CN115020390A

CN115020390A - COB packaging mode

Info

Publication number: CN115020390A
Application number: CN202210435064.9A
Authority: CN
Inventors: 马洪毅; 付桂花; 程月鸿
Original assignee: Shanxi Gaoke Huaxing Electronic Technology Co ltd
Current assignee: Shanxi Gaoke Huaxing Electronic Technology Co ltd
Priority date: 2022-04-24
Filing date: 2022-04-24
Publication date: 2022-09-06

Abstract

The invention relates to a COB (chip on board) packaging mode, belonging to the technical field of COB packaging; replacing a die pressing encapsulation process in the existing COB encapsulation process with a film pasting process, carrying out jet printing and gap filling on a PCB before the film pasting process is carried out, then covering a layer of semi-cured film material on the surface of the PCB through a film pasting machine, then carrying out lighting test on the PCB, if the PCB is defective, carrying out film pasting again after the PCB is repaired, if the PCB is not defective, carrying out vacuum defoaming on the PCB, heating to enable the film material to be tightly attached to the PCB, and finally curing and drying the PCB to complete the plastic packaging process; the problem of adopt the mould pressing to encapsulate the defect more in the present COB encapsulation is solved.

Description

COB packaging mode

Technical Field

The invention belongs to the technical field of COB (chip on board) packaging, and particularly relates to a COB packaging mode.

Background

The COB packaging process flow adopted in the current market mainly comprises the following steps:

1. designing a PCB (printed Circuit Board): designing a corresponding chip carrier PCB according to the terminal requirement;

2. surface-removing paster: according to the design of the PCB, adhering components such as capacitors, resistors, ICs, connecting machines and the like to corresponding positions by using solder paste;

3. reflow soldering: setting corresponding temperature according to the characteristics of the solder paste, and baking and curing by reflow soldering;

4. chip pasting: a special chip die bonder is adopted, and a proper clamp and consumables are matched to fixedly place the chip at a corresponding position of the inverted PCB;

5. reflow soldering: setting corresponding temperature with the solder paste characteristic, and carrying out reflow soldering for curing;

6. repairing: for the identified bad point positions, special equipment is adopted for repairing, and the process yield is ensured to be 100%;

7. and (3) die pressing and encapsulating: matching a corresponding die according to the PCB plate type number requirement; injecting liquid epoxy resin into the die cavity through a hydraulic injection molding machine; setting proper temperature, pressure, speed and time according to the process requirements to realize rapid die pressing encapsulation; setting a proper temperature for long baking to completely cure the module encapsulating glue;

8. cutting aging test repairing assembly: cutting and assembling the edge of the PCB subjected to mould pressing and baking into a box body, and setting corresponding current, voltage and scanning frequency to perform functional test and aging on the module; when bad point positions occur, special equipment is used for repairing and then aging is carried out;

the problems mainly existing in the process of die-pressing encapsulation are as follows:

1. glue batches or glue preparation in each time have difference, so that the consistency of the glue surface color is poor, and the appearance consistency of products is influenced by obvious color difference after the box body is assembled;

2. the COB packaging single board has higher cost, and the problems of corner glue shortage, small needle holes, air bubbles, uncured glue and the like exist in the plastic packaging process, so that the whole board is scrapped;

3. the thickness deviation of the rubber surface is caused by the mould or other problems during mould pressing, and the consistency of the appearance is influenced;

4. the improper operation during the die pressing causes the defects of chip scratch, dislocation and the like of the fixed crystal, the repair is difficult after the baking, and the current repair technology is immature.

Disclosure of Invention

The invention overcomes the defects of the prior art and provides a COB packaging mode; the problem of adopt the mould pressing to encapsulate the defect more in the COB encapsulation at present is solved.

In order to achieve the above object, the present invention is achieved by the following technical solutions.

The utility model provides a COB's packaging mode, mould pressing among the COB packaging technology of having now encapsulates the technology and replaces for the pad pasting technology, before carrying out the pad pasting technology, spout the seal to the PCB board and crack, cover one deck semi-solid membrane material to the PCB board surface through the pad pasting machine after that, then light the test to the PCB board, if there is badly, then carry out the pad pasting once more after repairing the PCB board, if do not have badly, then carry out the vacuum deaeration with the PCB board, make membrane material and PCB board close laminating through the heating, solidify and dry the PCB board at last, accomplish the plastic envelope flow.

