CN1946268A - Through hole welding technology for mobile phone camera module image sensor - Google Patents

Abstract

This invention relates to a welding technology of electronic elements and devices, which first of all designs the welding plate welding image sensors to a mode of through holes then aligns tin balls of the sensor with the through holes on a flexible CB according to the requirement of products and the tin balls pass through the through hole, then welds it with a welding tool, finally cleans it and adheres reinforce plate on it.

Description

Mobile phone camera module image sensor via hole solder technology

Technical field

The present invention relates to a kind of solder technology of electronic devices and components, specifically a kind of technology that is applied to the mobile phone camera module image sensor welding.

Background technology

Because development of electronic technology, components and parts are towards powerful integrated chip development, and volume is also more and more littler.The powerful pin of integrated chip that makes of function is more and more, and this is also more and more higher to welding process requirement, and the imageing sensor in the cell-phone camera module is exactly the integrated chip of an encapsulation shown in the b1 among the figure.

Because the image sensor signal pin of cell-phone camera module is more, general signal pins is more than 22, and each signal pins all is the form of soldered ball, as the b2 among the figure.So cell-phone camera module factory nearly all is to use surface mount technology at present, the imageing sensor of finishing the cell-phone camera module is connected with the signal of flexible circuit board.Surface mount assembling processing procedure mainly comprises following key step: paste solder printing, assembly are put, reflow soldering.Its each overview of steps is as follows: paste solder printing (Stencil Printing): tin cream is the then material that surface sticking assembly and circuit board interconnect conducting, after at first steel plate being seen through etching or laser cutting, scraper (squeegee) by printing machine prints tin cream to the weld pad of circuit board through the perforate on the steel plate, so that enter next step.Assembly is put (Component Placement): it is that whole SMT (directly mounts the surface mount components and parts that assembly is put, be welded to the packaging technology on the printed circuit board surface assigned position) the main key technology and the focus of work of manufacturing process, its process uses high-accuracy automation to put equipment, via computer programming surface sticking assembly is seated in accurately on the weld pad of circuit board of tin cream out of the press.Because the design of surface sticking assembly is accurate day by day, the spacing of its pin also diminishes thereupon, and the technological layer of therefore the putting operation difficulty of taking second place also grows with each passing day.Reflow soldering (ReflowSoldering): reflow soldering is to put the circuit board of surface sticking assembly, go ahead of the rest preheating with the activation scaling powder through reflow ovens, promote its temperature to relevant temperature again and make the tin cream fusing, the weld pad of assembly pin and circuit board is connected, again through the cooling cooling, scolding tin is solidified, promptly finish engaging of surface sticking assembly and circuit board.

The defective of original technology: 1, solder joint is all at the back side of the imageing sensor b1 of cell-phone camera module, and is invisible during welding assembly, and aborning, wayward dry joint, short circuit, phenomenon such as open circuit take place to do normal inspection.2, solder joint is all at the back side of the imageing sensor b1 of cell-phone camera module, can not reprocess normally during the defective item found in process of production.3, all at the back side of the imageing sensor b1 of cell-phone camera module, the success rate of reprocessing is lower, has increased production cost for solder joint.4, the surface mount technology precision prescribed is higher, must use relevant professional equipment, and cost of investment is big.5, technological requirement is higher, the management and control complexity, and the employee is difficult for grasping.

Summary of the invention

The object of the present invention is to provide a kind of mobile phone camera module image sensor via hole solder technology, improve reliability of products heavy industry, ease for operation etc. on the one hand; Reduction equipment input and saving production cost is greatly enhanced productivity on the other hand.

According to technical scheme provided by the invention, mobile phone camera module image sensor via hole solder technology comprises:

A, perforate: at the corresponding via hole of soldered ball that is provided with on the pad of flexible circuit board on several and the imageing sensor, this via hole is a through hole, and the internal diameter of via hole is slightly larger than the external diameter of soldered ball, is advisable just in time to allow soldered ball to pass;

B, perforation:, and make soldered ball pass via hole on request with the soldered ball of imageing sensor and the via hole contraposition of flexible circuit board;

C, welding: soldered ball on the imageing sensor and flexible circuit board are welded together with soldering appliance;

D, cleaning: clean above-mentioned weld again, remove scaling powder, disturb in order to avoid residual scaling powder produces signal;

E, stickup: again stiffener is pasted on weld.

Advantage of the present invention is: after adopting method of operation of the present invention, the bad phenomenon that reduced short circuit in process of production, opens circuit has greatly improved the production output of cell-phone camera module, has accelerated operating efficiency, has reduced production cost.

