CN113677104A - LGA device low-void-rate welding process method - Google Patents
LGA device low-void-rate welding process method Download PDFInfo
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- CN113677104A CN113677104A CN202110997992.XA CN202110997992A CN113677104A CN 113677104 A CN113677104 A CN 113677104A CN 202110997992 A CN202110997992 A CN 202110997992A CN 113677104 A CN113677104 A CN 113677104A
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- lga
- soldering
- soldering paste
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- lga device
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
- H05K3/3494—Heating methods for reflowing of solder
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10613—Details of electrical connections of non-printed components, e.g. special leads
- H05K2201/10621—Components characterised by their electrical contacts
- H05K2201/10719—Land grid array [LGA]
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/04—Soldering or other types of metallurgic bonding
- H05K2203/043—Reflowing of solder coated conductors, not during connection of components, e.g. reflowing solder paste
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Electric Connection Of Electric Components To Printed Circuits (AREA)
Abstract
The invention provides a low-voidage welding process method for an LGA device, which comprises the steps of placing the LGA device on an LGA pre-tinning tool base, pre-tinning a steel mesh through the LGA device, printing soldering paste on a device bonding pad, then placing the LGA device pre-printed with the soldering paste in a hot air reflow soldering furnace for reflow soldering, bridging the steel mesh soldering paste for printing, placing a printed board printed with the soldering paste in a chip mounter for chip mounting, placing the printed board on which the chip mounting is finished in the hot air reflow soldering furnace for reflow soldering. The invention can effectively reduce the welding voidage during the LGA welding and improve the qualification rate of products by adopting the mode of combining the pre-tinning of devices and the opening of special steel meshes. In addition, the process method is simple, no additional process equipment is added, and the method has wide operability.
Description
Technical Field
The invention relates to the field of patches, in particular to a printed board assembly assembling process and a surface-mounted device assembling process.
Background
In various types of electronic equipment, printed circuit boards are used as mounting substrates on which electronic and electromechanical components, devices or other printed circuit board assemblies are mounted, and printed board assemblies for electrical interconnection by means of printed wiring on the boards are core components and basic elements. Along with product lightweight, miniaturized requirement, components and parts encapsulation size is constantly reduced on the printed-board components and parts, and the figure is constantly increased, leads to solder joint quantity constantly to improve when solder joint size reduces. Lga (land Grid array) packages are surface array packages and are widely used because of their small package size, low mounting height, and high reliability. LGA devices are pin-less soldered, and typically the pads are square pads. Different from widely used BGA devices, the LGA packaging device only has a metal terminal or a welding pad at the bottom of a packaging body, does not have a welding ball, and directly replaces the welding ball or a welding column by using a mode of printing soldering paste during welding. And because the height of the welding spot is reduced, the performance of the product in bending, vibration, falling and other tests can be effectively improved by the LGA package, and the reliability of the product is improved. In addition, the pin-free device reduces one process in the chip manufacturing process, reduces the manufacturing cost, and provides convenience for the transportation of the device, so the pin-free device has wide application prospect.
However, since the LGA device has a low bonding height, a bonding defect is also easily generated. When hot air reflow soldering is performed, the welding voidage is high. The void formation is caused directly by the volatilization of the flux components during the melting of the solder paste or by the failure of the gas generated by the chemical reaction of the flux components with the oxide layer to escape from the solder during volatilization. The requirement of special inspection of the voidage of the LGA device after welding is not existed in the industry, but many units are inspected according to the requirement of the voidage of a reference BGA (generally not more than 25%). When the conventional SMT process (steel mesh printing soldering paste-patch-welding) is used, the welding voidage of the LGA device is generally high, and the inspection requirements cannot be met. Therefore, there is a need to improve the existing SMT process to meet the requirements of LGA device soldering inspection.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a low-void-rate welding process method for an LGA device. In order to overcome the defect that the welding process of the LGA device is easy to generate large voidage of welding spots, the invention provides the low voidage welding process method of the LGA device.