Further, the specific way of jet printing for filling joints is to fill chip gaps or pixel gaps with dark black ink through a jet printing machine, then use epoxy resin glue for filling joints, and then enter a tunnel furnace for glue drying.

Further, the semi-cured film material is a matte black optical packaging film material, mainly comprises a PET material, has 8 layers, and sequentially comprises a protective film, an anti-fingerprint protective layer, a nano anti-glare coating, a hardening treatment ink layer, a PET substrate, a hardening layer, an optical glue layer and a protective layer from top to bottom.

Further, be provided with a conveyer belt, the conveyer belt drives through batch cylinder, the direction of transfer along the conveyer belt has set gradually the sticking film machine, the electricity measures the machine of lighting, the vacuum defoaming machine, the solidification drying-machine, one side that the machine was lighted to the electricity is provided with the machine of reprocessing, bring conveying PCB board through the conveyer, carry out the pad pasting to the PCB board in sticking film machine inside, measure the quick-witted inside bad some discernment to the PCB board of lighting at the electricity, reprocess the PCB board in the machine of reprocessing inside, carry out the vacuum deaeration to the PCB board in the vacuum defoaming machine inside, solidify and dry the PCB board in the solidification drying-machine inside.

Further, when the PCB is repaired, the semi-cured film material on the PCB is removed, and the removed semi-cured film material is conveyed to the inside of the film sticking machine again for film sticking.

Further, after the semi-cured film material is removed, when the defective points are repaired, the defective points are identified, laser crystal removal is performed on the defective points, then the solder paste is removed, the solder paste is re-spotted, crystal solidification is performed again, and finally good products are obtained.

Furthermore, during the vacuum defoaming process, the semi-cured film material is attached in a two-stage manner, and heating and pressurizing are carried out in a first-stage vacuum environment, so that the semi-cured film material is filled in the gaps of the chips, and a formed product which is free of bubbles and can follow the shape is obtained; in the second stage, the laminate having the irregularities is heated again to flow and the surface is flattened by pressing.

Compared with the prior art, the invention has the following beneficial effects:

(1) due to appearance difference caused by inconsistent colloid colors caused by glue batch difference or glue mixing difference, the film material is a prefabricated semi-cured film, and the risk of difference between batches is lower than that of packaging glue.

(2) The packaging glue is frozen and stored after the incoming glue is needed, unfreezing is carried out at normal temperature before use, mixing is carried out according to a certain proportion, manual stirring or mechanical stirring is carried out, vacuum defoaming is carried out finally, the on-line time of the slow glue is also considered, the bad probability caused by human factors is increased in a series of processes, and the incoming material batch is checked by the film pasting process and the equipment is operated correctly.

(3) Carry out the electric light test behind the sticking film machine, if there is not good, can reprocess after demolising the membrane material, this technology easy operation just can not destroy whole board, can normal use after reprocess. The repair of the die pressing process can only be manually operated at present, the process is complex and difficult, the solidified glue needs to be removed, crystal and tin paste are removed, if the tin paste has residues and is repaired, chips are cut off obliquely, and finally the glue is dispensed and solidified, so that the color difference of the glue surface is easily caused, and the whole plate is scrapped.

(4) The film pasting process does not have the problems of glue shortage, small bubbles, incomplete curing and the like to influence functional indexes.

(5) The most important point is that the film pasting process does not need high temperature and high pressure of a mould pressing process, and the risk that the substrate is deformed under the high temperature and the high pressure is avoided. The molding temperature is generally above 150 ℃, while the film pasting process is only short-time curing at about 110 ℃.

(6) The deformation stress before and after curing of the packaging glue in the die pressing process is far greater than the film material curing stress of the film, and the film sticking process also reduces the deformation risk of the substrate.

Drawings

The invention is described in further detail below with reference to the accompanying drawings:

FIG. 1 is a first production flow chart of the film laminating process of the present invention;

FIG. 2 is a second flow chart of the film laminating process of the present invention;

FIG. 3 is an enlarged partial schematic view at A in FIG. 2;

FIG. 4 is an enlarged partial schematic view at B of FIG. 2;

FIG. 5 is an enlarged partial schematic view at C of FIG. 2;

FIG. 6 is an enlarged partial schematic view of FIG. 2 at D;

FIG. 7 is an enlarged partial schematic view at E in FIG. 2;

FIG. 8 is an enlarged partial schematic view at F of FIG. 2;

FIG. 9 is a detailed flow chart of rework;

FIG. 10 is a schematic structural view of a semi-cured film material;

wherein, 1 is a conveyor belt, 2 is a coiling roller, 3 is a PCB, 4 is a laminator, 5 is an electrical testing lighter, 6 is a vacuum defoaming machine, 7 is a repair machine, 8 is a curing dryer, 9 is a COB board, 10 is a component, 11 is an RGB chip, 12 is a semi-curing film material, 13 is a chip gap, 14 is a molded product, 15 is a finished product, and 16 is a defective point.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solution of the present invention is described in detail below with reference to the embodiments and the drawings, but the scope of protection is not limited thereto.

