CN102082101A

CN102082101A - Packaging process method of photosensitive element

Info

Publication number: CN102082101A
Application number: CN2010102170009A
Authority: CN
Inventors: 陈吉; 谢禹钧; 刘峰; 蒋应田
Original assignee: Liaoning Shihua University
Current assignee: Liaoning Shihua University
Priority date: 2010-07-02
Filing date: 2010-07-02
Publication date: 2011-06-01
Anticipated expiration: 2030-07-02
Also published as: CN102082101B

Abstract

The invention relates to a packaging process of a photosensitive element, in particular to a packaging process method of a photosensitive element, which comprises the steps of: directly mounting a photosensitive bare chip on a PCB (Printed Circuit Board), then adding a packaging plate and finally adhering an MASK. The method in the invention has the advantages of lowering the packaging difficulty, reducing the process procedures, realizing that the packaging structure of the photosensitive element is simplified, saving cost, shortening the production time, improving the production efficiency, increasing the size accuracy of the photosensitive element to a certain degree, meeting the requirement for the GAP accuracy, and being remarkably superior to the traditional packaging method of the photosensitive element. The method can be popularized to other packaging procedures related to the chip elements.

Description

A kind of packaging process of light-sensitive device

One, technical field

The present invention relates to the method for packing of the packaging technology of chip device, particularly light-sensitive device.

Two, background technology

The light-sensitive device kind is varied, is widely used in the every field of national economy such as civilian, aviation, national defence.The operation principle of normal optical sensing device is: light-sensitive device is encapsulated on the printed circuit board (PCB) (PCB), led light source sees through code-disc grating irradiates light sensing device, and the photoetching on light-sensitive device surface is covered worn-out layer (MASK) and is engaged in the surperficial grating Moire fringe that forms of receiver with moving grating.Wherein photoreceptor photomask surface masking layer (MASK) is to the distance of code-disc grating, the sensitiveness of just so-called gap parameter (GAP) appreciable impact rotation code-disc Moire fringe projection on light-sensitive device is an important parameter of light-sensitive device production technology and quality control.The packaging technology of light-sensitive device should guarantee the precision of GAP distance, guarantees parallel between code-disc and the light-sensitive device surface again, and it is the smaller the better to require to mount between PCB, light-sensitive device receiver, the MASK error.

The light-sensitive device method for packing is that packaged chip is welded on the PCB surface by surface mounting technology (SMT) with the encapsulation in advance of photosensitive bare chip mostly at present.Be about to be welded on the PCB surface by the SMT mode again after photosensitive bare chip encapsulates with encapsulation lower plate, encapsulation upper plate and encapsulation cover plate.The structure of encapsulation back light-sensitive device is followed successively by:

1. solder thickness a

2. encapsulate plate thickness b down

3. encapsulate upper and lower plates intermediate gelatine layer thickness c

4. encapsulate the upper plate thickness d

5. encapsulate the middle bondline thickness e of upper plate and encapsulation cover plate

6. encapsulation cover plate f

7. the bondline thickness g in the middle of encapsulation cover plate and the MASK

8. MASK thickness h

Then final receiving device thickness K1=a+b+c+d+e+f+g+h

In practical set technology, all by accumulative total, cumulative errors are the error of each thickness: Δ K1.

Have eight layers of structure by the light-sensitive device after this technology encapsulation, the encapsulation precision of each layer structure is strict, and the technology controlling and process very complicated is wasted a large amount of time and materials; Each layer glue and package board technology all produce error simultaneously, and cumulative errors are bigger, finally influence the control precision of GAP.The existing defective of current light-sensitive device method for packing directly influences the quality of light-sensitive device.

Three, summary of the invention

The packaging process that the purpose of this invention is to provide a kind of light-sensitive device adopts this process, can reduce light-sensitive device encapsulation back error, reduces technological process and saves material, and the precision of raising GAP is to reach the requirement of instrument to light-sensitive device.

The inventive method will not mount on the PCB by SMT after the encapsulation by the electronics bare chip in advance again, but photosensitive bare chip is directly mounted on the PCB, adds package board then, pastes MASK again.This technology has reduced encapsulation difficulty, has reduced technological process, has realized that the light-sensitive device encapsulating structure simplifies most.Light-sensitive device structure after the encapsulation is followed successively by:

1. PCB and package board intermediate gelatine layer thickness a

2. package board thickness b

3. package board and MASK intermediate gelatine layer thickness c

4. MASK thickness d

Encapsulating concrete processing step is: on the PCB that at first photosensitive bare chip sticked with glue, package board is sticked with glue on the PCB around the photosensitive bare chip again, paste MASK at last on package board.The final receiving device thickness K2=a+b+c+d in its encapsulation back

In practical set technology, all by accumulative total, cumulative errors are the error of each thickness: Δ K2.