Description of drawings

Fig. 1 is the schematic diagram of the pad perforate of flexible circuit board.

Fig. 2 is the schematic diagram of imageing sensor.

Contraposition schematic diagram when Fig. 3 welds for present technique.

Fig. 4 finishes the semi-finished product schematic diagram for the present technique welding.

Fig. 5 finishes the finished product schematic diagram for the present technique welding.

Embodiment

Among the figure, camera lens d1: the composition of camera lens is a lens arrangement, is made up of several lens, and plastic lens or glass lens are generally arranged; Base d2: cooperating with camera lens becomes the camera lens module; Imageing sensor b1: the device of image and electrical signal conversion; Flexible PCB a2: employing be complementary metal oxide semiconductors (CMOS), be used for signal transmission; Via hole a1: be one of important component part of multilayer circuit board, the expense of boring accounts for 30～40% of circuit board making sheet expense usually.In fact simple, each hole on the circuit board can be referred to as via hole; Soldered ball b2: the signal pins of imageing sensor b1, insert the via hole welding; Stiffener c1: be used to be pasted on weld, play a part reinforcement.

The welding procedure that imageing sensor in the cell-phone camera module is crossed cellular type comprises:

A, perforate: at the corresponding via hole a1 of soldered ball b2 that is provided with on the pad of flexible circuit board a2 on several and the imageing sensor b1, this via hole a1 is a through hole, and the internal diameter of via hole a1 is slightly larger than the external diameter of soldered ball b2, is advisable just in time to allow soldered ball b2 to pass;

B, perforation:, and make soldered ball b2 pass via hole a1 on request with the via hole a1 contraposition of soldered ball b2 and the flexible circuit board a2 of imageing sensor b1;

C, welding: soldered ball b2 on the imageing sensor b1 and flexible circuit board a2 are welded together with soldering appliance;

D, cleaning: clean above-mentioned weld again, remove scaling powder, disturb in order to avoid residual scaling powder produces signal;

E, stickup: again stiffener c1 is pasted on weld.

The mentality of designing of this programme derives from traditional perforation and inserts solder technology.The maximum difference of it and surface mount technology (SMT) is: surface mount technology (SMT) is the surface that components and parts is welded in wiring board; And present technique was a well format with the pad design of flexible circuit board, with the via hole back side welding by flexible circuit board of the soldered ball of imageing sensor.Via hole (via) is one of important component part of multilayer circuit board, and the expense of boring accounts for 30% to 40% of circuit board making sheet expense usually.In fact simple, each hole on the circuit board can be referred to as via hole.From using, via hole can be divided into two classes: the one, as being electrically connected of each interlayer; The 2nd, as the fixing or location of device.If from manufacturing process, these via holes generally are divided three classes again, i.e. blind hole (blind via), buried via hole (buried via) and through hole (throughvia).Blind hole is positioned at the top layer and the bottom surface of printed substrate, has certain depth, is used for being connected of top layer circuit and following internal layer circuit, and the degree of depth in hole is no more than certain ratio (aperture) usually.Buried via hole is meant the connecting hole that is positioned at the printed wire inner cord, and it can not extend to the surface of wiring board.Above-mentioned two class holes all are positioned at the internal layer of wiring board, utilize forming through holes technology to finish before the lamination, may also can overlappingly do several internal layers in the via hole forming process.The third is called through hole, and whole wiring board is passed in this hole, can be used for realizing intraconnection or as the installing and locating hole of element.

Claims (1)

1, mobile phone camera module image sensor via hole solder technology is characterized in that:

A, perforate: at the corresponding via hole of soldered ball (b2) (a1) that is provided with on the pad of flexible circuit board (a2) on several and the imageing sensor (b1), this via hole (a1) is a through hole, the internal diameter of via hole (a1) is slightly larger than the external diameter of soldered ball (b2), is advisable just in time to allow soldered ball (b2) to pass;

B, perforation:, and make soldered ball (b2) pass via hole (a1) on request with the soldered ball (b2) of imageing sensor (b1) and via hole (a1) contraposition of flexible circuit board (a2);

C, welding: soldered ball (b2) on the imageing sensor (b1) and flexible circuit board (a2) are welded together with soldering appliance;

D, cleaning: clean above-mentioned weld again, remove scaling powder, disturb in order to avoid residual scaling powder produces signal;

E, stickup: again stiffener (c1) is pasted on weld.

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