CN110784999A

CN110784999A - PCB manufacturing method, PCBA manufacturing method, PCB and SMT template

Info

Publication number: CN110784999A
Application number: CN201911036103.2A
Authority: CN
Inventors: 何宗明; 贾首锋
Original assignee: Shenzhen Fastprint Circuit Tech Co Ltd; Yixing Silicon Valley Electronic Technology Co Ltd
Current assignee: Shenzhen Fastprint Circuit Tech Co Ltd; Guangzhou Fastprint Circuit Technology Co Ltd; Yixing Silicon Valley Electronic Technology Co Ltd
Priority date: 2019-10-29
Filing date: 2019-10-29
Publication date: 2020-02-11

Abstract

Compared with the mode that the whole window is opened at the joint of the shielding cover and the PCB in the prior art, the PCB manufacturing method, the PCBA manufacturing method, the PCB and the SMT template provided by the invention cover the through hole arranged in the joint area of the shielding cover and the PCB, prevent the through hole from being oxidized and improve the product quality. Divide into windowing district and non-windowing district with shield cover and PCB junction, reduce the welding degree of difficulty of shield cover, promote production efficiency. After the shielding cover is welded with the PCB, compared with the mode of integrally windowing in the prior art, the shielding effect is basically consistent, and other costs are not required to be increased.

Description

PCB manufacturing method, PCBA manufacturing method, PCB and SMT template

Technical Field

The invention relates to the technical field of PCB manufacturing, in particular to a PCB manufacturing method, a PCBA manufacturing method, a PCB and an SMT template.

Background

Shielding is one means in electrical engineering. In order to prevent interference of external electric, magnetic or electromagnetic fields with the internal devices or to avoid influence of the electromagnetic fields of the devices on the outside, the devices are placed in a closed or nearly closed metal shell or mesh enclosure, which is referred to as a shield. In some PCB (Printed Circuit Board) cards, a shielding can is used to electromagnetically shield the Circuit modules on the card. The PCB Board is called PCBA (Printed Circuit Board + Assembly) after mounting various components including the shield can, and when the shield can is soldered to the PCB in a patch manner, as shown in fig. 1, an integral windowing region 121 is formed at a position on the PCB where the shield can is soldered. Due to the fact that the ground through hole needs to be drilled at the joint of the shielding case and the PCB, the through hole needs to be subjected to windowing processing, and the through hole is prone to being oxidized. Meanwhile, the whole window opening also causes the welding difficulty of the shielding case and influences the processing efficiency.

Disclosure of Invention

Based on this, it is necessary to provide a PCB manufacturing method, a PCBA manufacturing method, a PCB and an SMT template, aiming at the problem that the current PCB has a via hole oxidation due to the window at the position for mounting the shield can.

The above purpose is realized by the following technical scheme:

a PCB manufacturing method comprises the following steps:

s10, according to the shape and the size of the shielding case, a welding area and a mounting area are defined on the PCB of the manufactured circuit, and the welding area surrounds the mounting area; the welding area is used for welding shielding devices, and the mounting area is used for mounting components;

s20, manufacturing a plurality of through holes in the welding area;

s30, forming a non-windowed area covered by the ink/covering layer and a non-covered windowed area in the welding area; the non-windowed area covers the via hole.

In one embodiment, the windowed area and the non-windowed area are staggered.

In one embodiment, the mounting area is a rectangular area, and the windowed area or the non-windowed area is inclined to the length direction of the rectangular area.

In one embodiment, the angle between the windowed area and the length direction of the rectangular area is 30-60 °.

In one embodiment, the bonding area is used for mounting a shielding case, and the width of the bonding area is equal to the thickness of the wall of the shielding case.

In one embodiment, the width of the windowing area is 15-25 mil, and the minimum distance between two adjacent windowing areas is 15-25 mil.

The invention also provides a PCBA manufacturing method, which comprises the following steps:

s20, manufacturing a plurality of through holes in the welding area;

s30, forming a non-windowed area covered by the ink/covering layer and a non-covered windowed area in the welding area; the non-windowing region covers the via hole;

and S40, brushing the flux on the windowing area, and welding the shielding case.

