CN105762133B - A kind of stack encapsulation structure and its process - Google Patents

Abstract

The invention relates to a stacked package structure and a process method thereof, the structure comprising a first package body (1) and a second package body (2), the first package body (1) comprising a first substrate (14) and the first chip (16), the first substrate (14) includes a first copper pillar (11), and the upper surface of the first molding compound (17) above the first substrate corresponds to the first copper pillar (11) An opening (18) is provided at the position, a solder ball (13) is provided on the top of the first copper pillar (11), and the second package (2) includes a second substrate (19), a second chip (20) and the second molding compound (21), the second substrate (19) is provided with a second copper pillar (12) on the lower surface, and the second copper pillar (12) is inserted on the first molding compound (17) in the opening (18). The invention discloses a stacked packaging structure and a process method thereof, which can prevent solder balls from bridging during reflowing, thereby improving the yield rate of products.

Description

A stacked packaging structure and its manufacturing method

technical field

The invention relates to a stacked packaging structure and a process method thereof, belonging to the technical field of semiconductor packaging.

Background technique

With the vigorous development of portable electronic products in recent years, all kinds of related products are gradually moving towards the trend of high density, high performance, light, thin, short and small, and various types of package stacking (package on package, PoP). Cooperate with innovation, in order to meet the requirements of thin, light, small and high density.

As shown in FIG. 1 , it is a schematic cross-sectional view of an existing POP packaging structure. The package stacking device includes two stacked package structures 100 and another package structure 200 . After the first package 100 is formed, the upper surface of the first package is thinned to expose the copper pillars 101 , and the second package 200 is stacked and electrically connected to the lower package 100 by means of the solder balls 201 on the backside of the substrate.

The above-mentioned stacking structure has the following defects:

1. With the miniaturization of electronic components, the distance between the lines in the package becomes smaller, and the distance between the solder balls needs to be reduced, so that the adjacent solder balls are prone to bridging;

2. The volume and height tolerance of the solder balls after reflow is large. During reflow, the solder balls will first become soft and collapsed. At the same time, after bearing the weight of the package body 200 above, they are easy to collapse and deform, and bridging occurs;

3. The grid array formed by the solder balls is likely to have poor coplanarity, resulting in unbalanced stress on the contacts and easily causing the stacked structure to tilt.

Contents of the invention

The technical problem to be solved by the present invention is to provide a stacked packaging structure for the above prior art, so that the solder balls during reflow can avoid bridging phenomenon, so as to improve the yield of products and meet the requirements of fine pitch.

Another object of the present invention is to provide a stacked packaging structure with good coplanarity, easy to control product height, and no tilting;

Another object of the present invention is to provide a process method of a stacked packaging structure, so that the solder balls of the stacked structure can avoid bridging during reflow, so as to improve the yield of the process.

The technical solution adopted by the present invention to solve the above problems is: a stacked packaging structure, which includes a first package and a second package, the first package includes a first substrate and a first chip, the first The substrate includes a first circuit pattern and a first copper pillar, a first molding compound is arranged above the first substrate, and openings are arranged on the upper surface of the first molding compound corresponding to the positions of the first copper pillars, and the first copper The top of the post is exposed in the opening on the upper surface of the first molding compound, the top of the first copper post is provided with solder balls, the second package includes a second substrate, a second chip and a second molding compound, the first A second copper column is arranged on the lower surface of the second substrate, and the second copper column is inserted into the opening on the first molding compound, and is electrically connected to the first copper column through solder balls.

The first chip is electrically connected to the first circuit pattern in the first substrate, and the upper surfaces of the first chip and the first circuit pattern are located inside the first molding compound.

The tops of the first copper pillar and the second copper pillar have a convex structure.

The first molding compound and the second molding compound are filled or unfilled epoxy resins.

A process method for a stacked packaging structure, the method comprising the following steps:

Step 1, taking the first metal substrate;

Step 2: Paste photoresist films that can be exposed and developed on the front and back of the first metal substrate respectively, and use exposure and development equipment to perform pattern exposure, development and removal of part of the pattern photoresist film on the front of the metal substrate to expose the first metal substrate Etching the first metal substrate to form the first copper pillar in the area pattern that needs to be etched subsequently on the front side;

Step 3: Paste a photoresist film that can be exposed and developed on the front of the first metal substrate in step 2, and use the exposure and development equipment to perform graphic exposure, development and removal of part of the graphic photoresist film on the front of the first metal substrate again to expose the first metal substrate. A region pattern to be subsequently etched on the front of the metal substrate, etching the first metal substrate to form a first circuit pattern, and removing the photoresist film on the surface of the first metal substrate;

Step 4. Place the chip on the first metal substrate that has been etched in step 3. The chip is electrically connected to the first circuit pattern, and then the front side of the first metal substrate is protected by epoxy resin molding to form a first molding compound. The upper surface of the first plastic encapsulant is higher than the upper surface of the first copper pillar;

