Chip package structure and chip packaging method

Embodiments of the present invention provide a chip package structure and a chip packaging method, which is related to the field of electronic technologies, and can protect chips and effectively dissipate heat for chips. The chip package structure includes a substrate, chips, and a heat dissipating lid, where the chips include at least one master chip disposed on the substrate and at least one slave chip disposed on the substrate; the heat dissipating lid is bonded to the slave chip by using a heat conducting material, and the heat dissipating lid covers the at least one slave chip; and the heat dissipating lid includes a heat dissipating window at a position corresponding to the at least one master chip. The embodiments of the present invention are applicable to multi-chip packaging.

TECHNICAL FIELD

The present invention relates to the field of electronic technologies, and in particular, to a chip package structure and a chip packaging method.

BACKGROUND

Nowadays, chip heat dissipation has become one of the bottlenecks in chip design. For chip heat dissipation, in addition to using hardware (a heat sink) to achieve heat dissipation of a chip, the design of the chip also has a significant effect on heat dissipation. For the heat generated by the chip itself, a small part of the heat is dissipated out from a bottom substrate and welding joints, and most of the heat is dissipated from a surface of the chip. Therefore, currently, a heat dissipating lid is usually added on top of the chip in a chip package design. This kind of heat dissipating lid usually has two designs: one is bonding the heat dissipating lid to the chip and the substrate by using a heat conducting material to form a sealed package structure; and the other is directly bonding the heat dissipating lid to the chip by using a heat conducting material without contacting the substrate. Further, in addition to adding a heat dissipating lid on top of the chip to dissipate heat for the chip, the chip may also be directly exposed to the outside, with a heat sink directly contacting the chip by using the heat conducting material to dissipate heat.

However, in multi-chip package design, because chips include both master chips and slave chips, different functions of the chips result in different corresponding power consumption. Because a master chip is mainly a logic operation chip with high power consumption, it requires relatively high heat dissipation performance. A slave chip, however, is generally a memory chip with low power consumption, and accordingly requires relatively low heat dissipation performance. Therefore, a chip package structure with a heat dissipating lid cannot dissipate heat for a chip efficiently, while a chip in a chip package structure without a heat dissipating lid is exposed to a high risk of cracking, and the chip easily cracks.

SUMMARY

Embodiments of the present invention provide a chip package structure and a chip packaging method, which can protect chips and effectively dissipate heat for chips.

In order to achieve the above objective, the following technical solutions are adopted in the embodiments of the present invention.

According to a first aspect, a chip package structure is provided, including a substrate, chips, and a heat dissipating lid, where

the chips include at least one master chip disposed on the substrate and at least one slave chip disposed on the substrate; and

the heat dissipating lid is bonded to the slave chip by using a heat conducting material, and the heat dissipating lid covers the at least one slave chip; and the heat dissipating lid includes a heat dissipating window at a position corresponding to the at least one master chip.

In a first possible implementation manner, according to the first aspect, the chip package structure further includes a heat sink, where

the heat sink is bonded to the at least one master chip by using a heat conducting material on each master chip at the heat dissipating window, and is bonded to the heat dissipating lid by using a heat conducting material on the heat dissipating lid.

In a second possible implementation manner, according to the first aspect, the heat dissipating lid includes a first packaging strip that is located at edges of a periphery of the heat dissipating lid and disposed on the substrate side, where the first packaging strip is bonded to the substrate by using a bonding material.

In a third possible implementation manner, according to the second possible implementation manner, the heat dissipating lid further includes:

a second packaging strip that is located on a periphery of the at least one master chip and disposed on the substrate side, where the second packaging strip is bonded to the substrate by using a bonding material.

In a fourth possible implementation manner, with reference to the first aspect, or the first possible implementation manner, or the second possible implementation manner, or the third possible implementation manner, the heat sink further includes: a boss structure located inside a heat dissipating window corresponding to a position of each master chip, and each of the boss structures is bonded to the corresponding master chip by using a heat conducting material on each master chip.

