Chip on board and heat sink attachment methods
First Claim
1. A method for preventing material from adhering to at least a portion of a surface of a semiconductor die, comprising:
- applying a layer of material for masking a portion of said surface of said semiconductor die, said layer including at least one of a gel, an elastomeric material, and a material having filler particles therein;
applying an encapsulant material to a remaining portion of said surface of said semiconductor die;
curing said encapsulant material; and
removing at least a portion of said layer of material from at least a portion of said surface of said semiconductor die.
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Abstract
A process for forming a thermally enhanced Chip On Board semiconductor device with a heat sink is described. In one aspect, a thermally conductive-filled gel elastomer or a silicon elastomeric material or elastomeric material, if the material is to be removed, is applied to the die surface to which the heat sink is to be bonded. During the subsequent glob top application and curing steps, difficult-to-remove glob top material which otherwise may be misapplied to the die surface adheres to the upper surface of the elastomer material. The elastomer material is removed by peeling prior to adhesion bonding of the heat sink to the die. In another aspect, the thermally conductive-filled gel elastomer is applied between a die surface and the inside attachment surface of a cap-style heat sink to eliminate overpressure on the die/substrate interface.
182 Citations
90 Claims
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1. A method for preventing material from adhering to at least a portion of a surface of a semiconductor die, comprising:
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applying a layer of material for masking a portion of said surface of said semiconductor die, said layer including at least one of a gel, an elastomeric material, and a material having filler particles therein;
applying an encapsulant material to a remaining portion of said surface of said semiconductor die;
curing said encapsulant material; and
removing at least a portion of said layer of material from at least a portion of said surface of said semiconductor die. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
providing a heat sink having at least one surface; and
securing said heat sink to said surface of said semiconductor die.
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10. The method of claim 2, wherein said silicon gel material includes a gel elastomer material filled with heat conductive particles whereby heat conductivity is enhanced.
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11. The method of claim 10, wherein said heat conductive particles include metal particles, carbon particles, and diamond-filled thermally conductive material in particle form.
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12. The method of claim 1, wherein said layer of material includes a dam extending a portion of a length of at least one side of said semiconductor die.
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13. The method of claim 12, wherein said dam extends a portion of a length of a plurality of sides of said semiconductor die.
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14. The method of claim 9, wherein said heat sink is resiliently mounted to said surface of said semiconductor die.
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15. A method for preventing at least a portion of a material from adhering to at least a portion of a surface of a chip scale semiconductor package, comprising:
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applying a layer of material as a mask to at least a portion of said surface of said chip scale semiconductor package, said layer including at least one of a gels a material having a filler therein and an elastomeric material;
applying an encapsulant material to a remaining portion of said surface of said chip scale semiconductor package;
curing said encapsulant material; and
removing at least a portion of said layer of material from at least a portion of said surface of said chip scale semiconductor package. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
providing a heat sink having at least one surface; and
securing said heat sink to said surface of said chip scale semiconductor package.
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24. The method of claim 16, wherein said silicon gel material includes a gel elastomer material filled with heat conductive particles whereby heat conductivity is enhanced.
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25. The method of claim 24, wherein said heat conductive particles include metal particles, carbon particles, and diamond-filled thermally conductive material in particle form.
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26. The method of claim 15, wherein said layer of material includes a dam extending a portion of a length of at least one side of said chip scale semiconductor package.
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27. The method of claim 26, wherein said dam extends a portion of a length of a plurality of sides of said chip scale semiconductor package.
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28. A method for preventing at least a portion of glob top material from adhering to at least a portion of a surface of a semiconductor die, comprising:
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applying a first layer of material to said surface of said semiconductor die, said first layer of material including at least one of a gel, a material having a filler therein, and an elastomeric material;
applying a second layer of material as a mask to a portion of a surface of said first layer of material;
applying an encapsulant material to a remaining portion of said surface of said semiconductor die;
curing said encapsulant material; and
removing at least a portion of said first layer of material from at least a portion of said surface of said semiconductor die. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
providing a heat sink having at least one surface; and
securing said heat sink to a surface of said second layer of material.
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37. The method of claim 29, wherein said silicon gel material includes a gel elastomer material filled with heat conductive particles whereby heat conductivity is enhanced.
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38. The method of claim 37, wherein said heat conductive particles include metal particles, carbon particles, and diamond-filled thermally conductive material in particle form.
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39. The method of claim 28, wherein said second layer of material includes a dam extending a portion of a length of at least one side of said semiconductor die.
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40. The method of claim 39, wherein said dam extends a portion of a length of a plurality of sides of said semiconductor die.
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41. A method for preventing at least a portion of glob top material from adhering to at least a portion of a surface of a semiconductor die, comprising:
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applying a layer of material as a mask to a portion of said surface of said semiconductor die said layer including at least one of a gel, a material having a filler therein, and an elastomeric material;
applying glob top material to a remaining portion of said surface of said semiconductor die;
curing said glob top material; and
removing at least a portion of said layer of material from at least a portion of said surface of said semiconductor die. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
providing a heat sink having at least one surface; and
securing said heat sink to said surface of said semiconductor die.
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50. The method of claim 42, wherein said silicon gel material includes a gel elastomer material filled with heat conductive particles whereby heat conductivity is enhanced.
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51. The method of claim 50, wherein said heat conductive particles include metal particles.
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52. The method of claim 41, wherein said layer of material includes a dam extending a portion of a length of one side of said semiconductor die.
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53. The method of claim 52, wherein said dam extends a portion of a length of a plurality of sides of said semiconductor die.
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54. A method for fabricating a Chip On Board semiconductor device with a heat sink, said method comprising:
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providing a semiconductor die having a first side, a second side, and edges therebetween;
providing a substrate;
providing a thermally conductive heat sink member;
attaching at least a portion of said first side of said semiconductor die to a portion of said substrate;
covering at least a portion of said second side of said semiconductor die with a material having an exposed surface, said material including at least one of a gel, a material having a filler therein and an elastomeric material;
applying a material to encapsulate said edges of said semiconductor die;
maintaining said exposed surface of said material covering said at least a portion of said second side of said semiconductor die substantially unencapsulated;
curing said material to encapsulate said edges of said semiconductor die;
removing said material having an exposed surface covering said at least a portion of said second side of said semiconductor die; and
attaching a portion of said heat sink member to at least a portion of said second side of said semiconductor die. - View Dependent Claims (55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
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65. A method for preventing at least a portion of a glob top material from adhering to at least a portion of a surface of a semiconductor die, comprising:
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applying a layer of at least one of a material having filler therein and a gel elastomer material as a mask to a portion of said surface of said semiconductor die;
applying glob top material to the remaining portion of said surface of said semiconductor die;
curing said glob top material; and
peeling at least a portion of said gel elastomer material from at least a portion of said surface of said semiconductor die. - View Dependent Claims (66, 67, 68)
attaching a surface of a heat sink to said surface of said semiconductor die.
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68. The method of claim 67, wherein said gel elastomer material includes a gel elastomer material filled with particles.
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69. A method for fabricating a Chip On Board semiconductor device having a heat sink, said method comprising:
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providing a semiconductor die having a first side, a second side, edges therebetween, and electrical terminals;
providing a substrate having electrical connections;
providing a thermally conductive heat sink member;
attaching at least a portion of said first side of said semiconductor die to at least a portion of said substrate;
connecting at least one electrical terminal of said electrical terminals of said semiconductor die to at least one electrical connection of said electrical connections of said substrate;
covering at least a portion of said second side of said semiconductor die with a compliant protective layer having an exposed surface, said layer comprising at least one of a material having a filler therein and an elastomer;
applying a material to encapsulate said at least one electrical terminal of said electrical terminals and at least one edge of said edges of said semiconductor die;
maintaining at least a portion of said exposed surface of said protective layer substantially unencapsulated by said material;
curing said material;
removing at least a portion of said protective layer; and
attaching a portion of said heat sink member to a portion of said second side of said semiconductor die.- View Dependent Claims (70, 71, 72, 73, 74, 75, 76, 77, 78, 79)
connecting said electrical terminals of said semiconductor die includes wirebonding said electrical terminals of said semiconductor die to said electrical connections of said substrate.
