CN105618882A - Packaging method for soldered joint - Google Patents

Abstract

The invention discloses a packaging method for a soldered joint. By the adoption of the packaging method, the technical problem that according to an existing packaging method, a soldered joint is poor in strength is solved. According to the technical scheme, a right quadrangular micro-structure groove is machined in the surface of an electronic component copper plate through a laser device; the prefabricated micro-structure groove is cleaned; wetting experiment is conducted on the smooth surface of the copper plate and the surface of the micro-structure groove through Sn-Ag-Cu solder, and wetting angles of the copper plate and the micro-structure groove are measured; the filling condition and corrosion condition of the Sn-Ag-Cu solder under different micro structures are observed; and soldering is conducted on the copper plate with the prefabricated micro-structure groove with Sn-Ag-Cu as the solder. Due to the existence of the right quadrangular micro-structure groove in the surface of the copper plate, the wetting angle, which is 59.2 degrees in the prior art, of the cooper plate is decreased to 26.3 degrees, metallurgical bonding of the soldered joint is facilitated, and the strength, which is 72.4+/-3.8 MPa in the prior art, of the soldered joint is improved to 85+/-4.5 MPa.

Description

The method for packing of brazed joint

Technical field

The present invention relates to a kind of method for packing, in particular to the method for packing of a kind of brazed joint.

Background technology

Progress along with science and technology and the attention to lead element hazardness, electronic product is carried out unleaded gradually, thus the interconnection materials such as solder are proposed new requirement, tradition braze material is such as Sn-Pb binary eutectic alloy, although having the features such as weldability is good, excellent property, cost are excellent, progressively replaced by lead-free brazing. In all lead-free brazings applied, there is due to Sn-Ag-Cu solder superior reliability and the consistency good with electronic component, it is considered as one of the most promising lead-free solder alloy system. But, the wetting and spreading energy force rate Sn-Pb solder of Sn-Ag-Cu solder is poor, and the control sprawled is poor, and this makes easily to produce de-pricker, leakage pricker, the defects such as pricker of overflowing in accurate electron device.

Copper has the advantages such as good pyro-conductivity, low thermal expansivity, good solderability and solidity to corrosion, good processability, lower cost, so major part pin connector and lead frame all take copper production in electronic devices and components. But, the wetting angle of Sn-Ag-Cu solder on copper coin surface is 59.2 ��, and the intensity of brazed joint is 72.4 �� 3.8MPa. In order to solve the problem of Sn-Ag-Cu solder wetting and spreading in brazing process, document " D.QYu; JZhao; LWang.Improvementonthemicrostructurestability; mechanicalandwettingpropertiesofSn Ag Culead-freesolderwiththeadditionofrareearthelements [J] .Journalofalloysandcompounds; 2004,376 (1): 170-175. " discloses a kind of method for packing. The method by adding rare earth element in Sn-Ag-Cu solder, solve the wetting out problems of Sn-Ag-Cu solder to a certain extent, but joint produces intermetallic compound, increase the defect at joint interface place, to the precision and the performance that improve brazed joint, reduce joint yardstick and all there is more disadvantageous impact.

Summary of the invention

In order to overcome the deficiency of existing method for packing soldering joint strength difference, the present invention provides the method for packing of a kind of brazed joint. The method adopts laser apparatus to process the four-prism shape microstructured groove being highly 20 �� 2 ��m with width dimensions on electronic devices and components copper coin surface, prefabricated microstructured groove is carried out pickling and ultrasonic cleaning, use Sn-Ag-Cu solder that copper coin smooth surface and microstructured groove surface are carried out wetting experiment respectively, test its wetting angle; In the corrosion situation of the filling situation of light Microscopic observation Sn-Ag-Cu solder under different microstructure and microstructure; Take Sn-Ag-Cu as solder, soldering implemented by the copper coin of prefabricated microstructured groove. Due to the existence of electronic devices and components copper coin surface four-prism shape microstructured groove, the wetting angle of Sn-Ag-Cu solder on copper coin surface is made to be reduced to 26.3o from the 59.2o of background technology, facilitating the metallurgical binding of brazed joint, the intensity of brazed joint is promoted to 85 �� 4.5MPa from 72.4 �� 3.8MPa of background technology.