In a fifth possible implementation manner, with reference to the first aspect, or the first possible implementation manner, or the second possible implementation manner, or the third possible implementation manner, the chip package structure further includes a heat transfer sheet that is located at a heat dissipating window between the heat sink and each master chip. Each transfer sheet is bonded to the heat sink by using a heat conducting material between the heat transfer sheet and the heat sink, and each transfer sheet is bonded to the corresponding master chip by using a heat conducting material between the heat transfer sheet and the corresponding master chip.

In a sixth possible implementation manner, with reference to the first aspect, or the first possible implementation manner, or the second possible implementation manner, or the third possible implementation manner, or the fourth possible implementation manner, or the fifth possible implementation manner, an area of the heat dissipating window is greater than or equal to an upper surface area of the corresponding master chip.

In a seventh possible implementation manner, according to the sixth possible implementation manner, the heat conducting material is a heat-dissipation interface material.

According to a second aspect, a chip packaging method is provided, including:

coating a layer of heat conducting material on at least one slave chip of a substrate, and bonding a heat dissipating lid to the at least one slave chip.

In a first possible implementation manner, according to the second aspect, the packaging method further includes:

coating a layer of heat conducting material on the heat dissipating lid and at least one master chip of the substrate, bonding the heat sink to the at least one master chip of the substrate, and bonding the heat sink to the heat dissipating lid.

In a second possible implementation manner, according to the second aspect, if the heat dissipating lid includes a first packaging strip that is located at edges of a periphery of the heat dissipating lid and disposed on the substrate side, the packaging method further includes:

coating a layer of bonding material on the substrate at a position corresponding to the first packaging strip, and bonding the first packaging strip of the heat dissipating lid to the substrate.

In a third possible implementation manner, according to the second possible implementation manner, if the heat dissipating lid further includes a second packaging strip that is located on a periphery of the at least one master chip and disposed on the substrate side, the packaging method further includes:

coating a layer of bonding material on the substrate at a position corresponding to the second packaging strip, and bonding the second packaging strip of the heat dissipating lid to the substrate.

In a fourth possible implementation manner, with reference to the second aspect, or the first possible implementation manner, or the second possible implementation manner, or the third possible implementation manner, if a chip package structure further includes a heat transfer sheet that is located at a heat dissipating window between the heat sink and each master chip, the packaging method further includes:

coating a layer of heat conducting material on each master chip of the substrate, and bonding the heat transfer sheet to each master chip; and

coating a layer of heat conducting material on each transfer sheet, and bonding the heat sink to each transfer sheet.

In the chip package structure and the packaging method provided in the embodiments of the present invention, a heat dissipating lid is bonded to a slave chip by using a heat conducting material, a heat dissipating window is opened on the heat dissipating lid at a position corresponding to each master chip, and a heat sink is bonded to the master chip by using a heat conducting material on each master chip at the heat dissipating window and is bonded to the heat dissipating lid by using a heat conducting material on the heat dissipating lid, thereby protecting the chips and effectively dissipating heat for the chips.

DETAILED DESCRIPTION

In existing multi-chip package designs, such as system in a package (System In a Package, SIP for short), multiple chips or components required by an electronic system are generally integrated in one package. In a typical multi-chip SIP structure, at least one slave chip is distributed around a master chip. For these chips, different functions result in different corresponding power consumption. Because a master chip is mainly a logic operation chip with high power consumption, it requires relatively high heat dissipation performance. A slave chip, however, is generally a memory chip with low power consumption, and therefore requires relatively low heat dissipation performance. Therefore, an existing design with a heat dissipating lid on the chip is not suitable for the chip package structure. The embodiments of the present invention provide a chip package structure, where a heat dissipating lid has different designs according to different chips. As shown inFIG. 1, a chip package structure provided by the present invention includes a substrate1, chips2and a heat dissipating lid3.

The chips2include at least one master chip21disposed on the substrate and at least one slave chip22disposed on the substrate.

