CN102148215B

CN102148215B - Interconnection structure for improving reliability of soldering spot of soft soldering of CCGA (Ceramic Column Grid Array) device and implementation method

Info

Publication number: CN102148215B
Application number: CN2011100239413A
Authority: CN
Inventors: 赵智力; 孙凤莲
Original assignee: Harbin University of Science and Technology
Current assignee: Harbin University of Science and Technology
Priority date: 2011-01-21
Filing date: 2011-01-21
Publication date: 2012-06-06
Anticipated expiration: 2031-01-21
Also published as: CN102148215A

Abstract

The invention provides an interconnection structure for improving the reliability of a soldering spot of soft soldering of a CCGA (Ceramic Column Grid Array) device and an implementation method, belonging to the technical field of microelectronic packaging. The invention aims to solve the problems that the reliability of the conventional area array package device is generally lower than that of a peripheral leaded package device and a high-frequency and high-power large-area area array package device has low reliability and short service life. A Cu column in the interconnection structure consists of a cylinder and two end heads which are integrally formed; each end head is in the shape of a revolved body in which a straight line or cambered line is used as a bus; the cylinder is positioned between the two end heads which are arranged back to back, and the cylinder and the two end heads are coaxial; the cylinder is in smooth transition with the end heads; and the height of a soldering round corner is less than that of the end heads. The method comprises the following steps of: soldering one end of the Cu column on a metal film bonding pad at one side of a chip carrier substrate by using high-melting-point solder paste; and then soldering the other end of the Cu column on the metal film bonding pad at one side of a printed circuit board by using low-melting-point solder paste. The interconnection structure has high reliability and long service life and can be used for packaging a large chip.

Description

Improve the interconnection structure and the implementation method of CCGA device solder welding spot reliability

Technical field

The present invention relates to interconnection structure and its implementation of a kind of CCGA device, relate to the improvement of CCGA device inside interconnection structure, belong to the microelectronic packaging technology field.

Background technology

Unleaded, microminiaturized, multi-functional and high reliability is the striving direction of electronic product manufacturing in recent years.Compare with four limit pin package forms; I/O (I/O) quantity of the packing forms of face array arrangement solder joint on unit are is geometric progression to be increased; Promoted Development of HDI Package Technology, made electronic product constantly stride forward to microminiaturized, multi-functional target.Yet; The target of high reliability does not but obtain synchronized development; The accelerated life test data show; Compare with the face array package device of this no pin of PBGA (Plastic Ball Grid Array), the absorption of pin counter stress makes the fatigue life of PLCC (Plastic Lead Chip Carrier) and QFP (Quad Flat Package) four limit pin package device solder joints higher, is 2-3 times of PBGA.

Because the thermal fatigue life of face array package device increases with package dimension and reduces; Large chip encapsulation for high-frequency, high power, high I/O; Usually need to adopt CGA (Column Grid Array) packing forms to substitute BGA (Ball GridArray) encapsulation, improve the heat-sinking capability of device and effectively alleviate the stress that TCE (Thermal Coefficient ofExpansion) difference causes between ceramic chip carrier substrate and the resin substrate by highly higher solder post.However, low approximately 1000 circulations of average life span reduced size chip CBGA (the CeramicBall Grid Array) device of large chip CCGA (Ceramic Column Grid Array) device, in addition poorer.

In addition, the high lead solder pole interconnection in the CCGA device does not meet the requirement of unleaded encapsulation yet, and the application of CGA encapsulation is placed in an awkward position.IBM Corporation once proposed to adopt the copper post, and (" copper post " described here was the copper coin post in 2005; The cross-sectional area of copper coin post is constant, referring to Fig. 4) replace high lead solder post, because pliable and tough copper post is easy to deflection deformation during the thermal cycle; The inner stress of interconnection can be discharged by part; Therefore, the CCGA device of copper pole interconnection increases than the thermal fatigue life of the CCGA device of solder pole interconnection, but only limits to the suitable level with small size chip CBGA.

In sum, present present condition for application is, the thermal cycle life of face array package device generally is lower than peripheral pin package device, the synchronized development of high reliability that can not realize encapsulating and high density, microminiaturization, multi-functional target.Therefore; Be necessary to take effective ways and measure to improve the reliability of face array package device; With the reliability requirement that the large chip that satisfies following high-frequency, high power, high I/O encapsulates, the manufacturing for Aero-Space and military electronic product simultaneously provides the more encapsulation of high reliability.

Summary of the invention

The present invention is lower than peripheral pin package device and high-frequency, high-power large chip packaging reliability is low, useful life is short problem in order to solve existing face array package device reliability.The improvement of desire of the present invention through CCGA device inside interconnection structure significantly reduces the inner stress of soldering fillet, interconnection structure and its implementation that purpose provides is that a kind of CCGA of making device reliability significantly improves, can be used for the large chip encapsulation.