In one embodiment, the flux painting in step S50 is performed by using an SMT stencil having a window formed therein, and the window is matched with the shape of the windowing region.

The present invention also provides a PCB including: the mounting area is used for mounting components, the welding area is used for mounting a shielding case, and the welding area surrounds the mounting area; the welding area is divided into a windowing area and a non-windowing area, and a plurality of through holes are formed in the non-windowing area.

In one embodiment, the windowed area and the non-windowed area are staggered.

The present invention also provides an SMT stencil having a plurality of windows formed therein, the windows having the same or similar shape as the windowing regions according to any of claims 1-6.

In one embodiment, the window size is smaller than the windowing region size.

The invention has the beneficial effects that:

Drawings

FIG. 1 is a schematic diagram of a partial structure of a PCB board using an integral windowing method in the prior art;

FIG. 2 is a schematic diagram of a PCB provided in an embodiment of the invention;

FIG. 3 is a schematic structural diagram of a PCB and an SMT stencil according to an embodiment of the invention after being stacked;

fig. 4 is a schematic diagram of a PCB and an SMT stencil stacked and provided with through holes according to an embodiment of the present invention.

Wherein:

a PCB (100); a mounting area 110; a welding region 120; a windowing region 121; a non-windowed region 122; a via 123; the width A of the windowing area; a non-windowed area width B; a window 200.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below by way of embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The numbering of the components themselves, such as "first", "second", etc., is used herein only to distinguish between the objects depicted and not to have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings). In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

The present invention provides a PCB100, as shown in fig. 4, including a mounting area 110 and a bonding area 120, wherein the mounting area 110 is used for mounting components, the bonding area 120 is used for mounting a shielding can, and the bonding area 120 surrounds the mounting area 110; the bonding pad 120 is divided into a windowing region 121 and a non-windowing region 122, and a plurality of vias 123 are formed in the non-windowing region 122. Since the chip or other electrical components need to be electromagnetically isolated from the PCB or the external environment, a shielding can is usually coated outside the chip; in order to achieve better shielding effect, a plurality of vias 123 (or ground holes, over ground holes, and ground holes) need to be drilled on the portion of the PCB contacting the shielding can. Since the shield can needs to be fixed on the PCB by soldering, the whole window needs to be opened in the contact area between the PCB and the shield can, so that the metal surface is exposed for soldering. This leaves the via 123 exposed after drilling, which tends to oxidize the via 123. The PCB100 provided by the invention is windowed at intervals, windowing is not carried out at the position of the via hole 123, and the via hole 123 is covered with ink, so that the oxidation of the via hole 123 can be avoided, the problem of welding difficulty during welding of the shielding case due to integral windowing is avoided, and the product quality and the processing efficiency are improved.

In some embodiments, as shown in FIG. 2, the windowed sections 121 and non-windowed sections 122 are staggered to form a structure similar to a grid. When the shielding cover is arranged in a staggered mode, the shielding cover is welded with a metal surface in the windowing area 121 on the PCB, but the non-windowing area 122 is not welded with the shielding cover due to the fact that ink or a covering layer covers the shielding cover, so that welding points between the shielding cover and the PCB are distributed at intervals uniformly relatively, and compared with a full-open window, the welding effect is basically consistent. Further, since the entire window is opened, flux such as solder paste may flow during thermal fusion bonding, which may cause a bonding defect. With windowing district 121 and non-windowing district 122 interval setting for the welding flux is under the hindrance of non-windowing district 122, relatively fixed in windowing district 121, reduces the welding degree of difficulty, promotes welding quality, improves machining efficiency.

Further, for example, the mounting area 110 is rectangular, in order to improve the shielding effect, the non-windowed area 122 is disposed obliquely to the length direction of the mounting area 110, and correspondingly, the plurality of vias 123 are also disposed obliquely to the length direction of the mounting area 110. Therefore, compared with the plurality of via holes 123 arranged in a rectangular shape, the shielding structure formed by the staggered arrangement of the plurality of via holes 123 has a better shielding effect, which is basically consistent with the shielding effect during the integral windowing, and does not increase other costs. It will be appreciated that the shield is typically of a more regular rectilinear shape, and for other shapes of mounting region 110, the non-windowed region 122 could equally be disposed obliquely to one side of the mounting region 110, such that the plurality of apertures could be staggered.