As shown inFIGS. 2a, 2b, 3a, and 3b, the chips2are placed on the substrate in two structures: symmetrical structure and asymmetrical structure. In the symmetrical structure, the master chip21is generally placed in a central position of the substrate1, and other slave chips22are laid flat around the master chip21. In the asymmetrical structure, the substrate1generally has only one master chip21and one slave chip22, and the slave chip22is memory chips stacked together by using a TSV (Through Silicon Via) technology. With memory chips stacked together, this structure has less power consumption, but correspondingly, is more fragile, and needs corresponding protection from a heat dissipating lid.

The heat dissipating lid3is bonded to a slave chip22by using a heat conducting material5. The heat dissipating lid3covers at least one slave chip22. The heat dissipating lid3includes a heat dissipating window31at a position corresponding to the at least one master chip22(that is, heat dissipating windows31may be opened on the heat dissipating lid3at positions corresponding to all master chips22, or heat dissipating windows31may be opened on the heat dissipating lid3selectively at positions corresponding to one or more master chips22).

Optionally, an area of the heat dissipating window31is greater than or equal to an upper surface area of the corresponding master chip21. In this way, heat dissipating windows31are opened on the heat dissipating lid3, so that the heat dissipation efficiency of the master chip21with high power consumption can be effectively improved, and the slave chip22with low power consumption is protected from cracking.

Further optionally, the heat dissipating lid3includes a first packaging strip32that is located at edges of a periphery of the heat dissipating lid3and disposed on the substrate1side, and the first packaging strip32is bonded to the substrate1by using a bonding material6.

Further, optionally, the heat dissipating lid3further includes a second packaging strip33that is located on a periphery of the at least one master chip21and disposed on the substrate1side, and the second packaging strip33is bonded to the substrate1by using the bonding material6.

Specifically, as shown inFIGS. 1, 4, 5, and 6, the heat dissipating lid3has the following three structures: first, a heat dissipating lid structure directly added to an upper surface of the slave chip22by using the heat conducting material5; second, a heat dissipating lid structure directly added to the upper surface of the slave chip22by using the heat conducting material5and formed by the heat dissipating lid3and the first packaging strip32that is located at edges of the periphery of the heat dissipating lid3and disposed on the substrate1side; and third, a heat dissipating lid structure directly added to the upper surface of the slave chip22by using the heat conducting material5and formed by the heat dissipating lid3, the first packaging strip32that is located at edges of the periphery of the heat dissipating lid3and disposed on the substrate1side, and the second packaging strip33that is located on the periphery of at least one master chip21and disposed on the substrate1side.

Further optionally, as shown inFIGS. 7 and 8, the chip package structure further includes a heat sink4.

The heat sink4is bonded to the at least one master chip21by using the heat conducting material5on each master chip21at the heat dissipating window31, and is bonded to the heat dissipating lid3by using the heat conducting material5on the heat dissipating lid3.

Further, optionally, as shown inFIG. 7, the heat sink4further includes a boss structure41located inside the heat dissipating window31that corresponds to a position of each master chip21, and each boss structure41separately is bonded to the corresponding master chip21by using the heat conducting material5on each master chip21.

Further, optionally, as shown inFIG. 8, the chip package structure further includes a heat transfer sheet42located at the heat dissipating window31between the heat sink4and each master chip21. Each heat transfer sheet42is bonded to the heat sink4by using the heat conducting material5between the heat transfer sheet42and the heat sink4, and each heat transfer sheet42is bonded to the corresponding master chip21by using the heat conducting material5between the heat transfer sheet42and the corresponding master chip21.

The above boss structure and heat transfer sheet are disposed to avoid a height difference between the master chip and the heat dissipating lid, where the height difference results in a gap between the heat sink and the master chip to let air enter when the heat sink is installed, and air is a poor conductor of heat that hinders heat from transmitting from the master chip to the heat sink. Therefore, the boss structure or heat transfer sheet is added between the master chip and the heat sink to eliminate the height difference between the master chip and the heat dissipating lid.

