CN207239482U - A kind of preformed soldering - Google Patents
A kind of preformed soldering Download PDFInfo
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- CN207239482U CN207239482U CN201720984762.9U CN201720984762U CN207239482U CN 207239482 U CN207239482 U CN 207239482U CN 201720984762 U CN201720984762 U CN 201720984762U CN 207239482 U CN207239482 U CN 207239482U
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- weld tabs
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- preformed soldering
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Abstract
The utility model provides a kind of preformed soldering, it includes weld tabs body, and in the longitudinal direction, the center thickness degree thicker than the edges of the weld tabs body is big；To the edge of both sides, thickness is in continuous transition at the center of the weld tabs body.Using the technical solution of the utility model, by controlling the shape of preformed soldering, center thickness degree thickness thicker than the edges is formed, in assembling, the stress point of weld tabs concentrates on weld tabs center, reduces weld tabs central contact thermal resistance；Gap is formed between weld tabs edge and soldered object, increases weld tabs edge thermal contact resistance.Form the bulk temperature gradient that central temperature is high, lip temperature is low when this welds weld tabs, orientation since center, gradually to edge fusing, wetting, promote, gas is effectively excluded, so that voidage when reducing welding.
Description
Technical field
The utility model belongs to technical field of soldering materials, more particularly to a kind of preformed soldering.
Background technology
With the development of microelectric technique, power tube device density is bigger, also tighter to the cooling requirements of assembly welding
It is severe.Welding cavity is reduced, is the key problem of high power device assembling.Although vacuum welding highly effective can be reduced, very
It is empty to eliminating, but low production efficiency, complex process.Reflow soldering is efficient, but reaches 40% using the welding voidage of tin cream
More than, seriously affect heat dissipation performance.
When big pad is welded using tin cream, empty generation, can be with mainly due to there is substantial amounts of organic solvent in tin cream
The 40%-50% of cumulative volume is accounted for, these solvents gradually volatilize in heating process is brazed, and a large amount of gases of generation, are closed in
After in pad, cavity is ultimately formed.
Preformed soldering is a kind of advanced welding material gradually risen recently, its composition includes laminar preforming tin
Piece and the scaling powder precoated shet on surface.Due to its registration, solder stable content, welding voidage is low and welding assisted agent residuals are few
The advantages of, it is particularly suitable for big pad, the welding occasion of high-quality requirement.Reflow Soldering is carried out using preformed soldering substitution tin cream
Connect, be a kind of effective means for reducing weldment voidage.Preformed soldering is a kind of laminar solder manufactured goods, with tin cream phase
Than, which employs the scaling powder of solid, therefore the volatile matter caused by without substantial amounts of organic solvent, so as to prevent and reduce
Cavity produces during welding.
As shown in Figure 1, in Reflow Soldering, plane weld tabs 1 is clipped in the middle by device 2 and pcb board 3, due to device 2 and pcb board 3
Block, plane weld tabs 1 can not be directly by hot wind and infrared lamps, and the heat of fusing, mostlys come from 4 He of device bonding pad
The heat transfer of PCB pads 5；Device bonding pad 4 and the size of PCB pads 5 are bigger, and the temperature difference at pad center and edge is bigger,
Therefore the temperature of whole pad shows uneven, low, the high spy in edge centered on the Temperature Distribution i.e. presentation of plane weld tabs 1
Point.
Solder is under brazing temperature, and the propulsion in its forward position, is by the temperature gradient on weld tabs when liquid solder wetting extends
Control.Since weld tabs lip temperature is high, central temperature is low, and solder fusing primarily occur ins outer ledge position, then in
The heart develops, and causes the gas at center to be enclosed in pad center and can not be escaped by the liquid solder in outside, is finally evolved into cavity.
Utility model content
For above technical problem, the utility model discloses a kind of preformed soldering, improves in preformed soldering welding
Empty problem.
In this regard, the technical solution adopted in the utility model is：
A kind of preformed soldering, it includes weld tabs body, and in the longitudinal direction, the center thickness of the weld tabs body compares side
Edge thickness is big；To the edge of both sides, thickness is in continuous transition at the center of the weld tabs body.