Step 5, opening a hole at the position corresponding to the first copper pillar in the first plastic encapsulant to expose the first copper pillar;

Step 6, thinning the lower surface of the first metal substrate to separate the first circuit pattern from the first copper pillar, thereby forming a first package;

Step 7, taking the second metal substrate;

Step 8, setting a second chip on the second metal substrate in step 7, the second chip is electrically connected to the second metal substrate, and then performing epoxy resin plastic sealing protection on the front of the second metal substrate to form a second plastic packaging compound;

Step 9: Paste a photoresist film that can be exposed and developed on the back of the second metal substrate that has been encapsulated in step 8, and use the exposure and development equipment to perform pattern exposure, development and removal of part of the pattern photoresist film on the back of the second metal substrate to Exposing the pattern of the area on the back of the second metal substrate that needs to be etched subsequently, etching the second metal substrate to form a second copper pillar;

Step 10. Place solder balls in the opening of the first molding compound of the first package formed in step 6, and combine the second package formed in step 9 with the first package, so that the second package Inserting the second copper pillar on the surface into the opening on the upper surface of the first plastic molding compound of the first package;

Step eleven, performing reflow soldering, so that the second copper pillar on the lower surface of the second package is electrically connected to the first copper pillar of the first package through solder balls;

Step 12: Cutting the semi-finished product stacked in step 11 to obtain a stacked package structure.

Compared with the prior art, the present invention has the advantages of:

1. The copper pillars 11 of the first package and the copper pillars 12 of the second package of the present invention are electrically connected through solder balls in the openings, and the metal pillars contact the metal balls, so that the fusion during reflow occurs only at the The contact end of the metal post in the hole, the fusion joint is located in the hole, so the bridging phenomenon can be avoided to improve the yield of the product, and can meet the needs of fine pitch;

2. Due to the support of the metal pillars during reflow, the present invention has a small package height tolerance, less likely to produce defects in the joints, good coplanarity, easy to control the height of the product, and no inclination.

Description of drawings

FIG. 1 is a schematic diagram of an existing POP packaging structure.

FIG. 2 is a schematic diagram of a package-on-package structure of the present invention.

3 to 13 are process flow charts of a stacked packaging structure of the present invention.

14 and 15 are schematic diagrams of another embodiment of a package-on-package structure of the present invention.

in:

First Package 1

Second Package 2

First Copper Pillar 11

The second copper pillar 12

Solder ball 13

first substrate 14

First line pattern 15

first chip 16

First Molding Compound 17

Hole 18

second substrate 19

second chip 20

Second molding compound 21.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in FIG. 2, a package-on-package structure in this embodiment includes a first package body 1 and a second package body 2, and the first package body 1 includes a first substrate 14 and a first chip 16, The first substrate 14 includes a first circuit pattern 15 and a first copper pillar 11, the first circuit pattern 15 is provided with a first chip 16, and the first chip 16 is electrically connected to the first circuit pattern 15 A first molding compound 17 is provided above the first substrate 14, and an opening 18 is provided on the upper surface of the first molding compound 17 corresponding to the position of the first copper pillar 11, and the top of the first copper pillar 11 is exposed at the In the opening 18 on the upper surface of a molding compound 17, the top of the first copper pillar 11 is provided with a solder ball 13, and the second package body 2 includes a second substrate 19, a second chip 20 and a second molding compound 21, The second copper column 12 is arranged on the lower surface of the second substrate 19, and the second copper column 12 is inserted into the opening 18 on the first molding compound 17, and is connected to the first copper column 11 by the solder ball 13. form an electrical connection.

Its process steps are as follows:

Step 1, see Figure 3, take the first metal substrate;

Step 2. Referring to FIG. 4, attach a photoresist film that can be exposed and developed on the front and back of the first metal substrate, and use the exposure and development equipment to perform pattern exposure, development and removal of part of the pattern photoresist film on the front of the metal substrate to expose Etching the first metal substrate to form the first copper pillar by etching the pattern of the region that needs to be etched subsequently on the front of the first metal substrate;

Step 3, see Figure 5, paste a photoresist film that can be exposed and developed on the front of the first metal substrate in step 2, and use the exposure and development equipment to perform graphic exposure, development and removal of part of the graphic photoresist film on the front of the first metal substrate again Etching the first metal substrate to form a first circuit pattern and removing the photoresist film on the surface of the first metal substrate to expose the pattern of the area on the front surface of the first metal substrate that needs to be etched subsequently;

Step 4, see Figure 6, set the chip on the first metal substrate etched in step 3, the chip is electrically connected to the first circuit pattern, and then the front of the first metal substrate is protected by epoxy resin molding to form the second A molding compound, the upper surface of the first molding compound is higher than the upper surface of the first copper pillar, and the epoxy resin material can be selected according to product characteristics with filler or without filler;

Step 5. Referring to Figure 7, make a hole at the position where the first plastic encapsulant corresponds to the first copper pillar, in order to expose the first copper pillar;

