the second surface area via the recess, and 
 an indentation disposed within the molded piece, the indentation formed during the injection molding process. 
 
 
     
     
       18. The electronic device as recited in  claim 17 , wherein the first portion and the second portion comprise the same material. 
     
     
       19. The electronic device as recited in  claim 17 , wherein the molded piece creates a watertight barrier between at least a portion of the printed circuit board and an outer environment. 
     
     
       20. The electronic device as recited in  claim 17 , wherein the indentation is proximate to the second portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 61/884,890, filed Sep. 30, 2013 and entitled “INSERT MOLDING METHODS,” which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     This disclosure relates generally to injection molded parts and injection molding methods. In particular, tooling concepts for improving insert molding methods are disclosed. 
     BACKGROUND 
     Injection molding generally involves melting thermoplastic or thermosetting material and injecting the melted material into a mold cavity. The volume of material that is used to fill the mold cavity is referred to as a shot. The thermoplastic material is then allowed to cool and take on a shape corresponding to the mold cavity. One type of injection molding, often referred to as insert molding or overmolding, involves injection molding material around a separate part, referred to as an insert piece. The resultant part is a composite part that includes the insert piece and the molded material. Insert molding generally involves a two-shot or multi-shot technique where two or more injection molding processes are performed on a single part. A two-shot method involves injection molding one part, transferring the part to a second mold as an insert, and molding the second component against the first. Multi-shot methods involve multiple injection steps. In some cases, two-shot and multi-shot methods can be processed on specialized injection molding machines that have two or more injection units. These two-shot and multi-shot molding machines are expensive and highly specialized for producing particular parts. What are needed are simple and inexpensive alternatives to traditional insert molding methods. 
     SUMMARY 
     According to one embodiment, a method for forming a composite part having an insert and a molded portion is described. The method includes securing the insert within a mold using at least one support mold. The insert has a first surface in contact with the support mold and an exposed second surface. The method also includes forming a first part of the molded portion by injecting a first resinous material into the mold. During the injecting, the first resinous material covers the second surface of the insert. The method additionally includes removing the support mold from the first surface of the insert exposing the first surface of the insert and forming a recess within the first part of the molded portion. The method further includes forming a second part of the molded portion by injecting a second resinous material into the recess and over the first surface of the insert such that the first surface and second surface of the insert are encased within the molded portion. 
     According to another embodiment, a composite part is described. The composite part includes an insert having a first surface and a second surface. The composite part also includes a molded piece formed using an injection molding process. The molded piece includes a first molded portion molded onto the second surface of the insert. The molded piece also includes a second molded portion molded onto the first surface of the insert and onto at least a section of the first molded portion. The molded piece also includes an indentation disposed within the first molded portion. The indentation is formed during the injection molding process. 
     According to a further embodiment, an electronic device is described. The electronic device includes a printed circuit board having a first surface and a second surface. The electronic device also includes a molded piece at least partially encasing the printed circuit board therein. The molded piece is formed using a molding process. The molded piece includes a first molded portion disposed on the second surface of the printed circuit board. The molded piece also includes a second molded portion disposed on the first surface of the printed circuit board and disposed on at least a section of the first molded portion. The molded piece further includes an indentation disposed within the first molded portion. The indentation is formed during the molding process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The described embodiments and the advantages thereof may best be understood by reference to the following description taken in conjunction with the accompanying drawings. These drawings in no way limit any changes in form and detail that may be made to the described embodiments by one skilled in the art without departing from the spirit and scope of the described embodiments. 
         FIGS. 1A and 1B  show perspective views of a part at different stages of manufacture using a two-shot insert molding method in accordance with described embodiments. 
         FIGS. 2-10  show cross-section views of an injection molding system during different stages of manufacture of forming the part shown in  FIGS. 1A and 1B . 
         FIGS. 11-14  show schematic views of an injection molding system during different stages of manufacture of forming another part. 
         FIG. 15  shows a flowchart indicating an insert molding process in accordance with described embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Representative applications of methods according to the present application are described in this section. These examples are being provided solely to add context and aid in the understanding of the described embodiments. It will thus be apparent to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the described embodiments. Other applications are possible, such that the following examples should not be taken as limiting. 
     The present application describes various methods and apparatuses used in injection molding processes. In particular, improved insert molding techniques that are simple and inexpensive alternatives to traditional insert molding techniques are described. In specific embodiments, a two-shot molding technique is performed using a single mold cavity, saving machine costs and production time during manufacture. Methods described are well suited in the manufacture of molded parts of electronic devices including desktop computers, laptop computers, smart phones, and media players, such as those designed and sold by Apple Inc. headquartered in Cupertino, Calif. 