The target that the present invention desires to reach is:

1), the thermal cycle life of face array package device is suitable with peripheral pin package device, and is even higher;

2), the outer ability of carrying of face array package device opposing machinery significantly improves.

Design concept of the present invention:

Be the welding column interconnection of face array arrangement in the traditional C CGA device; Normally adopt low-melting eutectic solder that the two ends of the dystectic high lead solder post in centre position are soldered to respectively on chip carrier substrate pad and the printed circuit board pads, the composite soldering solder joint of formation obviously and do not meet the unleaded requirement of electronic product.Therefore easily simultaneously, the high lead solder ductility of traditional C CGA is poor, can not discharge internal stress by means of the distortion of solder post in the military service process, forms bigger stress at the interface location of two kinds of solders and concentrates and ftracture.And copper post CCGA interconnection; Promptly adopt low-melting eutectic solder that the two ends of the copper coin post in centre position are soldered to the interconnection on chip carrier substrate pad and the printed circuit board pads respectively; Though can come the release portion internal stress through distortion; But solder/Cu post interface soldering fillet tip remains the ess-strain concentrated position (the interface A portion like Fig. 4 is the ess-strain concentrated position) of whole interconnection structure, and the soldering fillet that promptly performance is weak need be born the peak strain of whole interconnection structure.

Under load-up condition one stable condition, the reliability of device solder joint depends on the performance that connects material and linkage interface on the one hand, and is closely related with encapsulating structure or solder joint geometry on the other hand.Therefore; Under the quite ripe condition of the exploitation of present lead-free brazing; The improvement of interconnection structure can be followed two principles; The one, reduce the stress concentration degree that interconnects under the different loads form; Two be based on electronic device the weak area inefficacy that is usually located at solder welding spot interface or inside, 70% above electronic product be because the fact that the solder welding spot cracking causes, in the time of the inner stress raisers degree of control solder welding spot, make the performance better material replace the weak soldering fillet of performance to bear the peak stress and the peak strain of interconnection through design as far as possible.

Technical scheme of the present invention is:

Interconnection structure according to the invention comprises Cu post and the soldering fillet that is positioned at Cu post two ends; Said interconnection structure is used to realize metal film pad and the machinery between the metal film pad on the printed circuit board (PCB) on chip or the chip carrier substrate and be electrically connected; Said Cu post is made up of the cylinder of processing one and two terminations; It is the rotational-like of bus that each termination is with straight line or circular arc line; Cylinder be back between two terminations that are provided with and the three coaxial, seamlessly transit between cylinder and the termination; The height of soldering fillet is less than the height of termination.

The implementation method of the interconnection knot of above-mentioned raising CCGA device solder welding spot reliability realizes according to following steps:

Step 1, preparation Cu post: to burning ball (only the termination that ball forms is burnt at the two ends of copper coin post silk and be shaped as segment shape) or the two ends of copper coin post silk are burnt the mould that utilizes given shape behind the ball again and burns Cu ball is implemented extruding (mould that utilizes given shape after the two ends of copper coin post silk are burnt ball again is shaped as truncated cone-shaped, billiard table shape or other shape in an end of the silk termination that formation is pushed in enforcement to burning Cu ball) in the two ends of copper coin post silk, to form the shape of above-mentioned termination at an end of silk;

Step 2, elder generation are printed onto the solder(ing) paste of an amount of high-melting point lead-free solder SnAg18 on a plurality of metal film pads that are arranged in array of chip carrier substrate one side; Also vertically be placed into an end centering of a plurality of Cu posts on corresponding a plurality of metal film pads; One end of a plurality of Cu posts once is soldered on a plurality of metal film pads of chip carrier substrate one side, and brazing temperature is controlled at above 20～40 ℃ of solder liquidus temperature; The amount of solder paste of control printing makes the height of the soldering fillet of formation be no more than the height of the termination of Cu post;

Step 3, solder(ing) paste that then will an amount of more low-melting lead-free brazing Sn3.0Ag0.5Cu are printed onto on a plurality of metal film pads that are arranged in array of printed circuit board (PCB) one side; Also vertically be placed into the other end centering of a plurality of Cu posts on a plurality of metal film pads of corresponding printed circuit board (PCB) one side; The other end of a plurality of Cu posts once is soldered on a plurality of metal film pads of printed circuit board (PCB) one side, and brazing temperature is controlled at above 20～40 ℃ of solder liquidus temperature; The amount of solder paste of control printing makes the height of soldering fillet be no more than the height of the termination of Cu post;

Step 4, accomplish above step, can obtain the CCGA interconnection structure that the solder welding spot reliability significantly improves.