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71. The method of claim 70, wherein said heat sink member is attached to said second side of said semiconductor die between said electrical terminals of said semiconductor die.
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72. The method of claim 69, wherein providing a semiconductor die includes providing a semiconductor die having an active surface with a grid of circuit connections configured for bonding to said substrate;
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connecting said electrical terminals of said semiconductor die to said electrical connections of said substrate includes bonding said grid of circuit connections to said electrical connections on said substrate.
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73. The method of claim 72, wherein said heat sink member is attached to a non-active back side surface of said semiconductor die.
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74. The method of claim 69, wherein said substrate is a printed circuit board.
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75. The method of claim 69, wherein covering said at least a portion of said second side of said semiconductor die includes covering said at least a portion of said second side of said semiconductor die with a thermally conductive gel elastomer filled with thermally conductive particles.
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76. The method of claim 75, wherein said gel elastomer filled with thermally conductive particles comprises cross-linked silicone.
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77. The method of claim 75, wherein said gel elastomer filled with thermally conductive particles includes a gel elastomer filled with metal particles.
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78. The method of claim 77, wherein attaching said heat sink member includes attaching said heat sink member to said second side of said semiconductor die with a non-stress thermally conductive adhesive.
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79. The method of claim 78, wherein attaching said heat sink member includes attaching said heat sink member to said second side of said semiconductor die with a polymeric tape.
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80. A fabrication method for a semiconductor device assembly having a heat sink, said method comprising:
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providing a semiconductor die having a first side, a second side, and edges therebetween;
providing a substrate;
providing a thermally conductive heat sink member;
attaching at least a portion of said first side of said semiconductor die to at least a portion of said substrate;
covering at least a portion of said second side of said semiconductor die with a material having an exposed surface, said material comprising at least one of a material having a filler therein and an elastomeric material;
applying a material to encapsulate at least a portion of one edge of said edges of said semiconductor die;
maintaining said exposed surface of said material covering said at least a portion of said second side of said semiconductor die substantially unencapsulated;
curing said material to encapsulate said at least a portion of one edge of said edges of said semiconductor die;
removing at least a portion of said material having an exposed surface covering said at least a portion of said second side of said semiconductor die; and
attaching at least a portion of said heat sink member to a portion of said second side of said semiconductor die. - View Dependent Claims (81, 82, 83, 84, 85, 86, 87, 88, 89, 90)
wirebonding said wire bond pads of said semiconductor die to said substrate.
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82. The method of claim 81, wherein said heat sink member is attached to said semiconductor die between said wire bond pads of said semiconductor die.
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83. The method of claim 80, wherein providing a semiconductor die includes providing a semiconductor die having a surface having a grid of circuit connections configured for downbonding to said substrate;
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attaching said semiconductor die to said substrate includes attaching said grid of circuit connections to said substrate.
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84. The method of claim 83, wherein said heat sink member is attached to a non-active back side surface of said semiconductor die.
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85. The method of claim 80, wherein said substrate is a printed circuit board.
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86. The method of claim 80, wherein covering said at least a portion of said second side of said semiconductor die comprises covering said at least a portion of said second side of said semiconductor die with a thermally conductive gel elastomer filled with thermally conductive particles.
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87. The method of claim 86, wherein said thermally conductive gel elastomer comprises cross-linked silicone.
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88. The method of claim 86, wherein said thermally conductive gel elastomer is filled with metal particles.
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89. The method of claim 80, wherein attaching said heat sink includes attaching said heat sink member to said second side of said semiconductor die with a thermally conductive adhesive.
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90. The method of claim 80, wherein attaching said heat sink includes attaching said heat sink member to said second side of said semiconductor die with a polymeric tape.
Specification