     Insert molding is a molding process whereby one portion of a part, referred to as an insert, is partially or fully encased within a thermoplastic or resinous material. The insert molded part is a composite part that includes the insert and the molded thermoplastic material. The insert can be made of any suitable material, including metal, glass, ceramic, or a combination of different materials. In some cases, the insert is made of a thermoplastic material similar to thermoplastic material that is molded around the insert. In some cases, the insert is an electronic component, such as printed circuit board (PCB) or a battery. In some applications, encasing electronic components within thermoplastic material can be used to create a watertight barrier between the electronic component and an outer environment. 
     In order to encase exposed surfaces of an insert using injection molding techniques, at least two injection molding steps are required. These methods are referred to as two-shot or multi-shot molding processes. A traditional two-shot process involves holding the insert and securing the insert within a first mold. A first shot of thermoplastic material is then injected into the first mold, encasing a portion of the insert within the first shot of thermoplastic material. The first mold is then opened and the part is removed from the first mold. The part is then held at a location on the first shot portion of the part and secured within a second mold. A second shot of thermoplastic material is then injected into the second mold to complete the composite part. In some cases, the transfer to the second mold involves moving the part to another tool. In other cases, the first and second molds are part of a multi-cavity mold on a specialized two-shot injection tool. The tool is configured to rotate the mold from the first cavity to the second cavity between injections. These two-shot injection molding tools can be very expensive and are often customized to produce specific parts. In addition, transferring the part from a first to a second mold can create opportunity for moisture to form on the surfaces of the part, diminishing the quality of the seal between the first and second shots. 
     Described herein are improved insert molding techniques designed to encase an exposed surface of an insert within a thermoplastic material without the use of multiple molds or cavities.  FIGS. 1A and 1B  show perspective views of part  100  at different stages of manufacture using an insert molding method in accordance with described embodiments.  FIG. 1A  shows part  100  after a first shot injection is performed. Part  100  includes insert  104 , which is encased within first shot  102  (which can be referred to as a first portion). In the embodiment shown, insert  104  is an electronic component, specifically a printed circuit board (PCB). It should be noted that insert  104  is not limited to any particular type of component and that any suitable insert can be used. In some embodiments, the insert is a different type of electronic component, such as a battery. In other embodiments, the insert is a non-electronic component, such as a piece of metal, glass, ceramic, etc. In some embodiments, multiple inserts are used. First shot  102  can be made of any suitable moldable material, such as any suitable thermoplastic materials. 
     As shown at  FIG. 1A , first shot  102  is disposed on a first surface area  114  of insert  104  and includes recess  106 , which provides access to a second surface area  116  of insert  104 . Recess  106  corresponds to a support mold used during the molding process and that will be described below in detail. Note that in traditional two-shot injection molding processes, part  100  would be removed from a first mold and transferred to a second mold for injection of the second shot. This transfer would allow the plastic of first shot  102  to cool making the bond and seal for the second shot less effective. 
       FIG. 1B  shows part  100  after a second shot injection is performed. As shown, second shot  108  (which can be referred to as a second portion) is inserted within recess  106 , with interface  110  defining the junction between first shot  102  and second shot  108 . Thus, second shot  108  is disposed on second surface area  116  of insert  104  by way of recess  106 . Methods described herein make it possible to form second shot  108  within recess  106  without transferring part  100  to a second mold. In addition, the methods described herein can be used to form first shot  102  and second shot  108  out of the same stock of thermoplastic material, thereby allowing first  102  and second  108  shots to match in texture and color. In some embodiments, first  102  and second  108  shots match such that interface  110  is not visible after the part is complete. It should be noted, however, that methods described herein are not limited to first  102  and second  108  shots made of the same material. In some embodiments, first  102  and second  108  shots are made of different materials. First  102  and second  108  shots can have the same or different colors. Dimple  112  is an indentation that corresponds to a gate portion of a runner system used during the second shot injection and will be described below in detail. 
       FIGS. 2-10  show cross-section views of an injection molding system  200  during different stages of manufacture of part  100 . In should be noted that for illustrative purposes,  FIGS. 2-10  are cross-section views that show half of the molding system  200  and part  100 .  FIG. 2  shows molding system  200  with insert  104  placed within mold  202  and ready for injection of a first shot. Note that for illustrative purposes, only a bottom portion of mold  202  is shown and not side portions of mold  202 . Molding system  200  includes runner mold  204 , resin flow director  212 , top gate  210 , support mold  214 , and top frame  213 . Support mold  214  is positioned at a first position on a surface of insert  104  to press down on and secure insert  104  within mold  202  during the first shot injection. Runner mold  204  includes first runner  206  and second runner  208 , which direct the flow of resin during a first shot and second shot, respectively. Resin flow director  212  includes first channel  216  and second channel  218 , which direct the flow of resin during a first shot and second shot, respectively. 