The heat transfer at interface, is mainly influenced by thermal contact resistance.And thermal contact resistance is mainly by contact, material and table
The control of surface roughness.Using the weld tabs of this technical solution in assembling, stress concentrates on weld tabs center, reduces center
Thermal contact resistance；Meanwhile edge substantially increases thermal contact resistance, therefore center and peripheral due to the presence of assembly clearance
Heat-transfer capability generate significant difference, it is high to form medium temperature, the low temperature gradient of lip temperature, make weld tabs directionally by
Melt, soak, promote to edge in center.This process can efficiently exclude gas, and reduce cavity.
It is further preferred that the good high temperature alloy net of certain thickness solderability can be implanted into weld tabs body, as
The skeleton of weld tabs, improves its Assembly stability.
As further improvement of the utility model, the center thickness of the weld tabs body is 1.5-5 times of edge thickness.
As further improvement of the utility model, the center thickness of the weld tabs body is 2-3 times of edge thickness.
As further improvement of the utility model, the thickness at center to the edge of any side of the weld tabs body becomes
Turn to the change of monotone decreasing.Further, thickness profiles from the center of the weld tabs body to the edge of any side,
Can be concave function, convex function, straight line or the combination of three, but must monotone decreasing.
As further improvement of the utility model, the center of the weld tabs body is central platform.
As further improvement of the utility model, the fifth wheel of the center of the weld tabs body to the edge of any side
Profile is camber line.
As further improvement of the utility model, on length direction or width, the weld tabs body is inlaid with
Wire, the fusing point of the wire are more than the fusing point of weld tabs body.
Preferably, the wire symmetrically lived apart is inlaid with the weld tabs body along its length, the wire prolongs
It is identical with the width of weld tabs body to stretch direction, the wire is symmetrical on weld tabs center line.
Preferably, high temperature wires cruciferous are inlayed on the weld tabs body.
Preferably, the wire is exposed to the surface of weld tabs body.
As further improvement of the utility model, the fusing point of the wire is more than 500 DEG C.
As further improvement of the utility model, the wire is copper wire, nickel wire or filamentary silver.
As further improvement of the utility model, the material of the weld tabs body is solder solder.
Further, the material of the weld tabs body is tin alloy solder, metal solder or indalloy.
As further improvement of the utility model, the surface precoating fluxing agent layer of the weld tabs body.
Compared with prior art, the beneficial effects of the utility model are：
Using the technical solution of the utility model, by controlling the shape of preformed soldering, form center thickness and compare edge
Thickness is thick, and in assembling, the stress point of weld tabs concentrates on middle part, reduces thermal resistance, and edge forms gap with soldered object,
The thermal resistance of increase, forms the temperature gradient that medium temperature is high, lip temperature is low, weld tabs is melted in welding since center,
Gas is effectively excluded, so that voidage when reducing welding.
Brief description of the drawings
Fig. 1 is the welding assembly schematic diagram of the plane weld tabs of the prior art.
Fig. 2 is the side view of the preformed soldering of the utility model embodiment 1.
Fig. 3 is the schematic perspective view of preformed soldering described in the utility model embodiment 1.
Fig. 4 is the side view of the preformed soldering of the utility model embodiment 2.
Fig. 5 is the schematic perspective view of the preformed soldering of the utility model embodiment 2.
Fig. 6 is the welding assembly schematic diagram of the preformed soldering of the utility model embodiment 2.
Fig. 7 is the side view of the preformed soldering of the utility model embodiment 3.
Fig. 8 is the schematic perspective view of the preformed soldering of the utility model embodiment 3.
Fig. 9 is the side view of the preformed soldering of the utility model embodiment 4.
Figure 10 is the schematic perspective view of the preformed soldering of the utility model embodiment 4.
Figure 11 is the structure diagram of the preformed soldering of the utility model embodiment 5.
Reference numeral includes：1- plane weld tabs, 2- devices, 3-PCB plates, 4- device bonding pads, 5-PCB pads, 6- nickel wires, 7-
High temperature wires；11- weld tabs center, 12- weld tabs edge, 13- central platforms, 14- gaps.
Embodiment
For clearer explanation the utility model embodiment or prior art, with reference to embodiment and attached drawing,
The utility model is described further.It will be clear that following embodiments are only some very typical embodiment party
Formula, all one of skill in the art principle of foundation the utility model in the case where not paying performing creative labour are made
Develop, all within scope of protection of the utility model.
Embodiment 1：
As shown in Figures 2 and 3, a kind of preformed soldering, is the rectangular sheet of a 10mmx10mm, material Sn-3.0Ag-
0.5Cu.The section of its length direction, bottom profile are plane, and top profile is outer convex, the thickness at weld tabs center 11
0.2mm, the thickness at weld tabs edge 12 is 0.1mm, and surface is coated with 1% scaling powder.This embodiment is very high applied to device thermal resistance,
Heat is mainly conducted to the scene of preformed soldering by PCB pads.During assembling, the cambered surface of weld tabs makes pad towards PCB pads
Heat is preferentially transferred to weld tabs center.After fusion temperature is warming up to, weld tabs is melted by weld tabs center 11, to weld tabs edge
12 wetting extensions, side by side except gas.
Control experiment is carried out using QFN pads, the voidage of gained is respectively：Use tin cream for 45%, using face bonding
Piece for 24%, the voidage of the present embodiment is 8%, well below the voidage of tin cream and plane weld tabs.
Embodiment 2：
As shown in Fig. 4 ~ Fig. 6, a kind of preformed soldering, be a 7mmx7mm rectangular sheet, material Sn-3.5Ag.Weldering
The center of piece is the central platform 13 that width is 2mm, and thickness 0.3mm, the thickness at weld tabs edge 12 is 0.1mm.Its length direction
Section, symmetrical above and below, symmetrical, central platform 13 passes through indent arc transition to weld tabs edge 12.This embodiment application
Scene relatively low in device thermal resistance, that heat passes through PCB pads and device bonding pad common conductive to preformed soldering.The present embodiment
In assembling, central platform 13 is contacted weld tabs with central platform shape with the middle part of device 2 and pcb board 3, that is, device weldering
The middle part of disk 4 and PCB pads 5 is directly direct with central platform 13, shape between weld tabs edge 12 and device bonding pad 4 and PCB pads 5
Into gap, more stablize when so assembling, be not easy to tilt.The stress point of weld tabs concentrates on central platform 13, reduces thermal resistance, and
Weld tabs edge 12 forms gap 14 with device bonding pad 4 and PCB pads 5, increases thermal resistance, so forms medium temperature height, edge
The low temperature gradient of temperature, makes weld tabs be melted in welding since center, effectively excludes gas, so that when reducing welding
Voidage.
Control experiment is carried out using QFN pads, gained voidage is respectively：Use tin cream for 54%, using plane weld tabs
For 23%, the voidage of the present embodiment is 6%, well below the voidage of tin cream and plane weld tabs.
Embodiment 3：
As shown in Figure 7 and Figure 8, a kind of preformed soldering, is the rectangular sheet of a 10mmx5mm, material Pb-5Sn-
2.5Ag.The section of its length direction is shuttle-type, the thickness 0.2mm at weld tabs center 11,12 thickness 0.08mm of weld tabs edge, weld tabs
Center 11 passes through straight transitions to weld tabs edge 12.
Control experiment is carried out using QFN pads, gained voidage is respectively：The voidage of tin cream is used as 34%, using flat
The voidage 18% of face weld tabs, the voidage of the present embodiment is 9%, less than the voidage of tin cream and plane weld tabs.
Embodiment 4：
As shown in Figure 9 and Figure 10, a kind of preformed soldering, is the rectangular sheet of a 7mmx7mm, is one kind of embodiment 3
Improve.Nickel wire 6 is symmetrically inlaid with along weld tabs length direction, and a diameter of 0.1mm, the centre-to-centre spacing of nickel wire 6 is 3mm, the edge of nickel wire 6
Embedding depth is 0.06mm.Nickel wire 6 is inlayed, and is played the role of aiding in weld tabs center 11 to support, can be placed preformed soldering
It is more steady when on PCB pads, reduce due to being rocked caused by uneven thickness, improve stability during assembling.Due to nickel wire
It is tiny, the heat transfer structure of weld tabs entirety will not be destroyed, can still form medium temperature height, the low temperature gradient of lip temperature, makes
Weld tabs orientation fusing, effectively excludes gas, so that voidage when reducing welding.
Control experiment is carried out using QFN pads, the voidage of gained is respectively：Use tin cream for 38%, using face bonding
Piece for 22%, the voidage of the present embodiment is 10%, less than the voidage of tin cream and plane weld tabs.
Embodiment 5：
As shown in figure 11, a kind of preformed soldering, is the rectangular sheet of a 8mmx4mm, center thickness 0.2mm, and edge is thick
0.1mm is spent, is a kind of improvement of embodiment 1.Cross high temperature wires 7 are inlaid with the preformed soldering and are used as skeleton,
Enhancing assemble stable is played, reduces inclined effect.The high temperature wires 7 be diameter 0.14mm fine copper silk, weld tabs center
The depth of inlaying at place is 0.1mm.
Control experiment is carried out using QFN pads, the voidage of gained is respectively：Use tin cream for 47%, using face bonding
Piece for 15%, and the voidage of the present embodiment is 9%, well below the voidage of tin cream and plane weld tabs.
Above content is to combine specific preferred embodiment further detailed description of the utility model, it is impossible to
Assert that the specific implementation of the utility model is confined to these explanations.For the ordinary skill of the utility model technical field
For personnel, without departing from the concept of the premise utility, some simple deduction or replace can also be made, should all be regarded
To belong to the scope of protection of the utility model.
Claims (9)
- A kind of 1. preformed soldering, it is characterised in that：It includes weld tabs body, in the longitudinal direction, in the weld tabs body Heart thickness ratio edge thickness is big；To the edge of both sides, thickness is in continuous transition at the center of the weld tabs body.
- 2. preformed soldering according to claim 1, it is characterised in that：The center thickness of the weld tabs body is thick for edge 1.5-5 times of degree.
- 3. preformed soldering according to claim 2, it is characterised in that：The center thickness of the weld tabs body is thick for edge 2-3 times of degree.
- 4. preformed soldering according to claim 2, it is characterised in that：The center of the weld tabs body is to any side The thickness change at edge is the change of monotone decreasing.
- 5. preformed soldering according to claim 4, it is characterised in that：The center of the weld tabs body is central platform.
- 6. preformed soldering according to claim 4, it is characterised in that：On length direction or width, the weldering Piece body is inlaid with wire, and the fusing point of the wire is more than the fusing point of weld tabs body.
- 7. preformed soldering according to claim 6, it is characterised in that：The wire is copper wire, nickel wire or filamentary silver.
- 8. according to the preformed soldering described in claim 1 ~ 7 any one, it is characterised in that：The material of the weld tabs body is Tin alloy solder, metal solder or indalloy.
- 9. according to the preformed soldering described in claim 1 ~ 7 any one, it is characterised in that：The surface of the weld tabs body is pre- Apply fluxing agent layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720984762.9U CN207239482U (en) | 2017-08-08 | 2017-08-08 | A kind of preformed soldering |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720984762.9U CN207239482U (en) | 2017-08-08 | 2017-08-08 | A kind of preformed soldering |
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| Publication Number | Publication Date |
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| CN207239482U true CN207239482U (en) | 2018-04-17 |
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ID=61880593
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| Application Number | Title | Priority Date | Filing Date |
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| CN201720984762.9U Active CN207239482U (en) | 2017-08-08 | 2017-08-08 | A kind of preformed soldering |
Country Status (1)
| Country | Link |
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| CN (1) | CN207239482U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107309571A (en) * | 2017-08-08 | 2017-11-03 | 深圳市亿铖达工业有限公司 | A kind of preformed soldering |
| CN112456805A (en) * | 2021-01-05 | 2021-03-09 | 合肥邦诺科技有限公司 | Large-area preformed low-temperature glass soldering lug and preparation method thereof |
-
2017
- 2017-08-08 CN CN201720984762.9U patent/CN207239482U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107309571A (en) * | 2017-08-08 | 2017-11-03 | 深圳市亿铖达工业有限公司 | A kind of preformed soldering |
| CN112456805A (en) * | 2021-01-05 | 2021-03-09 | 合肥邦诺科技有限公司 | Large-area preformed low-temperature glass soldering lug and preparation method thereof |
| CN112456805B (en) * | 2021-01-05 | 2021-08-24 | 合肥邦诺科技有限公司 | Large-area preformed low-temperature glass soldering lug and preparation method thereof |
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