As shown in fig. 1 to 10, the present invention provides a COB packaging mode, in which a die-pressing packaging process in the prior art is replaced by a film-pasting process, and a specific packaging process flow is as follows:

the method comprises the following steps: PCB 3 design

And designing a corresponding chip carrier plate, namely a COB (chip on Board) 9 according to the terminal requirements.

Step two: face-driving paster

According to the design of the PCB 3, the components 10 such as capacitors, resistors, ICs, plug connectors and the like are pasted at corresponding positions by using solder paste.

Step three: reflow soldering

And setting corresponding temperature according to the characteristics of the solder paste, and baking and curing the solder paste added in the step two through reflow soldering.

Step four: chip bonding

And a special chip die bonder is adopted to fix the RGB chip 11 on the corresponding position of the inverted PCB 3 by matching with a proper clamp and a proper consumable material.

Step five: reflow soldering

And setting corresponding temperature according to the characteristics of the solder paste, and baking and curing the solder paste added in the fourth step by reflow soldering.

Step six: repair of

And point location identification is carried out on the PCB 3, and the identified bad points 16 are repaired by adopting special equipment, so that the yield of the process is ensured to be 100%.

The first step, the second step and the third step are the same as the conventional COB packaging process flow.

Step seven: jet printing caulking

Deep black ink is filled into the chip gaps 13 or pixel gaps through a high-precision jet printing machine, and the precision jet printing machine can realize micron-scale thickness control of the ink. The jet printing machine performs joint filling operation by using epoxy resin glue, and then enters a tunnel furnace for glue drying; the process is mainly used for making up the difference of the ink colors of the PCB 3, and simultaneously, the overall contrast of the module is improved, so that the contrast of 100000:1 can be easily realized.

Step eight: film pasting process

The most key point of the film pasting process is to select a proper semi-solidified film material 12, attach the semi-solidified film material in a vacuum film pasting mode and then solidify the semi-solidified film material. The semi-cured film material 12 is a matte black optical packaging film material, mainly made of a PET material, and comprises 8 layers (shown in figure 10), and a protective film, an anti-fingerprint protective layer, a nano anti-glare coating, a hardening ink layer, a PET substrate, a hardening layer, an optical glue layer and a protective layer are sequentially arranged from top to bottom. The material can be cured under the conditions of heating and pressurizing.

The film is generally attached in two sections, and heating and pressurizing are carried out in a first section of vacuum environment, so that semi-solidified film materials 12 are filled in chip gaps 13, and a formed product 14 which has no bubbles and can follow the shape is obtained; in the second stage, the laminate having the irregularities is heated again to flow and the surface is flattened by pressing.

The specific operation is as follows:

a conveyor belt 1 is provided, which conveyor belt 1 is driven by means of a take-up roller 2 to move the conveyor belt 1. The film sticking machine 4, the electric measurement lighting machine 5, the vacuum defoaming machine 6 and the curing dryer 8 are sequentially arranged along the conveying direction of the conveying belt 1, and the repairing machine 7 is arranged on one side of the electric measurement lighting machine 5. Two sections are arranged inside the vacuum defoaming machine 6 along the conveying direction of the conveyor belt 1.

Firstly, a conveying belt 1 conveys a workpiece, namely a PCB (printed Circuit Board) 3 into a laminator 4, and after the PCB 3 enters the laminator 4, the surface of the PCB 3 is covered with a layer of semi-cured film material 12.

Then, the PCB 3 output by the laminator 4 is transmitted into an electrical testing lighting machine 5 for lighting test. If the PCB is bad, the PCB 3 is transferred from the electrical testing and lighting machine 5 to a repairing machine 7, the semi-solidified film material 12 is removed by the repairing machine 7 (figure 8) to be repaired (figure 9), and the repaired PCB is transferred to the film sticking machine 4 again to be stuck with the film. If no defect exists, the PCB 3 is directly conveyed to the inside of the vacuum defoaming machine 6.