The present invention has following useful technique effect:

Innovative point of the present invention is through copper coin column end (referring to the 1-2 of Fig. 1 a, Fig. 2 a and Fig. 3 a) geometry design; Make the peak strain of interconnection structure change the end (referring to the B portion of Fig. 1 b, Fig. 2 b and Fig. 3 b) that is positioned at the copper coin post into by being arranged in soldering fillet most advanced and sophisticated (referring to the A portion of Fig. 4, the interface of solder and Cu post).In other words; During the thermal cycle or under the effect of mechanical external force load; The transition position (referring to the B portion of Fig. 1 b, Fig. 2 b and Fig. 3 b) of the cylinder 1-1 of Cu post 1 of the present invention and two end portion 1-2 (Cu matter round platform, Cu matter billiard table or Cu matter segment or other) has been born the peak stress and the peak strain of interconnection structure; The ess-strain at soldering fillet 2 (referring to Fig. 1, Fig. 2 and Fig. 3) inside and interface is significantly reduced; The soldering fillet 2 that performance is weak is protected, and welding spot reliability can be significantly improved.

The present invention is applicable to interconnection and the interconnection of large chip face array package device of the face array package device of high reliability request.The present invention significantly improves the solder welding spot reliability that bears thermal cycle load and the outer CCGA device that carries of machinery.The present invention makes the reliability of face array package device suitable with peripheral pin package device, has promoted the high reliability and the synchronous coordination development unleaded, microminiaturized, multi-functional target of face array package.The interconnection structure and the implementation method of raising of the present invention CCGA device solder welding spot reliability are applicable to the electric and mechanically interconnected of chip that difference of thermal expansion coefficients is bigger or the face array arrangement between chip carrier substrate and the printed circuit board (PCB).

Concrete beneficial effect of the present invention shows the following aspects:

(1) adopt two ends be back to the high lead solder pole interconnection of interconnection replaced C CGA device of the funnelform Cu pole interconnection of truncated cone-shaped, billiard table shape or dumb-bell shape Cu post, can realize the unleaded encapsulation of CCGA device.

(2) adopt two ends be back to the high lead solder pole interconnection of interconnection replaced C CGA device of the funnelform Cu pole interconnection of truncated cone-shaped, billiard table shape or dumb-bell shape Cu post; The Cu post that pliability is good can deform during the thermal cycle or under the effect of mechanical external force load; But release portion internal stress; Can reduce the stress concentration degree of interconnection, the higher lead solder pole interconnection of reliability improves.

(3) adopt two ends be back to the Cu cylinder interconnection of interconnection replaced C CGA device of the funnelform Cu pole interconnection of truncated cone-shaped, billiard table shape or dumb-bell shape Cu post; The round platform of Cu matter, billiard table or dumbbell ball portion force solder wetting and form the interconnection contour shape of rounding off between its periphery and pad; The stress concentration degree of interconnection structure reduces, and can further improve welding spot reliability.

(4) adopt two ends be back to the funnelform Cu pole interconnection of truncated cone-shaped, billiard table shape or the Cu pole interconnection of dumb-bell shape Cu pole interconnection replaced C CGA device; During the thermal cycle or copper round platform, billiard table or dumbbell ball-joint carried on a shoulder pole interconnection structure under the effect of mechanical external force load peak stress and peak strain; The ess-strain of soldering fillet significantly reduces; The soldering fillet that performance is weak is protected, and welding spot reliability can be significantly improved.

(5) adopt two ends be back to the funnelform Cu pole interconnection of truncated cone-shaped, billiard table shape or the Cu pole interconnection of dumb-bell shape Cu pole interconnection replaced C CGA device; Changed during Cu post/solder interface direction and the thermal cycle or the following angular relationship that interconnects between the principal direction of stress of mechanical external force load effect; Be unfavorable for the germinating of crackle and further expand that welding spot reliability can be significantly improved.

(6) adopt two ends be back to the funnelform Cu pole interconnection of truncated cone-shaped, billiard table shape or the welding column interconnection of dumb-bell shape Cu pole interconnection replaced C CGA device; The solder welding spot reliability that bears thermal cycle load and the outer CCGA device that carries of machinery is significantly improved; Make the reliability of face array package device suitable with peripheral pin package device; Promoted the high reliability and the synchronous coordination development unleaded, microminiaturized, multi-functional target of face array package, engineering significance is comparatively desirable.

Description of drawings

Fig. 1 a is the vertical section sketch map of the interconnection structure that is formed by 1 soldering of Cu post of corresponding embodiment 1, wherein, Cu post 1 be two ends back to the truncated cone-shaped funnel-form; Fig. 1 b is that amplify the part of Fig. 1 a, is near soldering solder joint shape and the geometric parameter sketch map the Cu post 1 one end terminations; Among the figure, 1-1 is the barrel portion of Cu post 1, and 1-2 is the Cu matter Rotary-table part at Cu post 1 two ends; 2 are the soldering fillet; 3 is chip or chip carrier substrate, and 4 is printed circuit board (PCB), and 5 is the metal film pad on chip or the chip carrier substrate, the metal film pad on the printed circuit board (PCB).