Specifically, as shown inFIG. 7, when the heat sink4further includes the boss structure41located inside the heat dissipating window31corresponding to a position of each master chip21, the boss structure41is directly bonded to the corresponding master chip21by using the heat conducting material5on each master chip21; and when the heat sink4does not include the boss structure41, as shown inFIG. 8, the chip package structure further includes the heat transfer sheet42located at the heat dissipating window31between the heat sink4and each master chip21. The heat transfer sheet42is bonded to the corresponding master chip21by using the heat conducting material5between the heat transfer sheet42and the corresponding master chip21, and is bonded to the heat sink4by using the heat conducting material5between the heat transfer sheet42and the heat sink4.

Optionally, the heat conducting material5mentioned in the embodiments of the present invention is a heat-dissipation interface material. The heat-dissipation interface material is generally a thermally conductive silicone. This kind of heat-dissipation interface material can not only decrease a thermal contact resistance generated between a heat source surface and a contact surface of a heat sink component, but also perfectly fill a gap between the contact surfaces to squeeze air out of the contact surfaces, thereby preventing the air between the contact surfaces (air is a poor conductor of heat) from hindering heat from transmitting between contact surfaces. In addition, with the supplement of the heat-dissipation interface material, the contact between contact surfaces is better, and a real face-to-face contact is achieved. In addition, the heat-dissipation interface material is generally further used as a bonding agent to perform a bonding function between components.

In the chip package structure provided in the embodiments of the present invention, a heat dissipating lid is bonded to a slave chip by using a heat conducting material, a heat dissipating window is opened on the heat dissipating lid at a position corresponding to each master chip, and a heat sink is bonded to the master chip by using a heat conducting material on each master chip at the heat dissipating window and is bonded to the heat dissipating lid by using a heat conducting material on the heat dissipating lid, thereby protecting the chips and effectively dissipating heat for the chips.

An embodiment of the present invention specifically describes a chip packaging method. As shown inFIG. 9, the packaging method includes the following steps:

101: Coat a layer of heat conducting material on at least one slave chip of a substrate, and bond a heat dissipating lid to the at least one slave chip.

A specific bonding process is: firstly coat or place the heat conducting material on the at least one slave chip, bond the heat dissipating lid to the heat conducting material according to orientation, and solidify the heat conducting material after the heat dissipating lid is bonded, where solidification temperature is generally about 150° C., and a solidification duration is generally between half an hour and two hours.

The heat dissipating lid needs to be prepared before step101, and then the processing in the subsequent step101is performed. Materials for preparing the heat dissipating lid need to be determined before the heat dissipating lid is prepared. The materials for preparing the heat dissipating lid include copper, copper alloy or AlSiC aluminum silicon carbide. When the material for preparing the heat dissipating lid is copper or copper alloy, proceed to step a1, and when the material for preparing the heat dissipating lid is AlSiC aluminum silicon carbide, proceed to step b1.

Specifically, a preparation process of the heat dissipating lid is as follows:

a1. Select a copper block of a corresponding size, and mill the copper block into a shape corresponding to the heat dissipating lid;

a2. Mill a heat dissipating window at a position corresponding to a master chip where the heat dissipating lid is not needed; and

a3. Plate a nickel layer on the milled heat dissipating lid in an electroplating bath to protect the copper from oxidization.

The heat dissipating lid is prepared by adopting a casting method, and the specific steps are as follows:

b1. Make a mold that is the same as the heat dissipating lid according to a shape and a size of the heat dissipating lid; and

b2. Pour a mixture of aluminum and SiC silicon carbide in the mold in high temperature, cool it to room temperature, and take out the heat dissipating lid.

Further, optionally, if the heat dissipating lid in step101further includes a first packaging strip that is located at edges of a periphery of the heat dissipating lid and disposed on the substrate side, step101further includes:

101a. Coat a layer of bonding material on the substrate at a position corresponding to the first packaging strip, and bond the first packaging strip of the heat dissipating lid to the substrate.