In some embodiments, the fenestration area 121 is angled 30-60 from a side of the mounting area 110.

In some embodiments, the width of the fenestration areas 121 is 15-25 mil (mil, mil-inch, 1 mil-0.0254 mm), and the minimum distance between two adjacent fenestration areas 121 is 15-25 mil.

The present invention also provides an SMT (Surface mount Technology) stencil, as shown in fig. 3, for soldering a shield can to a PCB in the above-described embodiment. The SMT stencil is provided with a plurality of windows 200, solder pastes and other welding fluxes in a flowing state are adhered to the surface of the PCB through the windows 200, and have a relatively correct position relation with the surface of the PCB. The window 200 of the SMT stencil may have the same shape, position, and size or similar to the fenestration area 121 of the PCB100 of the previous embodiment, so that solder paste can fall from the window 200 onto the PCB and be soldered to the shield can during the SMT process.

In some of these embodiments, as shown in FIG. 3, the window 200 is sized smaller than the windowed area 121. In the SMT printing process, after the SMT stencil and the PCB are aligned, the window 200 of the stencil is completely located in the windowing region 121 of the PCB, so that the solder flux falls on the metal surface of the windowing region 121, and does not fall on the boundary between the windowing region 121 and the non-windowing region 122 or on the ink/coating of the non-windowing region 122. Since the ink/cover layer is usually an insulating organic material, the solder is difficult to solder with the insulating organic material, and if the solder falls on the non-windowed area 122 or the boundary between the windowed area 121 and the non-windowed area 122, firstly, poor soldering effect is easily caused, and secondly, the ink/cover layer is easily damaged. Therefore, the SMT stencil window 200 is designed to be inwardly shrunk according to the size of the PCB windowing area 121, and the welding defects are avoided.

In some embodiments, the SMT stencil is a stainless steel stencil, a surface nickel plated stencil or a high polymer stencil. In most cases, stainless steel templates are adopted, and the stainless steel templates have good comprehensive performance and relatively low manufacturing cost. Compared with a stainless steel template, the nickel-plated template has the advantages that the surface is smoother, the smoothness and the precision of the opening are good, the machining performance is better, the thickness of the stainless steel template can be only machined to be 0.07mm under the common condition, and the thickness of the nickel-plated template can be machined to be 0.03 mm. The high polymer template has better processing precision, but has higher requirements on the processing capacity, higher cost and shorter service life.

The invention also provides a PCB manufacturing method, wherein the PCB is provided with the shielding cover in an attached manner, and the PCB manufacturing method is characterized by comprising the following steps of:

s20, manufacturing a plurality of through holes in the welding area;

The shapes of the windowing region and the non-windowing region in step S30 are the same as those of the windowing region and the non-windowing region in the PCB in the previous embodiment. In step S30, when printing ink, a layer of liquid ink is first applied on the whole PCB, and then the ink is cured in the irradiated area by ultraviolet irradiation, so that the ink in the uncured area can form an area covered by the ink and an area not covered by the ink, i.e. the non-windowed area and the windowed area in the above embodiment.

The invention also provides a manufacturing method of the PCBA, which comprises the following steps:

s20, manufacturing a plurality of through holes in the welding area;

Further, the flux painting in step S40 is performed by using an SMT stencil, the SMT stencil is provided with a window, and the flux in a flowing state falls into the window during the painting and adheres to the surface of the PCB; the window is the same shape as the window in the SMT stencil in the previous embodiment.

Compared with the prior art, the PCB manufacturing method, the PCBA manufacturing method, the PCB and the SMT template provided by the invention at least have the following advantages:

1. compared with the mode that the whole window of shield cover and PCB junction is compared among the prior art, be equipped with the hole department in the middle of shield cover and the PCB connected region and cover, prevent that the via hole from being by oxidation, promote the product quality.

2. Divide into windowing district and non-windowing district with shield cover and PCB junction, reduce the welding degree of difficulty of shield cover, promote production efficiency.

