CN201319699Y - Tinning steel mesh for surface attachment of ball grid array structure integrated circuits - Google Patents
Tinning steel mesh for surface attachment of ball grid array structure integrated circuits Download PDFInfo
- Publication number
- CN201319699Y CN201319699Y CNU2008202139767U CN200820213976U CN201319699Y CN 201319699 Y CN201319699 Y CN 201319699Y CN U2008202139767 U CNU2008202139767 U CN U2008202139767U CN 200820213976 U CN200820213976 U CN 200820213976U CN 201319699 Y CN201319699 Y CN 201319699Y
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- CN
- China
- Prior art keywords
- bonding pad
- pad hole
- ball grid
- array structure
- grid array
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Abstract
The utility model discloses a tinning steel mesh for the surface attachment of ball grid array structure integrated circuits (BGA). The tinning steel mesh is provided with a square chamfered bonding pad hole; the diameter of the inscribed circle of the regular hexagon is the diameter of a ball grid; the bonding pad hole adopts the chamfered square, and the characteristic of stress concentrated at the edges is utilized to reduce the plugging of the bonding pad hole. The diameter of the inscribed circle of the bonding pad hole is equal to the diameter of the bonding pad, only very little of soldering paste is coated outside the bonding pad in printing and can be molten and reflow to the bonding pad when passing through a reflow oven, thus avoiding the bridge connection between ball grids.
Description
[technical field]
The utility model relates to tin paste printed steel mesh in a kind of surface mount process, especially relates to a kind of seal tin steel-screen that is used for ball grid array structure (BGA) integrated circuit surface mounting.
[background technology]
In the integrated circuit encapsulation, often use ball grid array structure (BGA) integrated circuit encapsulation technology.Adopt the chip of this encapsulation technology, ball bar is pin.With chip attachment before the printed circuit board (PCB), need on the pad of ball bar, smear tin cream.Mode now commonly used is 100% to carry out perforate according to the shape of pad on the seal tin steel-screen, and the shape in hole is consistent with bond pad shapes, is circle.Then steel mesh is covered on the pad, utilize the scraper on the printing machine again, the tin cream on the steel mesh is filled in the perforate of steel mesh.After removing, steel mesh just stayed the tin cream consistent on the pad with bond pad shapes.
The problem that exists is now: in printing process, temporarily stop printing through regular meeting because of replacing material or adjustment machinery equipment.Because the area of ball bar is very little, the area in pad hole is consistent with ball bar, and is also very little, in the process of printing, can adhere to some tin creams inevitably in the pad hole.In the time period of suspending printing, this part tin cream that sticks in the pad hole is understood the comparison drying because water evaporates becomes.When restarting to print, the part tin cream is not easy to break away from the pad hole, makes the pad hole plug, and tin is not enough on the pad, causes empty weldering when welding, produces defective products.
[utility model content]
In view of this, be necessary to provide a kind of seal tin steel-screen that can effectively prevent the pad hole plug.
In order to solve the problems of the technologies described above, by the following technical solutions:
A kind of seal tin steel-screen that is used for the ball grid array structure integrated circuit surface mounting offers the pad hole on it, described pad hole is a square.
Further: the diameter that described foursquare inscribe diameter of a circle is a ball bar.
Further: described square is chamfering on four angles.
Further: the leg-of-mutton height that described square chamfering is removed is described square vertices to 1/3 of the distance of described inscribed circle.
Square is adopted in the pad hole of above-mentioned seal tin steel-screen, and the characteristics that can utilize edge's stress to concentrate reduce pad hole choking phenomenon.
The inscribe diameter of a circle in the pad hole of above-mentioned seal tin steel-screen equals the diameter of pad, and the tin cream during printing has only few part to spread upon outside the pad, can melt to be back to pad when crossing reflow ovens, avoids bridge joint between the ball bar.
[description of drawings]
Fig. 1 is the schematic diagram of seal tin steel-screen
Fig. 2 is the pad hole schematic diagram of seal tin steel-screen
Wherein:
10-seal tin steel-screen 120-pad hole
Be further detailed below in conjunction with accompanying drawing.
[embodiment]
IPC7525 opens the steel mesh standard and only the size of pitch spacing (spacing of adjacent ball bar central point) more than or equal to pad hole under the 0.5mm is defined.Often use the thin space ball grid array structure of pitch spacing on the pcb board of the product of communication class such as mobile phone, bluetooth less than 0.5mm.Because pitch is apart from less than 0.5mm, ball bar, just phase of solder joint is to also very little, if perforate is carried out in strict accordance with the size of ball bar in the pad hole, the situation of pad hole plug can be more serious, therefore needs suitably to increase tin amount down.
Following examples are improved the seal tin steel-screen of integrated circuit surface mounting under this kind situation.
Suppose the ball bar pad for circular, diameter is D.As shown in Figure 1, offer pad hole 120 on the seal tin steel-screen 100, pad hole 120 is a square.