       FIG. 3  shows molding system  200  during a first shot injection. As shown, resin flow director  212  directs resin  320  to flow from top gate  210 , through first channel  216 , through first runner  206 , and into mold  202 , forming first shot  102 . Support mold  214  remains on the surface of and secures insert  104  during the first shot injection. After the first shot injection, first shot  102  is allowed to cool until it is sufficiently firm so as not to deform during a second shot injection. 
       FIG. 4 . shows molding system  200  after first shot  102  is complete and has begun transition to a configuration for a second shot injection. Runner mold  204  is allowed to remain situated on first shot  102  while top gate  210 , flow director  212 , support mold  214 , and top frame  213  are moved up. As shown, sprue  422 , which is the hardened portion of resin left within runner  206  and channel  216 , is separated from first shot  102 . At  FIG. 5 , sprue  422  is removed from molding system  200  and discarded. Sprue  422  can be removed using any suitable method, such as by a robotic mechanism that grabs and removes sprue  422  from system  200 . 
       FIG. 6  shows resin flow director  212  displaced to a second position such that top gate  210  is positioned to inject resin into channel  218  of resin flow director  212 . In molding system  200 , resin flow director  212  is configured to be displaced by sliding action  224 . Sliding action  624  can be executed using any suitable method, including manual movement, electronic or hydraulic activation as part of system  200 , or by aid of a robot. In other embodiments, resin flow director  212  can be designed to move in a different motion, such as by rotation. In some embodiments, sliding action  624  of resin flow director  212  is done simultaneously with removal of sprue  422  (shown in  FIG. 4 ). That is, sprue  422  can be forced or sheared away from resin flow director  212  during sliding  624 , eliminating a separate sprue  422  removal procedure. 
     In addition to sliding action  624  of resin flow director  212 , support mold  214  is moved upward  626  relative to top frame  213  to a second position. Moving support mold  214  upward  626  in the second position will allow recess  106  to form within first shot  102 . The upward  626  movement of support mold  214  can be executed using any suitable method, including manual movement, electronic or hydraulic activation as part of system  200 , or with use of a robot. In some embodiments, resin flow director  212  and support mold  214  are mechanically coupled such that sliding movement  624  and upward movement  626  are simultaneously activated using a single mechanism. 
       FIG. 7  shows molding system  200  configured for a second shot injection. Top gate  210 , flow director  212 , support mold  214 , and top frame  213  are moved back down over first shot  102 . Gate portion  728 , which is a protruding portion of runner mold  204  and allows the second shot injection to travel through second runner  208  to recess  106 , is allowed to descend back into its same position during the first shot injection. As shown, support mold  214  is positioned at a second position, different than the first position during the first shot injection. In the second position, support mold  214  is suspended above recess  106  so that the second shot can be injected into recess  106 . In addition, resin flow director  218  is positioned at its second position to allow resin to flow from top gate  210  through second channel  218  and second runner  208  into recess  106 . 
       FIG. 8  shows molding system  200  during a second shot injection. As shown, resin flow director  212  directs resin  826  to flow from top gate  210 , through second channel  218 , through second runner  208 , and into recess  106 , forming second shot  108 .  FIG. 9  shows molding system  200  after second shot  108  is sufficiently cooled and hardened for removal without deformation. Dimple  112 , corresponding to gate portion  728 , remains within part  100 . Runner mold  204 , top gate  210 , resin flow director  212 , support mold  214 , and top frame  213  are moved up out of mold  202 . As shown, sprue  930 , which is the hardened portion of resin left within runner  208  and channel  218 , is separated from second shot  108 . Part  100  is ready for removal from mold  202  and molding system  200 . At  FIG. 10 , sprue  930  is removed from molding system  200  and discarded. Sprue  930  can be removed using any suitable method, such as by a robotic mechanism that grabs and removes sprue  930  from system  200 . Injection molding system  200  is now ready for injection molding of another part. 
     In another embodiment, the insert can be fully encased within a thermoplastic material.  FIGS. 11-15  show schematic views of an injection molding system  1100  during different stages of manufacture of part  1101 . Injection molding system  1100  is similar to injection molding system  200  described above but with additional features that allow a resinous material to encase all sides of an insert.  FIG. 11  shows molding system  1100  during a first shot injection. Molding system  1100  includes resin flow director  1102 , first support mold  1104 , second support mold  1106 , top gate  1108 , and mold  1110 . A top frame, similar to top frame  213  described above, and a runner mold, similar to runner mold  204  described above, are not shown for simplicity purposes. Resin flow director  1102  is configured to direct the flow of resin from top gate  1108  though either a first runner system  1112  or a second runner system  1114 . First runner system  1112  is configured to allow resin to flow during a first shot injection. Second runner system  1114  is configured to allow resin to flow during a second shot injection. 