Further optionally, if the heat dissipating lid in step101further includes a second packaging strip that is located on a periphery of the at least one master chip and disposed on the substrate side, step101further includes:

101b: Coat a layer of bonding material on the substrate at a position corresponding to the second packaging strip, and bond the second packaging strip of the heat dissipating lid to the substrate.

The above bonding material is mainly used to bond the heat dissipating lid together with the substrate, and may be an epoxy resin bonding agent, low-temperature glass, and another material used for bonding.

Optionally, as shown inFIG. 10, the chip packaging method further includes:

102. Coat a layer of heat conducting material on the heat dissipating lid and at least one master chip of the substrate, bond the heat sink to the at least one master chip of the substrate, and bond the heat sink to the heat dissipating lid.

Specifically, when the heat sink is installed, the heat sink may be bonded by using the heat conducting material, the heat sink may also be installed on the heat dissipating lid in a mechanical fastening manner, for example, using a screw for installation.

In the chip packaging method provided in the embodiments of the present invention, a heat dissipating lid is bonded to a slave chip by using a heat conducting material, a heat dissipating window is opened on the heat dissipating lid at a position corresponding to each master chip, and a heat sink is bonded to the master chip by using a heat conducting material on each master chip at the heat dissipating window and is bonded to the heat dissipating lid by using a heat conducting material on the heat dissipating lid, thereby protecting the chips and effectively dissipating heat for the chips.

The present invention provides another chip packaging method. As shown inFIG. 11, steps of the packaging method are as follows:

201: Coat a layer of heat conducting material on at least one slave chip of a substrate, and bond a heat dissipating lid to the at least one slave chip.

A specific bonding process is: firstly coat or place the heat conducting material on the at least one slave chip, bond the heat dissipating lid to the heat conducting material according to orientation, and solidify the heat conducting material after the heat dissipating lid is bonded, where solidification temperature is generally about 150° C., and a solidification duration is generally between half an hour and two hours. In addition, the heat dissipating lid needs to be prepared before step201, and the method for preparing the heat dissipating lid is the same as what is described in the preceding embodiment, which is not described herein again.

Further, optionally, if the heat dissipating lid in step201further includes a first packaging strip that is located at edges of a periphery of the heat dissipating lid and disposed on the substrate side, step201further includes:

201a. Coat a layer of bonding material on the substrate at a position corresponding to the first packaging strip, and bond the first packaging strip of the heat dissipating lid to the substrate.

Further, optionally, if the heat dissipating lid in step201further includes a second packaging strip that is located on a periphery of at least one master chip and disposed on the substrate side, step201further includes:

201b: Coat a layer of bonding material on the substrate at a position corresponding to the second packaging strip, and bond the second packaging strip of the heat dissipating lid to the substrate.

The above bonding material is mainly used to bond the heat dissipating lid together with the substrate, and may be an epoxy resin bonding agent, low-temperature glass, and another material used for bonding.

Optionally, as shown inFIG. 12, if the chip package structure further includes a heat transfer sheet at the heat dissipating window between the heat sink and each master chip, the chip packaging method further includes step202and step203.

202: Coat a layer of heat conducting material on each master chip of the substrate, and bond the heat transfer sheet to each master chip.

In addition, because there is a heat dissipating window between the master chip and the heat dissipating lid, step201and step202are not subject to a specific sequence. That is, the heat transfer sheet may be bonded first, or the heat dissipating lid may be bonded first.

203: Coat a layer of heat conducting material on each heat transfer sheet and heat dissipating lid, and bond the heat sink to each heat transfer sheet and the heat dissipating lid.

In the chip packaging method provided in the embodiments of the present invention, a heat dissipating lid is bonded to a slave chip by using a heat conducting material, a heat dissipating window is opened on the heat dissipating lid at a position corresponding to each master chip, and a heat sink is bonded to the master chip by using a heat conducting material on each master chip at the heat dissipating window and is bonded to the heat dissipating lid by using a heat conducting material on the heat dissipating lid, thereby protecting the chips and effectively dissipating heat for the chips.