As shown in Figure 2, the inscribed circle in pad hole 120 is the D of diameter.When printing process suspends for some reason, also can be stained with tin cream in the square pad hole 120.Time out acquires a certain degree, and as half an hour, it is comparatively dry that this part tin cream can become.When restarting to print, because pad hole 120 is hexagons, the stress of edge is concentrated the pad hole that is greater than circular edge, under the effect of scraper strength, the comparatively dry tin cream ratio that adheres in the pad hole 120 is easier to come off from pad hole 120, has solved pad hole 120 blocking problem preferably.
As shown in Figure 2, pad hole 120 is preferably in place, four angles chamfering, can increase stress concentration point, increases the resistance point to scraper, promotes that tin cream comes off.Experiment shows, the leg-of-mutton height that chamfering is removed be square vertices to the inscribed circle distance 1/3 the time can reduce the phenomenon of few weldering to greatest extent.Suppose that foursquare catercorner length is L, the leg-of-mutton height H of being cut away=(L-D)/6.
Adopt the pad hole 120 of this mode, in the process of normal printing, the following tin amount in the circular pad hole that following tin amount ratio employing diameter is D is slightly bigger.This part many slightly tin cream amount is positioned at foursquare corner, has spread upon on the surface-mounted integrated circuit.The material of surface-mounted integrated circuit is not adhere to tin cream.When crossing reflow ovens, this part tin cream can melt and is back on the circular pad under action of high temperature, avoids bridge joint between the ball bar.
If adopt the pad hole 120 of other shapes, as diameter is the circumscribed regular hexagon of the circle of D, tin amount is less than the following tin amount of present embodiment under it, the few tin phenomenon that can not eliminate generation well is (in the pitch spacing during less than 0.5mm, because the size in pad hole 120 is correspondingly little, unavoidably have the situation of a little obstruction).If adopt the pad hole of other areas, can cause occurring between the ball bar bridge joint owing to following tin amount is excessive again greater than present embodiment.
The above embodiment has only expressed several execution mode of the present utility model, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to the utility model claim.Should be pointed out that for the person of ordinary skill of the art under the prerequisite that does not break away from the utility model design, can also make some distortion and improvement, these all belong to protection range of the present utility model.Therefore, the protection range of the utility model patent should be as the criterion with claims.
Claims (4)
1. a seal tin steel-screen that is used for the ball grid array structure integrated circuit surface mounting offers the pad hole on it, it is characterized in that: described pad hole is square.
2. the seal tin steel-screen that is used for the ball grid array structure integrated circuit surface mounting as claimed in claim 1 is characterized in that: the diameter that described foursquare inscribe diameter of a circle is a ball bar.
3. the seal tin steel-screen that is used for the ball grid array structure integrated circuit surface mounting as claimed in claim 2 is characterized in that: described square is chamfering on four angles.
4. the seal tin steel-screen that is used for the ball grid array structure integrated circuit surface mounting as claimed in claim 3 is characterized in that: the leg-of-mutton height that described square chamfering is removed is described square vertices to 1/3 of the distance of described inscribed circle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008202139767U CN201319699Y (en) | 2008-11-28 | 2008-11-28 | Tinning steel mesh for surface attachment of ball grid array structure integrated circuits |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008202139767U CN201319699Y (en) | 2008-11-28 | 2008-11-28 | Tinning steel mesh for surface attachment of ball grid array structure integrated circuits |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201319699Y true CN201319699Y (en) | 2009-09-30 |
Family
ID=41198456
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNU2008202139767U Expired - Fee Related CN201319699Y (en) | 2008-11-28 | 2008-11-28 | Tinning steel mesh for surface attachment of ball grid array structure integrated circuits |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201319699Y (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102843857A (en) * | 2011-06-24 | 2012-12-26 | 发那科株式会社 | Printed wiring board with lands |
| CN105813401A (en) * | 2016-05-16 | 2016-07-27 | 浪潮电子信息产业股份有限公司 | SMT stencil windowing design method for VGA connector |
| CN108447837A (en) * | 2017-02-16 | 2018-08-24 | 中芯国际集成电路制造(上海)有限公司 | A kind of semiconductor devices |
-
2008
- 2008-11-28 CN CNU2008202139767U patent/CN201319699Y/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102843857A (en) * | 2011-06-24 | 2012-12-26 | 发那科株式会社 | Printed wiring board with lands |
| US20120325543A1 (en) * | 2011-06-24 | 2012-12-27 | Fanuc Corporation | Printed wiring board (pwb) with lands |
| CN102843857B (en) * | 2011-06-24 | 2013-07-03 | 发那科株式会社 | Printed wiring board with pads |
| US8847083B2 (en) * | 2011-06-24 | 2014-09-30 | Fanuc Corporation | Printed wiring board (PWB) with lands |
| CN105813401A (en) * | 2016-05-16 | 2016-07-27 | 浪潮电子信息产业股份有限公司 | SMT stencil windowing design method for VGA connector |
| CN105813401B (en) * | 2016-05-16 | 2018-07-24 | 浪潮电子信息产业股份有限公司 | A kind of SMT steel meshes windowing design method of VGA connector |
| CN108447837A (en) * | 2017-02-16 | 2018-08-24 | 中芯国际集成电路制造(上海)有限公司 | A kind of semiconductor devices |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20090930 Termination date: 20141128 |
|
| EXPY | Termination of patent right or utility model |