Specifically, as shown in fig. 9, after the semi-cured film material 12 is removed, when the defective spot 16 is repaired, the defective spot 16 is identified, then the laser decrystallization is performed on the defective spot 16, that is, the chip of the defective spot 16 is laser-removed, then the solder paste is removed, the pad is cleaned and leveled, the solder paste is re-spotted on the pad at the defective spot 16, then the die bonding is performed again, that is, the chip is laser-welded after the chip is selected, and finally the repaired cell board is obtained.

Then, the PCB 3 which is tested to be free of abnormity is lightened to carry out vacuum defoaming in the vacuum defoaming machine 6, the PCB 3 is attached in the vacuum defoaming machine 6 in a two-section mode, heating and pressurizing are carried out in a first-section vacuum environment, and the semi-cured film material 12 is filled in the chip gap 13, so that a formed product which is free of bubbles and can follow the shape is obtained; in the second stage, the laminate having irregularities is heated again to flow and the surface is flattened by pressing, thereby obtaining a finished product 15 after pressing the film material. Thus, the film is closely attached to the PCB 3 by heating the vacuum defoaming machine 6 (fig. 7).

And finally, conveying the PVB plate from the inside of the vacuum defoaming machine 6 to the inside of the curing dryer 8, performing UV curing, and drying to finish the plastic packaging process.

Step nine: cutting aging test repairing assembly

And cutting and assembling the box body on the edge of the PCB 3 after the film pasting process is finished, and setting corresponding current, voltage and scanning frequency to perform function test and aging on the module. If the defective spot 16 occurs again, the spot is repaired by using a dedicated device and then aged.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims

1. The utility model provides a COB's packaging mode which characterized in that: the method comprises the steps of replacing a die pressing packaging process in the existing COB packaging process with a film pasting process, carrying out jet printing joint filling on a PCB before the film pasting process is carried out, then covering a layer of semi-cured film material on the surface of the PCB through a film pasting machine, then carrying out lighting test on the PCB, if the PCB is bad, carrying out film pasting again after the PCB is repaired, if the PCB is not bad, carrying out vacuum deaeration on the PCB, heating to enable the film material to be tightly attached to the PCB, and finally curing and drying the PCB to complete the plastic packaging process.

2. The COB packaging mode of claim 1, wherein: the specific way of jet printing gap filling is that deep black ink is adopted to fill chip gaps or pixel gaps through a jet printing machine, then epoxy resin glue is used for gap filling, and then the epoxy resin glue enters a tunnel furnace for glue drying.

3. The COB packaging mode of claim 1, wherein: semi-solid preparation membrane material is mute black optical packaging membrane material, mainly is the PET material, and total 8 layers are from last to being protective film, preventing fingerprint protective layer, nanometer anti-dazzle coating, sclerosis processing black layer, PET substrate, sclerosis layer, optics glue film, protective layer down in proper order.

4. The COB packaging mode according to claim 1, wherein: be provided with a conveyer belt, the conveyer belt drives through batching cylinder, the coating machine has set gradually along the direction of transfer of conveyer belt, the electricity measures the lighter, the vacuum defoaming machine, the solidification drying-machine, one side that the electricity measured the lighter is provided with reprocesses the machine, bring conveying PCB board through the conveyer belt, carry out the pad pasting to the PCB board inside the coating machine, carry out bad some discernment to the PCB board in the electricity measures the lighter inside, reprocess the PCB board inside the reprocessor, carry out the vacuum deaeration to the PCB board inside the vacuum defoaming machine, solidify and dry the PCB board inside the solidification drying-machine.

5. The COB packaging mode of claim 1, wherein: when the PCB is repaired, the semi-cured film material on the PCB is removed, and the removed semi-cured film material is conveyed to the inside of the film sticking machine again for film sticking.

6. The COB packaging mode of claim 5, wherein: and removing the semi-cured film material, identifying bad points, performing laser crystal removal on the bad points, removing the solder paste, re-dispensing the solder paste, performing crystal solidification again, and finally obtaining a good product when the bad points are repaired.

7. The COB packaging mode according to claim 1, wherein: during the vacuum defoaming process, the semi-cured film material is attached in a two-stage mode, heating and pressurizing are carried out in a first-stage vacuum environment, so that the semi-cured film material is filled in gaps of the chips, and a formed product which is free of bubbles and can follow the shape is obtained; in the second stage, the laminate having the irregularities is heated again to flow and the surface is flattened by pressing.