In sum, the cumulative errors of the inventive method are far smaller than the cumulative errors of conventional method, i.e. Δ K2＜Δ K1.Traditional handicraft is difficult to satisfy the high requirement of GAP to precision, and technological process of the present invention is simple, and encapsulation back light-sensitive device only has four-layer structure, and cumulative errors are less, have obvious superiority, can satisfy the degree of precision requirement of GAP size.

The direct mounting method of photosensitive bare chip of the present invention has been simplified light-sensitive device packaging technology flow process significantly, has reduced process complexity, saves cost, has reduced the production time, enhances productivity; And improved the dimensional accuracy of light-sensitive device to a certain extent, satisfied the requirement of GAP precision, obviously be better than traditional light-sensitive device encapsulation scheme.The method can be generalized to other encapsulation processs that relates to chip device.

Four, description of drawings

Fig. 1 is a light-sensitive device operation principle schematic diagram;

Fig. 2 is traditional light-sensitive device packaging technology schematic diagram;

Fig. 3 is the structural representation after traditional light-sensitive device encapsulation;

Fig. 4 is a light-sensitive device packaging technology schematic diagram of the present invention;

The structural representation of Fig. 5 after for light-sensitive device of the present invention encapsulation.

Five, embodiment

The operation principle of light-sensitive device is that photoreceiver 9 is encapsulated on the pcb board 1, the surface of photoreceiver 9 has photoetching to cover worn-out layer MASK6, the code-disc grating 8 of rotation is set in the MASK6 front, the led light source 7 in code-disc grating 8 outsides sees through code-disc grating 8 irradiation MASK6, and the code-disc grating 8 of MASK6 and rotation is engaged in photoreceiver 9 surfaces and forms the grating Moire fringe.

Tradition light-sensitive device packaging technology is that photosensitive bare chip 2 usefulness encapsulation lower plate 12 and encapsulation upper plate 14 are packaged together by viscose glue 13, encapsulation lower plate 12 is solid flat board, saturating empty in the middle of the encapsulation upper plate 14, again the saturating empty encapsulation cover plate 16 usefulness glue 15 in centre are sticked on the encapsulation upper plate 14, again packaged chip 10 usefulness scolding tin 11 are welded on the PCB1, on encapsulation cover plate 16, use glue 5 bonding MASK6 at last.

Concrete encapsulation step of the present invention is: on the PCB 1 that at first photosensitive bare chip 2 sticked with glue, package board 3 usefulness glue 4 are sticked on photosensitive bare chip 2 PCB1 all around again, paste MASK6 with glue 5 at last on package board 3.Said package board 3 is the saturating empty whole plates in a centre, saturating vacancy, the centre of package board 3 is greater than the area of photosensitive bare chip 2, the thickness of package board 2 is greater than the thickness of photosensitive bare chip 2, photosensitive bare chip 2 packed plates 3 are trapped among its saturating vacancy when encapsulation, MASK6 sticks on above the package board 3, and photosensitive bare chip 2 is covered.

The auxiliary lead circuit that adapts with photosensitive bare chip 2 is arranged on PCB1, and this auxiliary lead circuit directly is printed on the circuit board PCB1 upper surface, need not extra encapsulating lead.

SMT among the present invention (surface mount technology surface mounting technology) is a kind of circuit assembly technology, originate from the eighties in 20th century, be with electronic component, be installed on the surface-mounted integrated circuit (Print Circuit Board) as resistance, electric capacity, transistor, integrated circuit or the like, and form electric connection by soldering.

GAP refer in particular to encoder make in distance between code-disc and the anti-dazzling screen.

MASK is that worn-out layer (also claim anti-dazzling screen or be quiet grating) is covered in the photoetching on light-sensitive device surface, refers in particular to during encoder makes, and is engaged in the thin slice that the receiver surface forms the grating Moire fringe (thin slice of being made up of printing opacity and light tight striped) with moving grating.

Claims

1. the packaging process of a light-sensitive device, it is characterized in that: it is that photosensitive bare chip (2) is directly mounted on the PCB (1), adds package board (3), pastes MASK (6).

2. the packaging process of light-sensitive device according to claim 1, it is characterized in that: concrete encapsulation step is: on the PCB (1) that at first photosensitive bare chip (2) sticked with glue, again package board (3) is sticked with glue on photosensitive bare chip (2) PCB (1) all around, on package board (3), paste MASK (6) at last.

3. the packaging process of light-sensitive device according to claim 1 and 2, it is characterized in that: said package board (3) is the saturating empty whole plate in a centre, the saturating vacancy, centre of package board (3) is greater than the area of photosensitive bare chip (2), the thickness of package board (3) is greater than the thickness of photosensitive bare chip (2), the packed plate of photosensitive bare chip (2) (3) is trapped among its saturating vacancy when encapsulation, MASK (6) sticks on above the package board (3), and photosensitive bare chip (2) is covered.

4. the packaging process of light-sensitive device according to claim 1 and 2 is characterized in that: have the auxiliary lead circuit that adapts with photosensitive bare chip (2), this auxiliary lead circuit directly to be printed on circuit board PCB (1) upper surface on PCB (1).