Fig. 2 a is the vertical section sketch map of the interconnection structure that is formed by 1 soldering of Cu post of corresponding embodiment 2, wherein, Cu post 1 be two ends back to billiard table shape funnel-form; Fig. 2 b is that amplify the part of Fig. 2 a, is near soldering solder joint shape and the geometric parameter sketch map the Cu post 1 one end terminations; Among the figure, 1-1 is the barrel portion of Cu post 1, and 1-2 is the Cu matter billiard table part at Cu post 1 two ends; 2 are the soldering fillet; 3 is chip or chip carrier substrate, and 4 is printed circuit board (PCB), and 5 is the metal film pad on chip or the chip carrier substrate, the metal film pad on the printed circuit board (PCB).

Fig. 3 a is the vertical section sketch map of the interconnection structure that is formed by 1 soldering of Cu post of corresponding embodiment 3, and wherein, the termination, two ends of Cu post 1 is segment shape, similar dumbbell shape; Fig. 3 b is that amplify the part of Fig. 3 a, is near soldering solder joint shape and the geometric parameter sketch map the Cu post 1 one end terminations; Among the figure, 1-1 is the barrel portion of Cu post 1, and 1-2 is the Cu matter segment part at Cu post 1 two ends; 2 are the soldering fillet; 3 is chip or chip carrier substrate, and 4 is printed circuit board (PCB), and 5 is the metal film pad on chip or the chip carrier substrate, the metal film pad on the printed circuit board (PCB).

Fig. 4 is the vertical section sketch map (mentioning in the background technology) of the CCGA interconnection structure that formed by the soldering of copper coin post in the prior art.

Embodiment

Embodiment one: shown in Fig. 1 a, Fig. 1 b, Fig. 2 a, Fig. 2 b, Fig. 3 a and Fig. 3 b; The interconnection structure of the described raising of this execution mode CCGA device solder welding spot reliability comprises Cu post 1 and the soldering fillet 2 that is positioned at Cu post 1 two ends; Said interconnection structure is used to realize metal film pad 5 and the machinery between the metal film pad 5 on the printed circuit board (PCB) 4 on chip or the chip carrier substrate 3 and be electrically connected; Said Cu post 1 is made up of the cylinder 1-1 that processes one and two termination 1-2; It is the rotational-like of bus that each termination 1-2 is with straight line or circular arc line; Cylinder 1-1 be back between two termination 1-2 that are provided with and the three coaxial, seamlessly transit between cylinder 1-1 and the termination 1-2; The height h of soldering fillet 2 is less than the height l of termination 1-2 ₁

Embodiment two: shown in Fig. 1 a and Fig. 1 b, each termination 1-2's is shaped as truncated cone-shaped in this execution mode; Each processes one with the upper bottom surface (small end end face) of a termination 1-2 two ends of cylinder 1-1.Other composition and annexation are identical with embodiment one.

Embodiment three: shown in Fig. 2 a and Fig. 2 b, each termination 1-2's is shaped as the billiard table shape that the bottom surface radius is the radius of a ball (billiard table shape is meant that spheroid is cut the part that is clipped in the middle of two planes by two parallel planes) in this execution mode; Each processes one with the upper bottom surface (small end end face) of a termination 1-2 two ends of cylinder 1-1.Other composition and annexation are identical with embodiment one.

Embodiment four: shown in Fig. 3 a and Fig. 3 b, each termination 1-2's is shaped as height greater than the segment shape of the radius of a ball in this execution mode; The two ends of cylinder 1-1 each with a termination 1-2 on face directly and process one.Other composition and annexation are identical with embodiment one.

Embodiment five: shown in Fig. 1 a and Fig. 1 b; In this execution mode the diameter d of cylinder 1-1 more than or equal to 0.20mm and smaller or equal to the diameter D of metal film pad 5 1/3 (0.20≤d≤D/3), the height l of Cu post 1 is more than or equal to 1.50mm and smaller or equal to 3.00mm (150≤l≤3.00); Bottom surface (end face greatly) diameter d of the truncated cone-shaped termination 1-2 of Cu post 1 ₁Be 1.5 times to 2 times of cylinder 1-1 diameter d, the height l of truncated cone-shaped termination 1-2 ₁More than or equal to the diameter d of cylinder 1-1 1/2nd and smaller or equal to truncated cone-shaped termination 1-2 bottom surface (end face greatly) diameter d ₁1/2nd (d/2≤l ₁≤d ₁/ 2).Other composition and annexation are identical with embodiment two.