The technical scheme adopted by the invention for solving the technical problem comprises the following steps:
(1) pre-tinning of LGA devices:
placing the LGA device on an LGA pre-tinning tool base, pre-tinning a steel mesh through the LGA device, and printing soldering paste on a device pad, wherein the steel mesh is made of a steel sheet with a nano coating; then placing the LGA device with the pre-printed soldering paste into a hot air reflow soldering furnace for reflow soldering;
(2) and (3) bridge steel mesh soldering paste printing:
placing a printed board to be welded in a soldering paste printer, and printing soldering paste on a bonding pad on the surface of the printed board through a large steel mesh, wherein an LGA device opening on the large steel mesh adopts a straight bridge mode;
(3) surface mounting:
placing the printed board printed with the soldering paste in a chip mounter for chip mounting, wherein a negative value indicates that the device is not in contact with the reference surface of the printed board when being placed in a mounting manner;
(4) and (3) reflow soldering:
and placing the printed board subjected to the surface mounting in a hot air reflow furnace, and performing reflow soldering.
In the step (1), the opening size of the steel sheet is 0.6mm multiplied by 0.6mm to 0.7mm multiplied by 0.7mm, and the thickness is 0.2mm to 0.25 mm.
And (2) during reflow soldering in the step (1), the reflow soldering peak temperature is 215-225 ℃, and the reflow time is 30-60S.
The granularity of the selected soldering paste is 3, and the size of the selected soldering paste is 25-45 mu m.
In the step (2), the thickness of the large steel mesh is 0.1 mm-0.12 mm, the width of the bridge is 0.12 mm-0.15 mm, and the printing pressure is 2.6 Kg-2.8 Kg.
And (4) when the patch is pasted in the step (3), the pasting height of the LGA device is set to be-0.1 mm-0 mm.
In the step (4), the reflow soldering peak temperature is 225-235 ℃, and the reflow time is 40-60S.
The invention has the advantages that the traditional SMT process is improved by adopting a mode of combining the pre-tinning of the device and the opening of the special steel mesh, and the novel low-void-rate welding process method for the LGA device is provided. In addition, the process method is simple, no additional process equipment is added, and the method has wide operability.
Drawings
FIG. 1 is a process flow diagram of the present invention.
FIG. 2 is a pictorial view of a pre-tinning tool of the present invention; wherein: fig. 2(a) is a real diagram of a base, and fig. 2(b) is a real diagram of a pre-tinned steel mesh.
FIG. 3 is a partial physical diagram of an opening of a bridge in a linear shape of a large steel mesh LGA device according to the present invention.
Figure 4 is an X-ray view of an LGA device of the present invention using a novel LGA soldering process.
Figure 5 is an X-ray view of an LGA device of the present invention soldered using conventional techniques.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
The invention provides a low-void-rate welding process method for an LGA device, which comprises the following steps of:
(1) pre-tinning of a device:
placing the LGA device in a soldering paste printer, pre-coating a tin steel mesh on the LGA device shown in figure 2, wherein the steel mesh is made of a steel sheet with a nano coating, the size of an opening is 0.6mm multiplied by 0.6 mm-0.7 mm multiplied by 0.7mm, and the thickness is 0.2 mm-0.25 mm; printing soldering paste on the device bonding pad, wherein the granularity of the selected soldering paste is 3, and the size of the selected soldering paste is 25-45 mu m; and then placing the LGA device with the pre-printed soldering paste into a hot air reflow soldering furnace for reflow soldering, wherein the peak temperature of reflow soldering is 215-225 ℃, and the reflow time is 30-60S.
(2) And (3) bridge steel mesh soldering paste printing:
the printed board to be welded is placed in a soldering paste printer, soldering paste printing is carried out on the surface bonding pad of the printed board through a large steel mesh shown in figure 3, the thickness of the steel mesh is 0.1-0.12 mm, the width of a bridging is 0.12-0.15 mm, the granularity of the selected soldering paste is 3, the size of the selected soldering paste is 25-45 mu m, and the printing pressure is 2.6-2.8 Kg.
(3) Surface mounting:
and placing the printed board printed with the soldering paste into a chip mounter for chip mounting, wherein the mounting height of the LGA device is set to be-0.1 mm-0 mm.
(4) And (3) reflow soldering:
and placing the printed board after the surface mounting in a hot air reflow oven, and performing reflow soldering, wherein the peak temperature of the reflow soldering is 225-235 ℃, and the reflow time is 40-60S.
In order to verify the improvement of the present invention in terms of the voidage at the solder joints of LGA devices, the following steps were performed.
Firstly, preparing a welding sample containing an LGA device.