Step 6, referring to FIG. 8 , thinning the lower surface of the first metal substrate in order to realize the separation of the first circuit pattern and the first copper pillar, thereby forming the first package;

Step 7, see Figure 9, take the second metal substrate;

Step 8, see Figure 10, set the second chip on the second metal substrate in step 7, realize electrical connection between the second chip and the second metal substrate, and then carry out epoxy resin plastic sealing protection on the front of the second metal substrate to form the second 2. Molding compound, epoxy resin material can choose the type with filler or without filler according to the product characteristics;

Step 9, see Figure 11, paste a photoresist film that can be exposed and developed on the back of the second metal substrate that has been encapsulated in step 8, and use the exposure and developing equipment to perform graphic exposure, development and removal of part of the graphic light on the back of the second metal substrate The resist film is used to expose the pattern of the area on the back of the second metal substrate that needs to be etched subsequently, and the second metal substrate is etched to form the second copper pillar;

Step 10. Referring to FIG. 12, place solder balls in the opening of the first molding compound of the first package formed in step 6, and combine the second package formed in step 9 with the first package to make the first package Inserting the second copper post on the lower surface of the second package into the opening on the upper surface of the first plastic molding compound of the first package;

Step 11. Referring to FIG. 13 , perform reflow soldering so that the second copper pillar on the lower surface of the second package is electrically connected to the first copper pillar of the first package through solder balls;

Step 12: Cutting the semi-finished product stacked in step 11 to obtain a stacked package structure.

As shown in Figure 14 and Figure 15, it is another embodiment of a stacked package structure of the present invention, which includes a first package body 1 and a second package body 2, the first copper in the first package body 1 The top of the column 11 has a convex structure, the top of the second copper column 12 on the lower surface of the second package body 2 has a convex structure, and the second copper column 12 is inserted into the opening 18 on the first molding compound 17, And form an electrical connection with the first copper pillar 11 through the solder ball 13, because the top of the first copper pillar and the top of the second copper pillar have a convex structure, during reflow soldering, the solder will completely cover the bump on the copper pillar , the bonding force between the first package and the second package can be further strengthened through the gripping force of the solder covering the bumps.

In addition to the above-mentioned embodiments, the present invention also includes other implementations, and any technical solution formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the claims of the present invention.

Claims (1)

1. a kind of process of stack encapsulation structure, it is characterised in that the described method comprises the following steps：

Step 1: taking the first metal substrate；

Step 2: stick the photoresistance film that can be exposed development respectively in the first metal substrate front and the back side, it is aobvious using exposure Metal substrate front is carried out graph exposure, development and removal partial graphical photoresistance film by shadow equipment, to expose the first metal substrate Front subsequently needs the regional graphics being etched, and is etched to the first metal substrate, forms the first copper post；

Step 3: sticking the photoresistance film that can be exposed development in the first metal substrate front of step 2, exposure imaging is utilized First metal substrate front is carried out graph exposure, development and removal partial graphical photoresistance film by equipment again, to expose the first gold medal Belong to substrate front side and subsequently need the regional graphics being etched, the first metal substrate is etched, forms first line pattern, Remove the photoresistance film of the first metallic substrate surfaces；

Step 4: chip is set on the first metal substrate for completing etching in step 3, chip is real with first line pattern It is now electrically connected, then epoxy resin plastic packaging protection is carried out to the first metal substrate front, form the first plastic packaging material, the first plastic packaging material Upper surface is higher by the upper surface of the first copper post；

Step 5: the position for corresponding to the first copper post in the first plastic packaging material carries out trepanning, the first copper post is exposed；

Step 6: the lower surface of the first metal substrate is thinned, the separation of first line pattern and the first copper post is realized, from And form the first packaging body；

Step 7: taking the second metal substrate；

Step 8: the second chip is arranged on the second metal substrate of step 7, the second chip and the second metal substrate realize electricity Property connection, then to the second metal substrate front carry out epoxy resin plastic packaging protection, formed the second plastic packaging material；

Step 9: the photoresistance film that can be exposed development is sticked at the second metal substrate back side for completing encapsulating to step 8, utilize The second metal substrate back side is carried out graph exposure, development and removal partial graphical photoresistance film by exposure imaging equipment, to expose the The two metal substrate back sides subsequently need the regional graphics being etched, and are etched to the second metal substrate, form the second copper post；

Step 10: tin ball is placed in the trepanning of the first plastic packaging material of the first packaging body that step 6 is formed, by shape in step 9 At the second packaging body and the first packaging body be combined, make the second packaging body lower surface the second copper post be inserted into the first packaging body The first plastic packaging material upper surface trepanning in；

Step 11: carry out Reflow Soldering, the second copper post of the second packaging body lower surface is made to pass through the of tin ball and the first packaging body One copper post is electrically connected；

Step 12: step 11, which is completed the semi-finished product that packaging body stacks, carries out cutting operation, stack encapsulation structure is made.