Embodiment six: shown in Fig. 2 a and Fig. 2 b; In this execution mode the diameter d of cylinder 1-1 more than or equal to 0.20mm and smaller or equal to metal film pad 5 diameter D 1/3 (0.20≤d≤D/3), the height l of Cu post 1 is more than or equal to 1.50mm and smaller or equal to 3.00mm (150≤l≤3.00); The bottom surface diameter d of the billiard table shape termination 1-2 of Cu post 1 ₁Be 1.5 times to 2 times of cylinder 1-1 diameter d, the height l of billiard table shape termination 1-2 ₁Be 0.75 times to 1 times of cylinder 1-1 diameter d.Other composition and annexation are identical with embodiment three.

Embodiment seven: shown in Fig. 3 a and Fig. 3 b; In this execution mode the diameter d of cylinder 1-1 more than or equal to 0.20mm and smaller or equal to metal film pad 5 diameter D 2/5 (0.20≤d≤2D/5), the height l of Cu post 1 is more than or equal to 2.00mm and smaller or equal to 3.50mm (2.00≤l≤3.50); The bulb diameter d of segment shape termination 1-2 ₁Be 1.5 times to 2 times of cylinder 1-1 diameter d, the height l of segment shape termination 1-2 ₁Be 1.5 times to 2 times of cylinder 1-1 diameter d.Other composition and annexation are identical with embodiment four.

Embodiment eight: shown in Fig. 1 a, Fig. 1 b, Fig. 2 a, Fig. 2 b, Fig. 3 a and Fig. 3 b, the implementation method of the interconnection knot of the described raising of this execution mode CCGA device solder welding spot reliability realizes according to following steps:

Step 1, preparation Cu post 1: to burning ball (only the termination that ball forms is burnt at the two ends of copper coin post silk and be shaped as segment shape) or the two ends of copper coin post silk are burnt the mould that utilizes given shape behind the ball again and burns Cu ball is implemented extruding (mould that utilizes given shape after the two ends of copper coin post silk are burnt ball again is shaped as truncated cone-shaped, billiard table shape or other shape in an end of the silk termination that formation is pushed in enforcement to burns Cu ball) in the two ends of copper coin post silk, with the shape of formation embodiment one described termination 1-2 at an end of silk;

Step 2, elder generation are printed onto the solder(ing) paste of an amount of high-melting point lead-free solder SnAg18 on a plurality of metal film pads 5 that are arranged in array of chip carrier substrate 3 one sides; Also vertically be placed into an end centering of a plurality of Cu posts 1 on corresponding a plurality of metal film pads 5; One end of a plurality of Cu posts 1 once is soldered on a plurality of metal film pads 5 of chip carrier substrate 3 one sides, and brazing temperature is controlled at above 20～40 ℃ of solder liquidus temperature; The amount of solder paste of control printing makes the height h of the soldering fillet 2 of formation be no more than the height l of the termination 1-2 of Cu post 1 ₁

Step 3, solder(ing) paste that then will an amount of more low-melting lead-free brazing Sn3.0Ag0.5Cu are printed onto on a plurality of metal film pads 5 that are arranged in array of printed circuit board (PCB) 4 one sides; Also vertically be placed into the other end centering of a plurality of Cu posts 1 on a plurality of metal film pads 5 of corresponding printed circuit board (PCB) 4 one sides; The other end of a plurality of Cu posts 1 once is soldered on a plurality of metal film pads 5 of printed circuit board (PCB) 4 one sides, and brazing temperature is controlled at above 20～40 ℃ of solder liquidus temperature; The amount of solder paste of control printing makes the height h of soldering fillet 2 be no more than the height l of the termination 1-2 of Cu post 1 ₁

Above content is to combine concrete preferred implementation to further specify what the present invention did, can not assert that practical implementation of the present invention is confined to these explanations.For the those of ordinary skill of technical field under this, under the prerequisite that does not break away from the present invention's design, can also make some simple deduction or replace, all should be regarded as belonging to the definite scope of patent protection of claims that the present invention submits to.

Embodiment:

Embodiment 1: referring to Fig. 1 a～1b; The interconnection structure of described raising CCGA device solder welding spot reliability; Form by the Cu post 1 in centre position and the soldering fillet 2 at two ends; Promptly adopt the two ends of the Cu post 1 in a plurality of centre positions that lead-free brazing will be arranged in array to be soldered to respectively to form on the metal film pad 5 on metal film pad 5 and the printed circuit board (PCB) 4 on the corresponding chip carrier substrate 3, wherein the two ends of Cu post 1 are processed to truncated cone-shaped; And in order to keep the encapsulation order; The soldering fillet 2 at two ends approximately differs two kinds of lead-free brazing solderings of 100 ℃ by fusing point respectively and forms; Wherein, what printed circuit board (PCB) 4 one sides adopted is the general lead-free brazing of low-melting surface-assembled, and the concrete implementation procedure of described interconnection structure is:

Step 1, confirm draw ratio (ratio of the diameter d of the height l of Cu post 1 and the Cu cylinder 1-1) scope of Cu post 1 according to electrical property: according to the diameter and the height of high lead solder post in the traditional C CGA device that is replaced; By formula the scope of draw ratio that electrical property is superior to the Cu post 1 of high lead solder post is calculated in (1)