(1) Pre-tinning of a device:
placing the LGA device in a solder paste printer, pre-coating a tin steel mesh on the LGA device shown in figure 2, wherein the steel mesh is made of a steel sheet with a nano coating, the size of an opening is 0.7mm multiplied by 0.7mm, and the thickness is 0.25 mm; printing soldering paste on the device bonding pad, wherein the granularity of the selected soldering paste is 3, and the size of the selected soldering paste is 25-45 mu m; and then placing the LGA device with the pre-printed soldering paste into a hot air reflow soldering furnace for reflow soldering, wherein the peak temperature of reflow soldering is 218 ℃, and the reflow time is 42S.
(2) And (3) bridge steel mesh soldering paste printing:
the printed board to be welded is placed in a soldering paste printer, soldering paste printing is carried out on the surface bonding pad of the printed board through a large steel mesh shown in figure 3, the thickness of the steel mesh is 0.12mm, the width of a bridging structure is 0.12mm, the granularity of the selected soldering paste is 3, the size of the selected soldering paste ranges from 25 micrometers to 45 micrometers, and the printing pressure is 2.6 Kg.
(3) Surface mounting:
and placing the printed board printed with the soldering paste into a chip mounter for chip mounting, wherein the mounting height of the LGA device is set to be-0.1 mm.
(4) And (3) reflow soldering:
and placing the printed board subjected to the surface mounting in a hot air reflow furnace, and performing reflow soldering, wherein the peak temperature of the reflow soldering is 231 ℃, and the reflow time is 54S.
(II) testing of welding quality
In order to highlight the effect of the present invention, a welding comparative sample was also prepared according to a conventional process.
FIG. 4 is an X-ray of an LGA device after a novel LGA bonding process, and FIG. 5 is an X-ray of an LGA device bonded by a conventional process. It can be seen that the sample void ratio is below 10% and no welding defect exists after the novel process is adopted. In conclusion, the defect of high welding spot void ratio after the welding of the LGA device is effectively overcome.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.
Claims (7)
1. A low-void-rate welding process method of an LGA device is characterized by comprising the following steps:
(1) pre-tinning of LGA devices:
placing the LGA device on an LGA pre-tinning tool base, pre-tinning a steel mesh through the LGA device, and printing soldering paste on a device pad, wherein the steel mesh is made of a steel sheet with a nano coating; then placing the LGA device with the pre-printed soldering paste into a hot air reflow soldering furnace for reflow soldering;
(2) and (3) bridge steel mesh soldering paste printing:
placing a printed board to be welded in a soldering paste printer, and printing soldering paste on a bonding pad on the surface of the printed board through a large steel mesh, wherein an LGA device opening on the large steel mesh adopts a straight bridge mode;
(3) surface mounting:
placing the printed board printed with the soldering paste in a chip mounter for chip mounting, wherein a negative value indicates that the device is not in contact with the reference surface of the printed board when being placed in a mounting manner;
(4) and (3) reflow soldering:
and placing the printed board subjected to the surface mounting in a hot air reflow furnace, and performing reflow soldering.
2. The LGA device low-void-rate bonding process of claim 1, wherein:
in the step (1), the opening size of the steel sheet is 0.6mm multiplied by 0.6mm to 0.7mm multiplied by 0.7mm, and the thickness is 0.2mm to 0.25 mm.
3. The LGA device low-void-rate bonding process of claim 1, wherein:
and (2) during reflow soldering in the step (1), the reflow soldering peak temperature is 215-225 ℃, and the reflow time is 30-60S.
4. The LGA device low-void-rate bonding process of claim 1, wherein:
the granularity of the selected soldering paste is 3, and the size of the selected soldering paste is 25-45 mu m.
5. The LGA device low-void-rate bonding process of claim 1, wherein:
in the step (2), the thickness of the large steel mesh is 0.1 mm-0.12 mm, the width of the bridge is 0.12 mm-0.15 mm, and the printing pressure is 2.6 Kg-2.8 Kg.
6. The LGA device low-void-rate bonding process of claim 1, wherein:
and (4) when the patch is pasted in the step (3), the pasting height of the LGA device is set to be-0.1 mm-0 mm.