3. After the shielding cover is welded with the PCB, compared with the mode of integrally windowing in the prior art, the shielding effect is basically consistent, and other costs are not required to be increased.

The first embodiment is as follows:

as shown in fig. 4, the present embodiment provides a PCB on which a mounting area 110 for mounting a component and a land 120 for mounting a shield can are disposed, the land 120 including a windowed area 121 and a non-windowed area 122, a plurality of vias 123 disposed in the non-windowed area 122, the vias 123 being covered by an ink/overcoat layer.

The mounting area 110 is a rectangular area, the land 120 is a rectangular frame area, and the land 120 completely surrounds the mounting area 110. The center line of the mounting region 110 in the transverse direction is the X direction, and the center line of the mounting region 110 in the longitudinal direction is the Y direction. The soldering region 120 is formed as a rectangular frame having a width equal to the thickness of the shield can, and the soldering region 120 has an overall length and width equal to the length and width of the mounting region 110 plus twice the thickness of the shield can, respectively.

The fenestration areas 121 and the non-fenestration areas 122 are spaced apart to form a structure similar to a grid. The windowing region 121 and the non-windowing region 122 are both arranged in an inclined manner relative to the X direction or the Y direction, the inclination angle is 45 degrees, the windowing region 121 is in the shape of an isosceles trapezoid or a parallelogram, the width a of the windowing region 121 is about 20mil, and the minimum distance between two adjacent windowing regions 121 is also about 20 mil.

Example two:

the embodiment provides a manufacturing method of a PCBA (printed circuit board assembly) with a shielding case, which comprises the following steps:

s20, manufacturing a plurality of through holes in the welding area;

s30, printing ink/blanket;

s40, removing the redundant ink/covering layer, and forming a non-windowing area covered by the ink/covering layer and an uncovered windowing area in the welding area; the non-windowing region covers the via hole;

and S50, brushing the flux on the windowing area, and welding the shielding case.

Due to the limitation of the processing capability, in the manufacturing process of the PCB, each component has a certain error with the design position, the processing error is controlled within a preset range under the normal condition, and after the whole PCB production flow is finished, the deviation between each component and the design position does not exceed the preset value.

For the present embodiment, the via hole needs to be located in the non-windowing region and covered by the ink, the distance between the via hole and the windowing region needs to be controlled, the process error is set to 4 mils by the calculation of the existing process capability, and the width a of the windowing region and the width B of the non-windowing region are designed according to the design and then trial-run is performed. And if the trial result is qualified, the mass production can be carried out, and if the trial result is not qualified, the sizes of the A and the B are adjusted, so that the via hole cannot be positioned in the windowing area and exposed in the process capacity range, and the via hole is oxidized.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A PCB manufacturing method is characterized by comprising the following steps:

s20, manufacturing a plurality of through holes in the welding area;

2. The method of claim 1, wherein the windowed areas and non-windowed areas are staggered.

3. The method of claim 2, wherein the mounting area is a rectangular area, and the windowed area or the non-windowed area is tilted with respect to a length direction of the rectangular area.

4. A method of fabricating a PCB as claimed in claim 3, wherein the angle between the windowed area and the length direction of the rectangular area is 30 ° to 60 °.

5. The method of claim 3, wherein the bonding pad is configured to receive a shield can, and the bonding pad has a width equal to a thickness of the shield can.

6. The method for manufacturing a PCB of any of claims 1-5, wherein the width of the windowing areas is 15-25 mil, and the minimum distance between two adjacent windowing areas is 15-25 mil.

7. A PCBA manufacturing method is characterized by comprising the following steps:

s20, manufacturing a plurality of through holes in the welding area;

8. The method of manufacturing a PCBA as recited in claim 7, wherein the flux brushing in step S50 is performed using an SMT stencil having a window formed therein, the window matching the shape of the fenestrated area.

9. A PCB, comprising: the mounting area is used for mounting components, the welding area is used for mounting a shielding case, and the welding area surrounds the mounting area; the welding area is divided into a windowing area and a non-windowing area, and a plurality of through holes are formed in the non-windowing area.

10. An SMT stencil having a plurality of windows of the same or similar shape as said windowed area of any of claims 1-6, said windows being smaller in size than said windowed area.