The technical solution adopted for the present invention to solve the technical problems: the method for packing of a kind of brazed joint, is characterized in comprising the following steps:

Step one, with SiC sand paper by electronic devices and components copper coin surface finish and polishing, then use ultrasonic cleaning and dry, use the microstructure that femto-second laser is four-prism shape in copper coin surface working shape, its width and be highly 20 �� 2 ��m, the groove width between quadrangular is respectively 10��40 ��m.

The HNO that concentration is 30% put into by step 2, copper coin by prefabricated four-prism shape microstructure₃Middle ultrasonic cleaning 1��2min, to remove surface contaminants and greasy dirt, then by clean water, then absorbs water with dehydrated alcohol and blows dry stand-by.

Step 3, in O2C wetting angle measuring system, by the Sn-Ag-Cu solder weldering ball that diameter is 0.6mm, in dehydrated alcohol, ultrasonic cleaning 10��12min removes surface impurity and greasy dirt, treated Sn-Ag-Cu solder is welded the micro-structure surface center that ball is placed on different size, it is rapidly heated to brazing temperature with the heating rate of 40��50 DEG C/min after starting video recording device, with the rate of temperature fall fast cooling of 40��50 DEG C/min after insulation 5��6min, record the video data of whole thawing wet processes, choose wetting beginning and carry out sectional drawing with the end moment, measure wetting angle.

Step 4, being solder taking Sn-Ag-Cu, implement soldering on the copper coin of prefabricated microstructure, soldering is incubated 5��7min at 320��330 DEG C.

The invention has the beneficial effects as follows: the method adopts laser apparatus to process the four-prism shape microstructured groove being highly 20 �� 2 ��m with width dimensions on electronic devices and components copper coin surface, prefabricated microstructured groove is carried out pickling and ultrasonic cleaning, use Sn-Ag-Cu solder that copper coin smooth surface and microstructured groove surface are carried out wetting experiment respectively, test its wetting angle; In the corrosion situation of the filling situation of light Microscopic observation Sn-Ag-Cu solder under different microstructure and microstructure; Take Sn-Ag-Cu as solder, soldering implemented by the copper coin of prefabricated microstructured groove. Due to the existence of electronic devices and components copper coin surface four-prism shape microstructured groove, the wetting angle of Sn-Ag-Cu solder on copper coin surface is made to be reduced to 26.3 �� from the 59.2 of background technology ��, facilitating the metallurgical binding of brazed joint, the intensity of brazed joint is promoted to 85 �� 4.5MPa from 72.4 �� 3.8MPa of background technology.

Below in conjunction with the drawings and specific embodiments, the present invention done detailed explanation.

Accompanying drawing explanation

Fig. 1 is the light microscopic photo of the different groove width of microstructure adopting femto-second laser to process on the surface at copper coin in the method for packing of brazed joint of the present invention. Fig. 1 (a) groove width 10 ��m, Fig. 1 (b) groove width 20 ��m, Fig. 1 (c) groove width 30 ��m, Fig. 1 (d) groove width 40 ��m.

Fig. 2 be brazed joint of the present invention method for packing in the wetting angle photo of different size microstructure. Fig. 2 (a) smooth surface, Fig. 2 (b) groove width 10 ��m, Fig. 2 (c) groove width 20 ��m, Fig. 2 (d) groove width 30 ��m, Fig. 2 (e) groove width 40 ��m.

Fig. 3 be brazed joint of the present invention method for packing in the change curve of wetting angle and microstructured groove width.

Fig. 4 be brazed joint of the present invention method for packing in photo after micro-structure surface corrosion. Fig. 4 (a) groove width 10 ��m, Fig. 4 (b) groove width 20 ��m, Fig. 4 (c) groove width 30 ��m, Fig. 4 (d) groove width 40 ��m.