Wherein: l is the post height; D is a column diameter, i.e. the diameter of the cylinder 1-1 of Cu post 1; ρ is a resistivity;

Step 2, confirm diameter d and the height l scope of Cu post 1 of the cylinder 1-1 of Cu post 1 based on rigidity requirement: have enough rigidity under the effect of structure gravity and mechanical external force load in thermal deformation load on it for guaranteeing Cu post 1; The diameter d of Cu cylinder 1-1 should be not less than 0.20mm, and the height l of Cu post 1 is not more than 3mm;

Step 3, confirm the scope of Cu cylinder 1-1 diameter d based on packaging density: under the constant situation of packaging density; Be under the constant situation of upper and lower base plate metal film pad diameter D and solder pad space length; For the good wet that guarantees soldering fillet 2 is connected with soldering, Cu cylinder 1-1 diameter d maximum is no more than 1/3 of pad diameter D;

Step 4, select and the diameter d of definite Cu cylinder 1-1 and the height l of Cu post 1 according to step 1, two, three (simultaneously satisfy);

Step 5, processing meet the Cu post 1 of step 4 geomery requirement, during 1 machine-shaping of Cu post, control the base diameter d of the Cu matter round platform part at its two ends ₁Be about 1.5 times to 2 times of cylinder 1-1 diameter d, the height l of control truncated cone-shaped termination 1-2 ₁More than or equal to the diameter d of cylinder 1-1 1/2nd and smaller or equal to round platform bottom surface (end face greatly) diameter d ₁1/2nd;

Step 6, elder generation adopt dystectic lead-free brazing; Like SnAg18; All ends that are the Cu post 1 of face array arrangement are soldered on the metal film pad 5 of chip carrier substrate 3 one sides; And then adopt the general lead-free brazing of more low-melting surface-assembled, like Sn3.0Ag0.5Cu, all other ends that are the Cu post 1 of face array arrangement are soldered on the metal film pad 5 of printed circuit board (PCB) 4 one sides.The amount of solder paste of printing before the control soldering makes the height h of soldering fillet 2 be no more than the height l of Cu matter round platform ₁Design, process and be connected according to above step, can obtain the CCGA interconnection that the solder welding spot reliability significantly improves.

Embodiment 2: referring to Fig. 2 a～2b; The interconnection structure of described raising CCGA device solder welding spot reliability; Form by the Cu post 1 in centre position and the soldering fillet 2 at two ends; Promptly adopt the two ends of the Cu post 1 in a plurality of centre positions that lead-free brazing will be arranged in array to be soldered to respectively to form on the metal film pad 5 on metal film pad 5 and the printed circuit board (PCB) 4 on the corresponding chip carrier substrate 3, wherein the two ends of Cu post 1 are processed to billiard table shape; And in order to keep the encapsulation order; The soldering fillet 2 at two ends approximately differs two kinds of lead-free brazing solderings of 100 ℃ by fusing point respectively and forms; Wherein, what printed circuit board (PCB) 4 one sides adopted is the general lead-free brazing of low-melting surface-assembled, and the concrete implementation procedure of described interconnection structure is:

Wherein: l is that post is high; D is a column diameter, i.e. the diameter of the cylinder 1-1 of Cu post 1; ρ is a resistivity;

Step 3, confirm the scope of cylinder 1-1 diameter d based on packaging density: under the constant situation of packaging density; Be under the constant situation of metal film pad diameter D and the solder pad space length of upper and lower base plate; For the good wet that guarantees soldering fillet 2 is connected with soldering, cylinder 1-1 diameter d maximum is no more than 1/3 of pad diameter D;

Step 5, processing meet the Cu post 1 of step 4 geomery requirement, during 1 machine-shaping of Cu post, control the base diameter d of the Cu matter billiard table part at its two ends ₁Be 1.5 times to 2 times of Cu cylinder 1-1 diameter d, control Cu matter billiard table height l ₁Approximate 0.75 times to 1 times of Cu cylinder 1-1 diameter d;

Step 6, elder generation adopt dystectic lead-free brazing; Like SnAg18; All Cu post 1 one ends that are the face array arrangement are soldered on the metal film pad 5 of chip carrier substrate 3 one sides; And then adopt the general lead-free brazing of more low-melting surface-assembled, like Sn3.0Ag0.5Cu, all other ends that are the Cu post 1 of face array arrangement are soldered on the metal film pad 5 of printed circuit board (PCB) 4 one sides.The amount of solder paste of printing before the control soldering makes the height h of soldering fillet 2 be no more than the height l of Cu matter billiard table ₁Design, process and be connected according to above step, can obtain the CCGA interconnection that the solder welding spot reliability significantly improves.

