Flip chip pre-assembly underfill process
First Claim
Patent Images
1. A method of forming an encapsulated array of solder bumps on a chip, the method comprising:
- (a) patterning a set of solder bumps onto said chip;
(b) coating said solder bumps in a layer of an encapsulation material, said encapsulation material substantially covering said set of solder bumps on said chip;
(c) heating said encapsulation material at a sufficient temperature and for a sufficient length of time that said encapsulation material stiffens to a substantially non-pliable solid; and
(d) removing a portion of said layer of said encapsulation material to expose a conductive portion of each of said encapsulated solder bumps while the encapsulation material is on the chip.
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Accused Products
Abstract
An encapsulation process for flip-chip bonding chips to a substrate encapsulates solder balls on the chip in a separate encapsulation process in which the chip is coated with encapsulation layer and then a portion of the encapsulation layer is removed to expose a portion of the solder balls.
114 Citations
20 Claims
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1. A method of forming an encapsulated array of solder bumps on a chip, the method comprising:
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(a) patterning a set of solder bumps onto said chip;
(b) coating said solder bumps in a layer of an encapsulation material, said encapsulation material substantially covering said set of solder bumps on said chip;
(c) heating said encapsulation material at a sufficient temperature and for a sufficient length of time that said encapsulation material stiffens to a substantially non-pliable solid; and
(d) removing a portion of said layer of said encapsulation material to expose a conductive portion of each of said encapsulated solder bumps while the encapsulation material is on the chip.
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2. A method of forming an encapsulated array of solder bumps on a first sample that may be bonded to another sample, the method comprising:
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(a) patterning a set of solder bumps onto said first sample;
(b) coating said solder bumps in a layer of an encapsulation material comprising an epoxy material, said encapsulation material substantially covering said set of solder bumps on said first sample;
(c) heating said encapsulation material at a sufficient temperature and for a sufficient length of time that said encapsulation material stiffens to a substantially non-pliable solid which is hardened to a b-stage; and
(d) removing a portion of said layer of said b-stage encapsulation material to expose a conductive portion of each of said encapsulated solder bumps. - View Dependent Claims (3, 4, 5, 6, 7, 8)
patterning solder pads on the polished surface of said chemically mechanically polished solder bumps.
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6. The method of claim 5, wherein said patterned solder pads are formed using a solder ink.
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7. The method of claim 5, wherein said solder pads are in the form of a deposited layer of solder.
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8. The method of claim 2, wherein the solder bumps are solder balls.
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9. A method of forming encapsulated solder joints in an array of solder joints formed between a chip and a substrate, comprising the steps of:
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(a) patterning a first set of solder balls onto a first set of contact regions of the chip;
(b) coating the chip with a chip encapsulation material, said chip encapsulation material substantially covering said first set of solder balls disposed on said chip;
(c) removing a portion of said chip encapsulation material to expose a conductive surface portion of each of said first set of solder balls;
(d) patterning a second set of solder balls onto a second set of contact regions on the substrate;
(e) bringing said first set of solder balls on said chip into contact with said second set of solder balls on said substrate; and
(f) heating said chip and said substrate at a sufficient temperature for said first and second set of solder balls to reflow into solder joints. - View Dependent Claims (10, 11, 12, 13, 14)
coating the substrate with a substrate encapsulation material, said substrate encapsulation material substantially covering said second set of solder balls disposed on said substrate; and
removing a portion of said substrate encapsulation material to expose a conductive portion of each said second set of solder balls.
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12. The method of claim 11, wherein said step for removing a portion of said substrate encapsulation material comprises the step of planarizing the encapsulated substrate by chemical mechanical polishing the encapsulated substrate to a common plane extending through a portion of said first set of solder balls.
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13. The method of claim 12, wherein said substrate encapsulation material and said chip encapsulation material are composed of an epoxy that is heated to the b-stage and wherein the step (f) of heating said chip and said substrate is conducted at a sufficient temperature and with a sufficient pressure between said chip and said substrate so that said epoxy encapsulation layers are bonded together.
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14. The method of claim 12, further including the step of patterning a solder pad over each said planarized second set of solder balls after said second set of solder balls are planarized.
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15. A method of bonding a chip to a substrate, comprising the steps of:
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(a) patterning a first set of solder balls onto a set of contact regions of the chip;
(b) coating the chip with a first layer of epoxy, said epoxy substantially covering said first set of solder balls disposed on said chip;
(c) heating said chip at a sufficient temperature for a sufficient time to convert said first layer of epoxy into a b-stage epoxy;
(d) planarizing said first layer of epoxy to reveal an exposed conductive surface portion of each said first set of solder balls;
(e) patterning a second set of solder balls onto a second set of contact regions on the substrate;
(f) coating the substrate with a second layer of epoxy, said epoxy substantially covering said second set of solder balls disposed on said substrate;
(g) heating said substrate at a sufficient temperature for a sufficient time to convert said second layer of epoxy into a b-stage epoxy;
(h) planarizing said second layer of epoxy to reveal a conductive surface portion of each said second set of solder balls;
(i) bringing said first set of solder balls on said chip into contact with said second set of solder balls on said substrate; and
(j) applying a sufficient pressure between said chip and said substrate at a sufficient temperature and for a sufficient time to bond said first layer of epoxy to said second layer of epoxy and reflowing said solder balls into solder joints. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification