CN101553091B - Printed circuit board and process for promoting qualification rate of lead-free process - Google Patents
Printed circuit board and process for promoting qualification rate of lead-free process Download PDFInfo
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- CN101553091B CN101553091B CN2008100900989A CN200810090098A CN101553091B CN 101553091 B CN101553091 B CN 101553091B CN 2008100900989 A CN2008100900989 A CN 2008100900989A CN 200810090098 A CN200810090098 A CN 200810090098A CN 101553091 B CN101553091 B CN 101553091B
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Abstract
A printed circuit board and a process for promoting the qualification rate of a lead-free process are used for welding at least one electronic element. The printed circuit board comprises a substrate,a solder mask and a lead-free and tin-free paste, wherein at least one lead and at least one solder pad are formed on the surface of the substrate, a first end part, a welding part and a second end p art far away from the first end part are defined by the solder pad, and the first end part is connected with the lead; the solder mask is covered on the lead of the substrate and the surface of the first end part but not to the welding part and the second end part; and the lead-free and tin-free paste bonds the electronic element and the welding par after tin is melted. Because the solder mask covers a part of the solder pad, tin can be agglomerated on a part pin during tin melting in a tin furnace to strengthen the tin-eating efficiency of the electronic element and increase the tin amount.
Description
Technical field
The present invention relates to a kind of printed circuit board (PCB) and technology, particularly a kind of printed circuit board (PCB) and manufacturing process thereof that promotes the lead-free process qualification rate.
Background technology
Surface adhering technology (Surface Mount Technology; SMT) be mainly used in printed circuit board (PCB) (Printed Circuit Board; PCB) the electronic component adhesion process on.
Electronic component can be divided into ventilating hole element (Plated Through HoleComponent according to the external form manner of packing; PTHC) and surface adhering element (Surface Mount Device; SMD) two big types.Ventilating hole element has pin, and when being placed on circuit board when positive, thereby circuit board has corresponding jack to allow pin to pass through, in case can tin on the pin be fixed in back of circuit board during through the tin stove; As for surface adhering element then is to coat tin cream at the pin place on plane, circuit size position on the mating circuit plate, and pin promptly is fixed on the circuit board after the fusing of heating tin cream.
With the surface adhering element is example, and different process equipment is divided into point gum machine, stencil printer, part pick and place machine and reflow stove in regular turn, and each several part can link with transport tape usually; Point gum machine does not drop so that temporarily be fixed in the manufacture process at the location point glue of putting surface adhering element; Then, the pin print solder paste that paste solder printing chance alignment member will be soldered lets the part pick and place machine automatically surface adhering element is placed on correct welding position again; At last, after the heating of reflow stove, make tin cream melt, surface adhering element is just accomplished and is fixedly welded on the circuit board.
Wherein one of surface treatment of printed circuit board (PCB) is like spray tin (Hot Air Solder Leveling; Abbreviation HASL) handling employed is plumbous (proportion of composing of Sn/Pb the is 63/37) scolder of tin; For satisfy European Union " harmful substance use restriction instruction " (being called for short ROHS) standard forbidding products containing lead requirement, certainly will stop using plumbous spray tin and change and adopt lead-free surface treatment such as organic scolder solderability preservative (Organic Solder Preservative; Abbreviation OSP), change silver (Immersion Sliver; Abbreviation ImAg), change nickel gold (Electroless Nickle Immersion Gold is called for short ENIG), change tin (ImmersionTin; Abbreviation Im Sn), lead-free tin spray (Lead Free Hot Air Solder Leveling; Be called for short Pb Free) etc.
In addition; Reflow stove (RE-FLOW) is handled employed tin lead (proportion of composing of Sn/Pb the is 63/37) scolder that also belongs to; Also be the requirement of " harmful substance use restriction instruction " standard forbidding products containing lead of satisfying European Union, certainly will stop using tin-lead solder and change and adopt lead-free tin cream.
Consult Fig. 1; General printed circuit board (PCB) 9 has base material 93, and base material 93 has a plurality of pads (PAD) 931 and a plurality of lead 932, and has the welding resisting layer 930 that is covered on a plurality of leads 932 on base material 93 surfaces; If electronic component pin 92 is adhered on the pad 931 with lead-free tin cream (Lead-Free Solder) 91; Then because the characteristic of lead-free tin cream 91 has caused product percent of pass not good, its reason comprises:
1. lead-free tin cream 91 tension force are bigger, when melting tin, are not easy to extend on the whole copper foil of pad 932, cause pad 931 to form invalid Xi Qu of eating or generation naked copper or part welding material from the teeth outwards near lead 932 parts and stay in invalid pad.
2. the tin content of lead-free tin cream 91 lacks than original tin content that contains Pb-Sn paste behind molten tin, so also will cause identical paste solder printing amount behind molten tin, to coat fully on the whole copper foil of pad 931.
3. the former Pb-Sn paste fusing point that contains can reach 220 to 225 ℃ of high temperature (about 40 ℃ of the temperature difference) for about 183 ℃; And the fusing point of lead-free tin cream 91 can reach about 245 ℃ of high temperature (about 30 ℃ of the temperature difference) for about 217 ℃; But the encapsulation heatproof of general part is about 240 to 250 ℃; For avoiding the part temperature too high, can't reach with long-time high temperature and strengthen the effect that lead-free tin cream 91 molten tin extend to the whole copper foil of pad 931.
Thereby if the problem that adopts lead-free tin cream 91 is without suitable processing, and common tin quantity not sufficient will cause that to eat tin between part and Copper Foil bad, cause problems such as empty weldering, dry joint or short circuit to produce; In addition, circular pad and square pad are crossed nearly short circuit easily; Contact point between pad 931 and the lead 932 corrodes because of chemical flux is residual easily in technology and causes chronic broken string.
No. 93134260 application of TaiWan, China patent documentation provides a kind of method through directly on welding resisting layer, scraping; Make lead-free tin cream can cover the pad on the base material fully; Though have step with welding resisting layer covering substrates and part pad; But all show both sides and exposed pad opening that its welding resisting layer cover part is a pad by the accompanying drawing (like Figure 1A～Fig. 1 E of this application) of its prior art and the accompanying drawing (like Fig. 2 A～Fig. 2 C of this application) after the improvement, can know that this application is to make similar BGA (Ball GridArray; BGA) method of metallic contact; It has the step that tin cream is advanced into pad again; Purpose is to obtain surface lead-free tin cream uniformly, but when the actual welding electronic component, still can't avoid taking place because the tin cream amount can't be climbed the problem of the whole pad of tin fully behind the molten tin.
Summary of the invention
Therefore, the object of the invention is promptly providing a kind of printed circuit board (PCB) and manufacturing process thereof that promotes the lead-free process qualification rate.
So the printed circuit board (PCB) that the present invention promotes the lead-free process qualification rate supplies at least one electronic component of welding, this printed circuit board (PCB) comprises base material, anti-welding lacquer and lead-free tin cream.
This substrate surface forms at least one lead and at least one pad, and this pad defines first end, weld part reaches the second end away from this first end, and this first end connects this lead; This anti-welding lacquer be covered in this base material lead and this first end the surface but not as good as in this weld part and this second end; This lead-free tin cream makes this electronic component and this weld part be bonded to each other behind molten tin.
In the above-mentioned printed circuit board (PCB), this anti-welding lacquer is covered in the length of this first end can be between 4 to 6 mils.
In the above-mentioned printed circuit board (PCB), this lead-free tin cream can cover the anti-welding lacquer surface of this first end to this second end before not molten tin.
In the above-mentioned printed circuit board (PCB), the leading edge that this anti-welding lacquer is covered in this first end can roughly be indent arc or tangent line shape.
The manufacturing process of printed circuit board (PCB) provided by the invention comprises following step: step a; Base material is provided; The surface of this base material forms at least one lead and at least one pad; This pad defines first end, weld part reaches the second end away from this first end, and this first end connects this lead; Step b covers anti-welding coat with lacquer in the surface of the lead of this base material and this first end but not as good as in this weld part and this second end; And step c, use lead-free tin cream, behind molten tin, make the pin of electronic component and this weld part be bonded to each other.
In the manufacturing process of above-mentioned printed circuit board (PCB), this anti-welding lacquer is covered in the length of this first end can be between 4 to 6 mils.
In the manufacturing process of above-mentioned printed circuit board (PCB), this lead-free tin cream can cover the anti-welding lacquer surface of this first end to this second end before not molten tin.
In the manufacturing process of above-mentioned printed circuit board (PCB), the leading edge that this anti-welding lacquer is covered in this first end can roughly be indent arc or tangent line shape.
The present invention promotes printed circuit board (PCB) and the manufacturing process thereof of lead-free process qualification rate owing to be the end that covers pad with anti-welding lacquer; Not only prevent to eat the bad problem of tin but also increase the tin amount of the welding of component pins, be not easy to extend to the problem on the whole copper foil of pad when avoiding the molten tin of lead-free tin cream simultaneously.
Description of drawings
Fig. 1 is a schematic perspective view, explains that present printed circuit board (PCB) runs into invalid Xi Qu of eating of formation or generation naked copper on bond pad surface easily when using lead-free tin cream as scolder;
Fig. 2 A is a sketch map, explains that the present invention promotes first preferred embodiment of the printed circuit board (PCB) of lead-free process qualification rate, and the leading edge that its anti-welding lacquer is covered in first end roughly is tangent line shape;
Fig. 2 B is a sketch map, and the lead-free tin cream that first preferred embodiment is described covers the anti-welding lacquer surface of first end to the second end;
Fig. 3 A is a sketch map, explains that the present invention promotes second preferred embodiment of the printed circuit board (PCB) of lead-free process qualification rate, and the leading edge that its anti-welding lacquer is covered in first end roughly is the indent arc;
Fig. 3 B is a sketch map, and the lead-free tin cream that second preferred embodiment is described covers the anti-welding lacquer surface of first end to the second end;
Fig. 4 is a sketch map, explains that substrate surface forms at least one lead and at least one pad;
Fig. 5 is a sketch map, explains to cover anti-welding lacquer and use lead-free tin cream in substrate surface;
Fig. 6 is a sketch map, and the position that the pin of electronic component is placed in the weld part of corresponding pad is described; And
Fig. 7 is a sketch map, explains that lead-free tin cream just is bonded to each other the pin of electronic component and the weld part of this pad behind molten tin.
Wherein, description of reference numerals is following:
(prior art)
9 printed circuit board (PCB)s
91 lead-free tin creams
92 electronic component pins
93 base materials
931 pads
932 leads
(the present invention)
1,1 ' printed circuit board (PCB)
10 base materials
11,11 ' anti-welding lacquer
13,13 ' lead-free tin cream
21 leads
22 pads
220 weld parts
221,221 ' first end
222,222 ' the second end
3 electronic components
31 pins
Embodiment
Aforementioned and other technology contents, characteristics and effect in the detailed description that following cooperation is carried out preferred embodiment with reference to accompanying drawing, can clearly appear about the present invention.Before describing the present invention in detail, be noted that in following description similar elements is to represent with identical numbering.
Consult Fig. 2 A, the present invention promotes in first preferred embodiment of printed circuit board (PCB) of lead-free process qualification rate, and printed circuit board (PCB) 1 comprises base material 10, anti-welding lacquer (Solder Mask) 11; Base material 10 surfaces form at least one lead (Conductor Pattern) 21 and at least one pad 22, and pad 22 defines the first end 221 that connects lead 21, the second end 222 that weld part 220 reaches away from first end 221.
Consult Fig. 2 B, anti-welding lacquer 11 surfaces that cover first end 221 before the molten tin of lead-free tin cream 13 are to the second end 222, and can make that behind molten tin the pin 31 of electronic component 3 is bonded to each other with weld part 220.
Consult Fig. 3 A and 3B; Whole elements of second preferred embodiment of printed circuit board (PCB) that the present invention promotes the lead-free process qualification rate are identical with first preferred embodiment; And lead-free tin cream 13 ' before molten tin, also cover first end 221 ' anti-welding lacquer 11 ' surface to the second end 222 '; Unique different be second preferred embodiment printed circuit board (PCB) 1 ' anti-welding lacquer 11 ' be covered in first end 221 ' leading edge roughly be the indent arc; Can coincide each other with the arc that extends out of lead-free tin cream 13 ' after molten tin shrinks thus, and then prevent that printed circuit board (PCB) naked copper phenomenon from taking place.
The processing step that the present invention promotes qualification rate waits each figure to describe with Fig. 4 to Fig. 7 respectively.
Consult Fig. 4, base material 10 at first is provided, the surface of this base material 10 forms at least one lead 21 and at least one pad 22, and this pad 22 defines the first end 221 that connects lead 21, the second end 222 that weld part 220 reaches away from first end 221.
Consult Fig. 5, then, at the lead 21 of this base material 10 and the anti-welding lacquer 11 of surface coverage of first end 221, but too late in weld part 220 and the second end 222, and the length L that anti-welding lacquer 11 is covered in first end 221 is between 4 to 6 mils (mil); And use lead-free tin cream 13, this lead-free tin cream 13 covered first end 221 before molten tin as yet anti-welding lacquer 11 surfaces are to the second end 222.
Consult Fig. 6, then, the pin 31 of electronic component 3 is placed in the position of the weld part 220 of corresponding pad 22, and has this lead-free tin cream 13 between pin 31 and the pad 22.
Consult Fig. 7; At last; This lead-free tin cream 13 just is bonded to each other the pin 31 of electronic component 3 and the weld part 220 of this pad 22 behind molten tin, but because anti-welding lacquer 11 is covered in the surface of first end 221; Make lead-free tin cream 13 only bonding towards the pin 31 of electronic component 3; Factors such as the tension force owing to lead-free tin cream 13 is big again, tin content tin content behind molten tin is less make lead-free tin cream 13 molten tin just can extend to the whole copper foil that pad 22 is not covered by anti-welding lacquer 11, do not have the problem generation of naked weldering or the invalid Xi Qu of eating.
Conclude above-mentioned; The present invention promotes printed circuit board (PCB) and the technology of lead-free process qualification rate owing to be with anti-welding lacquer cover part pad 22; It is the first end 221 of pad 22; Thereby be not easy to extend to the problem on the whole copper foil of pad 22 when not only having avoided the molten tin of lead-free tin cream 13, can prevent that also the pin 31 that naked copper produced, improved electronic component 3 from eating the tin height, preventing that contact point between lead 21 and the pad 22 from corroding because of chemical solvent is residual easily cause chronic broken string problem in technology; Again because the first end 221 that anti-welding lacquer 11 covers pad 22 has fixing effect, the phenomenon that pad 22 comes off in the time of therefore also can effectively improving maintenance.
Yet the above is merely the preferred embodiments of the present invention, and when not limiting the scope that the present invention implements with this, the simple equivalent of promptly doing according to claim of the present invention and invention description generally changes and revises, and all still belongs in the scope of the present invention.
Claims (6)
1. a printed circuit board (PCB) supplies at least one electronic component of welding, and this printed circuit board (PCB) comprises:
Base material, its surface forms at least one lead and at least one pad, and this pad defines first end, weld part reaches the second end away from this first end, and this first end connects this lead;
Anti-welding lacquer, be covered in this base material lead and this first end the surface but not as good as in this weld part and this second end; And
Lead-free tin cream makes this electronic component and this weld part be bonded to each other behind molten tin; It is surperficial to this second end that wherein this lead-free tin cream covers the anti-welding lacquer of this first end before molten tin.
2. printed circuit board (PCB) according to claim 1, wherein this anti-welding lacquer be covered in this first end length between 4 to 6 mils.
3. printed circuit board (PCB) according to claim 1 and 2, wherein this anti-welding lacquer leading edge of being covered in this first end is indent arc or tangent line shape.