Embodiment 3: referring to Fig. 3 a～3b; The interconnection structure of described raising CCGA device solder welding spot reliability; Form by the Cu post 1 in centre position and the soldering fillet 2 at two ends; Promptly adopt the two ends of the Cu post 1 in a plurality of centre positions that lead-free brazing will be arranged in array to be soldered to respectively to form on the metal film pad 5 on metal film pad 5 and the printed circuit board (PCB) 4 on the corresponding chip carrier substrate 3, wherein the two ends of Cu post 1 are processed to segment shape (the segment height is greater than the radius of ball); And in order to keep the encapsulation order; The soldering fillet 2 at two ends approximately differs two kinds of lead-free brazing solderings of 100 ℃ by fusing point respectively and forms; Wherein, what printed circuit board (PCB) 4 one sides adopted is the general lead-free brazing of low-melting surface-assembled, and the concrete implementation procedure of described interconnection structure is:

Step 2, confirm diameter d and the height l scope of Cu post 1 of the cylinder 1-1 of Cu post 1 based on rigidity requirement: have enough rigidity under the effect of structure gravity and mechanical external force load in thermal deformation load on it for guaranteeing Cu post 1; The diameter d of Cu cylinder 1-1 should be not less than 0.20mm, and the height l of Cu post 1 is not more than 3.50mm;

Step 3, confirm the scope of Cu cylinder 1-1 diameter d based on packaging density: under the constant situation of packaging density; Be under the constant situation of metal film pad diameter D and the solder pad space length of upper and lower base plate; For the good wet that guarantees soldering fillet 2 is connected with soldering, Cu cylinder 1-1 diameter d maximum is no more than 2/5 of pad diameter D;

Step 5, processing meet the Cu post 1 of step 4 geomery requirement, during 1 machine-shaping of Cu post, control the maximum diameter d of the Cu matter segment part at its two ends ₁Be about 1.5 times to 2 times of cylinder 1-1 diameter d, control Cu matter segment part height l ₁Approximate 1.5 times to 2 times of cylinder 1-1 diameter d;

Step 6, elder generation adopt dystectic lead-free brazing; Like SnAg18; All Cu post 1 one ends that are the face array arrangement are soldered on the metal film pad 5 of chip carrier substrate 3 one sides; And then adopt the general lead-free brazing of more low-melting surface-assembled, like Sn3.0Ag0.5Cu, all other ends that are the Cu post 1 of face array arrangement are soldered on the metal film pad 5 of printed circuit board (PCB) 4 one sides.The amount of solder paste of printing before the control soldering makes the height h of soldering fillet 2 be no more than Cu matter segment height l partly ₁Design, process and be connected according to above step, can obtain the CCGA interconnection that the solder welding spot reliability significantly improves.

Press the foregoing description; Design the improvement interconnection structure of following CCGA device; The diameter D of the metal film pad 5 of ceramic chip carrier substrate 3 and printed circuit board (PCB) 4 is 0.80mm, and Cu cylinder 1-1 diameter d is 0.25mm, and the height l of Cu post 1 is 2.46mm; Cu matter termination, the two ends 1-2 of Cu post 1 is billiard table shape, billiard table shape bottom surface diameter d ₁Be 0.50mm, billiard table form height degree l ₁Be 0.25mm, two ends adopt Sn18Ag and Sn3.0Ag0.5Cu lead-free brazing to realize that soldering is connected respectively, and the height h of the soldering fillet 2 of formation is 2/3 of a Cu matter termination 1-2 height.The result of finite element of this interconnection structure shows; (its Cu post height l is that 2.46mm, Cu column diameter d are 0.25mm with the common Cu post CCGA interconnection of equal height l, same diameter d; The common Cu cylinder of mentioning in the background technology) compares; The peak stress of interconnection structure and peak strain are all transferred to good Cu post 1 inside of performance; The inner maximum equivalent plastic strain value of the soldering fillet that performance is weak under thermal cycle load and the bending load can be reduced to 1/10 of common Cu post CCGA at least, and promptly the CCGA of Cu pole interconnection can improve 10 times device lifetime.

The unit of the geometric shape parameters of the Cu post that the present invention is mentioned is mm.

Claims

1. interconnection structure that improves CCGA device solder welding spot reliability; Said interconnection structure comprises Cu post (1) and is positioned at the soldering fillet (2) at Cu post (1) two ends; Said interconnection structure is used to realize metal film pad (5) and the machinery between the metal film pad (5) on the printed circuit board (PCB) (4) on chip or the chip carrier substrate (3) and be electrically connected; It is characterized in that: said Cu post (1) is made up of the cylinder of processing one (1-1) and two terminations (1-2); It is the rotational-like of bus that each termination (1-2) is with straight line or circular arc line; Cylinder (1-1) be positioned at be back between two terminations (1-2) that are provided with and the three coaxial, seamlessly transit between cylinder (1-1) and termination (1-2); The height (h) of soldering fillet (2) is less than the height (l of termination (1-2) ₁).