7. The LGA device low-void-rate bonding process of claim 1, wherein:
in the step (4), the reflow soldering peak temperature is 225-235 ℃, and the reflow time is 40-60S.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110997992.XA CN113677104A (en) | 2021-08-27 | 2021-08-27 | LGA device low-void-rate welding process method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110997992.XA CN113677104A (en) | 2021-08-27 | 2021-08-27 | LGA device low-void-rate welding process method |
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| CN113677104A true CN113677104A (en) | 2021-11-19 |
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| CN202110997992.XA Pending CN113677104A (en) | 2021-08-27 | 2021-08-27 | LGA device low-void-rate welding process method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114423180A (en) * | 2022-02-18 | 2022-04-29 | 北京柏瑞安电子技术有限公司 | QFN lead-free low-voidage welding method |
| CN114430625A (en) * | 2022-01-25 | 2022-05-03 | 中国船舶重工集团公司第七二四研究所 | One-time welding process for reducing voidage of LGA welding spots |
| CN114654035A (en) * | 2022-04-29 | 2022-06-24 | 天津光电惠高电子有限公司 | Method for reducing LGA device welding cavity by using prefabricated solder |
| CN116321796A (en) * | 2023-01-12 | 2023-06-23 | 成都电科星拓科技有限公司 | LGA bottom surface solder paste printing soldering-assisted packaging device and technology |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5878942A (en) * | 1995-09-22 | 1999-03-09 | International Business Machines Corporation | Soldering method and soldering apparatus |
| CN105007695A (en) * | 2015-07-29 | 2015-10-28 | 无锡市同步电子制造有限公司 | LGA welding process method in printed circuit board processing |
| CN107124835A (en) * | 2017-05-25 | 2017-09-01 | 杭州晶志康电子科技有限公司 | Reflow Soldering paster technique |
| CN109152231A (en) * | 2018-09-12 | 2019-01-04 | 成都京蓉伟业电子有限公司 | A kind of double QFN integrated circuit welding procedure |
| CN109688727A (en) * | 2018-12-26 | 2019-04-26 | 无锡市同步电子制造有限公司 | One kind having lead pb-free solder method |
| CN110139502A (en) * | 2019-05-31 | 2019-08-16 | 深圳市英创立电子有限公司 | Pcb board surface mount process |
-
2021
- 2021-08-27 CN CN202110997992.XA patent/CN113677104A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5878942A (en) * | 1995-09-22 | 1999-03-09 | International Business Machines Corporation | Soldering method and soldering apparatus |
| CN105007695A (en) * | 2015-07-29 | 2015-10-28 | 无锡市同步电子制造有限公司 | LGA welding process method in printed circuit board processing |
| CN107124835A (en) * | 2017-05-25 | 2017-09-01 | 杭州晶志康电子科技有限公司 | Reflow Soldering paster technique |
| CN109152231A (en) * | 2018-09-12 | 2019-01-04 | 成都京蓉伟业电子有限公司 | A kind of double QFN integrated circuit welding procedure |
| CN109688727A (en) * | 2018-12-26 | 2019-04-26 | 无锡市同步电子制造有限公司 | One kind having lead pb-free solder method |
| CN110139502A (en) * | 2019-05-31 | 2019-08-16 | 深圳市英创立电子有限公司 | Pcb board surface mount process |
Non-Patent Citations (3)
| Title |
|---|
| 倪宏俊: "BGA芯片的返修与锡球重整", 《印制电路信息》 * |
| 徐婷婷: "LGA封装器件焊接工艺技术研究", 《中国硕士学位论文全文数据库（信息科技辑）》 * |
| 王文龙: "LGA器件焊点缺陷分析及解决措施", 《电子工艺技术》 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114430625A (en) * | 2022-01-25 | 2022-05-03 | 中国船舶重工集团公司第七二四研究所 | One-time welding process for reducing voidage of LGA welding spots |
| CN114430625B (en) * | 2022-01-25 | 2023-12-12 | 中国船舶集团有限公司第七二四研究所 | One-time welding process for reducing cavity rate of LGA welding spot |
| CN114423180A (en) * | 2022-02-18 | 2022-04-29 | 北京柏瑞安电子技术有限公司 | QFN lead-free low-voidage welding method |
| CN114654035A (en) * | 2022-04-29 | 2022-06-24 | 天津光电惠高电子有限公司 | Method for reducing LGA device welding cavity by using prefabricated solder |
| CN114654035B (en) * | 2022-04-29 | 2024-05-24 | 天津光电惠高电子有限公司 | Method for reducing LGA device welding cavity by using prefabricated solder |
| CN116321796A (en) * | 2023-01-12 | 2023-06-23 | 成都电科星拓科技有限公司 | LGA bottom surface solder paste printing soldering-assisted packaging device and technology |
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