Embodiment

With reference to Fig. 1-4. The method for packing concrete steps of brazed joint of the present invention are as follows:

Step one, with SiC sand paper by electronic devices and components copper coin surface finish and polishing, then use ultrasonic cleaning and dry, and use femto-second laser (model HSGQ-20W) in the microstructure that copper coin surface working shape is four-prism shape, its width and be highly 20 �� 2 ��m, the groove width between quadrangular is respectively 10 ��m, 20 ��m, 30 ��m and 40 ��m.

Step 2, surface micro-structure precision are extremely high, therefore can not it be polished or the operation such as polishing. It is the HNO of 30% to the wetting sample of prepared surface microstructure in concentration₃Middle ultrasonic cleaning 1��2min, to remove surface contaminants and greasy dirt, then by clean water, then absorbs water with dehydrated alcohol and blows dry stand-by.

Step 3, in the processing situation of light Microscopic observation microstructure and measure its size, verify that it meets experimental precision requirement.

Step 4, in O2C wetting angle measuring system, use the Sn-Ag-Cu solder weldering ball that diameter is 0.6mm, before experiment, in dehydrated alcohol, ultrasonic cleaning 10��12min removes surface impurity and greasy dirt, solder ball is placed on the micro-structure surface center of different size, it is rapidly heated to brazing temperature with the heating rate of 40��50 DEG C/min after starting video recording device, with the rate of temperature fall fast cooling of 40��50 DEG C/min to suitable temp after insulation 5��6min, record the video data of whole thawing wet processes, choose wetting beginning and carry out sectional drawing with the end moment, measure wetting angle.

Step 5, being cut along being perpendicular to wetting interface and be parallel to groove direction by wetting sample, be set into metallographic specimen, observe the slight corrosion of microstructure under light microscopic, solder can filling interface microstructure well.

Step 6, analytical test result, verify microstructure to Sn-Ag-Cu solder in mother metal moistened surface and the impact sprawled, pass through wetting experiment, demonstrate microstructure and Sn-Ag-Cu solder can be reduced to 26.3 �� in the wetting angle of red copper surface from 58.2o, demonstrate microstructure and can promote that solder is at the wetting and spreading on mother metal surface.

Step 7, it is solder taking Sn-Ag-Cu, soldering implemented by the copper coin of prefabricated microstructure, brazing tests is incubated 5��7min at 320��330 DEG C, " solder joint of lead-free brazing stretches and shearing test method " in Lead-Free Technology application reference standard is adopted to be tested by strength of welded joint, strength of joint brings up to 85 �� 4.5MPa from 72.4 �� 3.8MPa, and strength of joint improves 20%.

Claims (1)

1. the method for packing of a brazed joint, it is characterised in that comprise the following steps:

Step one, with SiC sand paper by electronic devices and components copper coin surface finish and polishing, then use ultrasonic cleaning and dry, use the microstructure that femto-second laser is four-prism shape in copper coin surface working shape, its width and be highly 20 �� 2 ��m, the groove width between quadrangular is respectively 10��40 ��m;

The HNO that concentration is 30% put into by step 2, copper coin by prefabricated four-prism shape microstructure₃Middle ultrasonic cleaning 1��2min, to remove surface contaminants and greasy dirt, then by clean water, then absorbs water with dehydrated alcohol and blows dry stand-by;

Step 3, in O2C wetting angle measuring system, by the Sn-Ag-Cu solder weldering ball that diameter is 0.6mm, in dehydrated alcohol, ultrasonic cleaning 10��12min removes surface impurity and greasy dirt, treated Sn-Ag-Cu solder is welded the micro-structure surface center that ball is placed on different size, it is rapidly heated to brazing temperature with the heating rate of 40��50 DEG C/min after starting video recording device, with the rate of temperature fall fast cooling of 40��50 DEG C/min after insulation 5��6min, record the video data of whole thawing wet processes, choose wetting beginning and carry out sectional drawing with the end moment, measure wetting angle,

Step 4, being solder taking Sn-Ag-Cu, implement soldering on the copper coin of prefabricated microstructure, soldering is incubated 5��7min at 320��330 DEG C.