2. a kind of interconnection structure that improves CCGA device solder welding spot reliability according to claim 1 is characterized in that: each termination (1-2) is shaped as truncated cone-shaped; Each processes one with the upper bottom surface of a termination (1-2) two ends of cylinder (1-1).

3. a kind of interconnection structure that improves CCGA device solder welding spot reliability according to claim 1 is characterized in that: each termination (1-2) is shaped as the billiard table shape that the bottom surface radius is the radius of a ball; Each processes one with the upper bottom surface of a termination (1-2) two ends of cylinder (1-1).

4. a kind of interconnection structure that improves CCGA device solder welding spot reliability according to claim 1 is characterized in that: each termination (1-2) is shaped as height greater than the segment shape of the radius of a ball; The two ends of cylinder (1-1) each with a termination (1-2) on face directly and process one.

5. a kind of interconnection structure that improves CCGA device solder welding spot reliability according to claim 2; It is characterized in that: the diameter (d) of cylinder (1-1) is more than or equal to 0.20mm and smaller or equal to 1/3 of the diameter (D) of metal film pad (5), the height (l) of Cu post (1) is more than or equal to 1.50mm and smaller or equal to 3.00mm; Bottom surface diameter (the d of the truncated cone-shaped termination (1-2) of Cu post (1) ₁) be 1.5 times to 2 times of cylinder (1-1) diameter (d), the height (l of truncated cone-shaped termination (1-2) ₁) more than or equal to the diameter (d) of cylinder (1-1) 1/2nd and smaller or equal to truncated cone-shaped termination (1-2) bottom surface diameter (d ₁) 1/2nd.

6. a kind of interconnection structure that improves CCGA device solder welding spot reliability according to claim 3; It is characterized in that: the diameter (d) of cylinder (1-1) is more than or equal to 0.20mm and smaller or equal to 1/3 of metal film pad (5) diameter (D), and the height (l) of Cu post (1) is more than or equal to 1.50mm and smaller or equal to 3.00mm; Bottom surface diameter (the d of the billiard table shape termination (1-2) of Cu post (1) ₁) be 1.5 times to 2 times of cylinder (1-1) diameter (d), the height (l of billiard table shape termination (1-2) ₁) be 0.75 times to 1 times of cylinder (1-1) diameter (d).

7. a kind of interconnection structure that improves CCGA device solder welding spot reliability according to claim 4; It is characterized in that: the diameter (d) of cylinder (1-1) is more than or equal to 0.20mm and smaller or equal to 2/5 of metal film pad (5) diameter (D), and the height (l) of Cu post (1) is more than or equal to 2.00mm and smaller or equal to 3.50mm; Bulb diameter (the d of segment shape termination (1-2) ₁) be 1.5 times to 2 times of cylinder (1-1) diameter (d), the height (l of segment shape termination (1-2) ₁) be 1.5 times to 2 times of cylinder (1-1) diameter (d).

8. the implementation method of the interconnection knot of the described raising of a claim 1 CCGA device solder welding spot reliability, it is characterized in that: said method realizes according to following steps:

Step 1, preparation Cu post (1): to burning ball or the mould that utilizes given shape behind the ball is again burnt at the two ends of copper coin post silk burns Cu ball is implemented to push in the two ends of copper coin post silk, with the shape of the formation described termination of claim (1) (1-2) at an end of silk;

Step 2, elder generation are printed onto the solder(ing) paste of an amount of high-melting point lead-free solder SnAg18 on a plurality of metal film pads (5) that are arranged in array of chip carrier substrate (3) one sides; Also vertically be placed into an end centering of a plurality of Cu posts (1) on corresponding a plurality of metal film pads (5); One end of a plurality of Cu posts (1) once is soldered on a plurality of metal film pads (5) of chip carrier substrate (3) one sides, and brazing temperature is controlled at above 20～40 ℃ of solder liquidus temperature; The amount of solder paste of control printing makes the height (h) of the soldering fillet (2) of formation be no more than the height (l of the termination (1-2) of Cu post (1) ₁);

Step 3, solder(ing) paste that then will an amount of more low-melting lead-free brazing Sn3.0Ag0.5Cu are printed onto on a plurality of metal film pads (5) that are arranged in array of printed circuit board (PCB) (4) one sides; Also vertically be placed into the other end centering of a plurality of Cu posts (1) on a plurality of metal film pads (5) of corresponding printed circuit board (PCB) (4) one sides; The other end of a plurality of Cu posts (1) once is soldered on a plurality of metal film pads (5) of printed circuit board (PCB) (4) one sides, and brazing temperature is controlled at above 20～40 ℃ of solder liquidus temperature; The amount of solder paste of control printing makes the height (h) of soldering fillet (2) be no more than the height (l of the termination (1-2) of Cu post (1) ₁);