4. the manufacturing process of a printed circuit board (PCB) comprises following step:
Step a provides base material, and the surface of this base material forms at least one lead and at least one pad, and this pad defines first end, weld part reaches the second end away from this first end, and this first end connects this lead;
Step b covers anti-welding coat with lacquer in the surface of the lead of this base material and this first end but not as good as in this weld part and this second end; And
Step c uses lead-free tin cream, behind molten tin, makes the pin of electronic component and this weld part be bonded to each other; It is surperficial to this second end that wherein this lead-free tin cream covers the anti-welding lacquer of this first end before molten tin.
5. the manufacturing process of printed circuit board (PCB) according to claim 4, wherein this anti-welding lacquer be covered in this first end length between 4 to 6 mils.
6. according to the manufacturing process of claim 4 or 5 described printed circuit board (PCB)s, wherein this anti-welding lacquer leading edge of being covered in this first end is indent arc or tangent line shape.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008100900989A CN101553091B (en) | 2008-04-02 | 2008-04-02 | Printed circuit board and process for promoting qualification rate of lead-free process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008100900989A CN101553091B (en) | 2008-04-02 | 2008-04-02 | Printed circuit board and process for promoting qualification rate of lead-free process |
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| Publication Number | Publication Date |
|---|---|
| CN101553091A CN101553091A (en) | 2009-10-07 |
| CN101553091B true CN101553091B (en) | 2012-07-04 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2008100900989A Active CN101553091B (en) | 2008-04-02 | 2008-04-02 | Printed circuit board and process for promoting qualification rate of lead-free process |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102088822B (en) * | 2009-12-08 | 2014-12-17 | 三星半导体(中国)研究开发有限公司 | PCB (printed circuit board) substrate with welding spot self-protection function and manufacturing process of pad of PCB substrate |
| CN106229712A (en) * | 2016-08-25 | 2016-12-14 | 歌尔股份有限公司 | Adapter encapsulating structure and electronic equipment |
| CN107038964A (en) * | 2017-03-02 | 2017-08-11 | 利亚德电视技术有限公司 | LED display module and its assembly method and LED display |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1281256A (en) * | 1999-07-20 | 2001-01-24 | 三星电子株式会社 | Welding pad structure for semi-conductor package |
| US6295709B1 (en) * | 1995-11-30 | 2001-10-02 | Micron Technology, Inc. | Printed circuit board assembly and method for making a printed circuit board assembly |
| JP2002141660A (en) * | 2000-10-31 | 2002-05-17 | Fujikura Ltd | Method for connecting flexible printed board to each other |
| CN1852638A (en) * | 2006-01-24 | 2006-10-25 | 华为技术有限公司 | Printing welding-paste method and printing tin steel-screen |
| CN1996587A (en) * | 2006-01-06 | 2007-07-11 | 松下电器产业株式会社 | Circuit board, method for manufacturing the same, semiconductor device, and method for manufacturing the same |
-
2008
- 2008-04-02 CN CN2008100900989A patent/CN101553091B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6295709B1 (en) * | 1995-11-30 | 2001-10-02 | Micron Technology, Inc. | Printed circuit board assembly and method for making a printed circuit board assembly |
| CN1281256A (en) * | 1999-07-20 | 2001-01-24 | 三星电子株式会社 | Welding pad structure for semi-conductor package |
| JP2002141660A (en) * | 2000-10-31 | 2002-05-17 | Fujikura Ltd | Method for connecting flexible printed board to each other |
| CN1996587A (en) * | 2006-01-06 | 2007-07-11 | 松下电器产业株式会社 | Circuit board, method for manufacturing the same, semiconductor device, and method for manufacturing the same |
| CN1852638A (en) * | 2006-01-24 | 2006-10-25 | 华为技术有限公司 | Printing welding-paste method and printing tin steel-screen |
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| Publication number | Publication date |
|---|---|
| CN101553091A (en) | 2009-10-07 |
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Owner name: MSI COMPUTER SHENZHEN CO., LTD. Free format text: FORMER OWNER: WEIXING SCIENCE + TECHNOLOGY CO., LTD. Effective date: 20120426 |
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