     Prior to the first shot injection, insert  1118  is secured within mold  1110  on one side by first support mold  1104  and on another side by second support mold  1106 . In addition, resin flow director  1102  is arranged to direct the flow of resin from top gate  1108  through first runner system  1112 . During a first shot injection, resin  1116  flows from top gate  1108 , through first runner system  1112 , and into mold  1110 , forming first shot  1120  surrounding insert  1118 . As shown, after the first shot injection is complete and first shot  1120  is sufficiently hardened, remaining resin  1116  (sprue) within first runner system  1112  can be removed. 
       FIG. 12  shows molding system  1100  prepared for a second shot injection. First support mold  1104  and second support mold  1106  are moved away from the surface of insert  1118  since first shot  1120  now provides support for insert  1118  within mold  1110 . As shown, removal of first support mold  1104  and second support mold  1106  from insert  1118  creates cavities  1222  and  1224 , respectively. Cavities  1222  and  1224  are voids within first shot  1120  in which the second shot will be formed. In addition, resin flow director  1102  is arranged to direct the flow of resin from top gate  1108  though second runner system  1114 . 
       FIG. 13  shows molding system  1100  during a second shot injection. During the second shot injection, resin flow director  1102  allows resin  1326  to flow from top gate  1108 , through second runner system  1114 , and into cavities  1222  and  1224 , forming top second shot portion  1328  and bottom second shot portion  1330 . After the second shot injection is complete and top second shot portion  1328  and bottom second shot portion  1330  are sufficiently hardened, composite part  1101  is complete and can be removed. In addition, remaining resin  1326  (sprue) within second runner system  1114  can be removed and molding system  1100  is ready for producing another part. 
       FIG. 14  shows completed composite part  1101 . Composite part  1101  includes insert  1118  that is fully encased within a resinous material, which includes first shot  1120 , top second shot portion  1328 , and bottom second shot portion  1330 . In some embodiments, first shot  1120 , top second shot portion  1328 , and bottom second shot portion  1330  are made of the same stock of resin such that an interface between the first and second shot portions is not visible. Dimples  1432  and  1434 , corresponding to gate portions, similar to gate portion  728  describe above with reference to part  200  of  FIGS. 2-10 , can exist on part  1100 . 
     Note that embodiments described above are for illustrative purposes and are not representative of all possible embodiments, as would be apparent to a person of skill in the art. For example, multiple-shot insert molding methods involving more than two shots can be performed. In addition, multiple inserts can be encased within a thermoplastic material using the methods described above. 
       FIG. 15  shows flowchart  1500  indicating an insert molding process to form a composite part in accordance with described embodiments. At  1502 , an insert is secured within a mold using at least one support mold. The support mold can be configured to removably couple to the insert, such as by pressing a surface of the support mold against a surface of the insert. In some embodiments, two support molds are used. At  1504 , a first shot is formed within the mold and around a first surface of the insert. In some embodiments, this is accomplished by injecting a resinous material while in liquid form into the mold. The support mold can secure the insert in place during injection of the resinous material. After the injection process is complete, the resinous material can be allowed to sufficiently cool and harden. 
     At  1506 , the support mold is removed from the first shot, forming a recess within the first shot and exposing a second surface of the insert. In addition, the molding tool or system can be adjusted to prepare for a second shot injection. This can be accomplished, for example, using a resin flow director that directs the flow of resin between a first runner system during the first shot injection and a second runner system during a second shot injection. Thus, prior to the second shot injection, the resin flow director can be adjusted to allow resin to flow through the second runner system. At  1508 , a second shot is formed within the recess formed by the support structure and over the second surface of the insert. In some embodiments, this is accomplished by injecting a resinous material while in liquid form into the recess. After the resinous material is allowed to sufficiently cool and harden, the composite part is complete and can be removed from the mold. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of specific embodiments are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the described embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20131216
Publication Date: 20170620
Grant Date: 20170620
Priority Date: 20130930
Inventors: STANLEY CRAIG M.
Assignee: APPLE INC
CPC Classifications: [{"code": "Y10T428/239", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/1671", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C45/1635", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C45/1671", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T428/23", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/1635", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/23", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2031/3425", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2031/3425", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/14065", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T428/239", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/14065", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29C45/1671", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/239", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/23", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/1635", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29L2031/3425", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 52739963