CN109109481A - A kind of printing process of tin cream - Google Patents

Abstract

The present invention provides a kind of printing process of tin cream, and preparation method is specially to provide a printed circuit board, has the first pad area, the second pad area and non-pad area on the upper surface of printed circuit board, print solder paste thickness needed for the first pad area is greater than the second pad area；The first solder mask is prepared on non-pad area；The second solder mask is prepared on the first solder mask；The second solder mask removed around the second pad area forms the first Printing Zone；Cover steel mesh；Tin cream is applied on steel mesh, scraper is in steel online mobile, by deforming when the first Printing Zone and being close to the first solder mask, it presses scraper tin cream and passes through steel mesh coated on the first pad area, the second pad area, to lower recess around second pad area and the second pad area, the thickness for the tin cream for being covered on the second pad area is made to be less than the thickness for being covered on the tin cream of the first pad area；Steel mesh is removed, the different tin cream of thickness is finally made in same printed circuit board.

Description

A kind of printing process of tin cream

Technical field

The present invention relates to printed circuit board packaging technology more particularly to a kind of printing processes of tin cream.

Background technique

During manufacturing electronic product, need that various components are welded to printing using surface mounting technology (SMT)On circuit board, more common surface mount process process are as follows: exist first in the one side that printed circuit board needs to mount componentThe position coating tin cream for needing to mount component, then will need the component welded to be attached to the corresponding position of printed circuit board againOn, reflow soldering is carried out after completing the attachment of component, this completes the printed circuit board wherein attachment of upper component on one side,Through surface mount can be completed after the assay was approved.

Steel mesh is a kind of surface mounting technology particular manufacturing craft, and major function is to aid in the deposition of tin cream, it is therefore an objective to will be quasi-The tin cream of exact figures amount is transferred to the position of the correspondence pad in printed wiring board.Since different components are welded to tin cream thicknessDemand is different, often will use ladder steel mesh, the thickness of the different zones steel disc on the ladder steel mesh in the process of paste solder printingDegree is different, so the thickness of tin cream is not also identical on last pad.

But ladder steel mesh complex manufacturing technology, and it is at high cost；Printing effect is bad, if the area in the thin region of ladder steel meshIt is too small, it will result in the phenomenon that this region is easy to appear tin cream residual.

Summary of the invention

The technical problem to be solved in the present invention is to provide paste solder printings a kind of at low cost and with preferable printing effectMethod.

In order to solve the above technical problems, the present invention adopts the following technical solutions: a kind of printing process of tin cream is used forPrint solder paste in printed circuit board assembling process, comprising the following steps:

(1) printed circuit board is provided, there is the first pad area, the second pad area on the upper surface of the printed circuit boardAnd non-pad area, print solder paste thickness needed for first pad area are greater than second pad area；

(2) the first solder mask is prepared on the non-pad area；

(3) the second solder mask is prepared on first solder mask；

(4) the second solder mask removed around the second pad area forms the first Printing Zone；

(5) one layer of steel mesh is covered on second solder mask；

(6) tin cream is applied on the steel mesh, using scraper in the steel online mobile, the scraper is by the first printingThe steel mesh deformation sinks and is close to first solder mask when area, and pressing the scraper makes the tin cream on the steel mesh pass through instituteSteel mesh is stated coated on first pad area, on second pad area, second pad area and second pad areaSurrounding makes the thickness for the tin cream for being covered on second pad area be less than the tin cream for being covered on first pad area to lower recessThickness；

(7) steel mesh is removed.

Design concept according to the present invention, steel mesh of the present invention further include ontology and the positioning for being set to outer bodyFrame positions the steel mesh by the posting.

Design concept according to the present invention, in step S5 of the present invention, the steel mesh includes through the of the ontologyOne printing hole and the second printing hole, first printing hole and second printing hole and first pad area and described secondThe position of pad area and size are corresponding.

Design concept according to the present invention, in step S2 of the present invention, described in first solder mask and step S3Second solder mask under ultraviolet excitation, is cross-linked into solid-state and is prepared by the welding resistance oil of liquid.

Design concept according to the present invention, welding resistance oil of the present invention include epoxy resin, emulsion, solvent, fillerAnd pigment.

Design concept according to the present invention, a length of 365nm of the ultraviolet light wave of ultraviolet irradiation of the present invention, power be 5~10W。

Design concept according to the present invention, in step S6 of the present invention, the angle of scraper and steel mesh is 45~60 °.

Design concept according to the present invention, in step S6 of the present invention, the rolling diameter of tin cream is 9~15mm.

Design concept according to the present invention, in step S2 of the present invention, the thickness of the first welding resistance oil reservoir is greater than0.1mm。

Compared with prior art, the present invention have it is following the utility model has the advantages that

The method provided by the invention for printing different-thickness tin cream on a printed circuit, is used only common steel mesh, passes throughThe thickness that two layers of welding resistance oil reservoir adjusts prepared tin cream can reach preferable printing effect, both drop without making ladder steel meshLow process costs, while more solving ladder steel mesh to the restricted of components' placement.

Detailed description of the invention

To describe the technical solutions in the embodiments of the present invention more clearly, make required in being described below to embodimentAttached drawing is briefly described, it should be apparent that, drawings in the following description are some embodiments of the invention, for abilityFor the those of ordinary skill of domain, without creative efforts, it can also be obtained according to these attached drawings other attachedFigure.

Fig. 1 is the flow diagram of print solder paste on the printed circuit board of one embodiment of the invention offer；

Fig. 2 to Fig. 9 is the structural schematic diagram of print solder paste on printed circuit board provided in an embodiment of the present invention；

Figure 10 is the structural schematic diagram of the common steel mesh covered on printed circuit board provided in an embodiment of the present invention；

In figure:

10, printed circuit board；20a, the first pad area；20b, the second pad area；20c, non-pad area；30, the first welding resistanceLayer；40, the second solder mask；40a, the first printing zone；50, steel mesh；50a, the first printing hole；50b, the second printing hole；50c,Steel mesh ontology；60, tin cream.

Specific embodiment

It is clear in order to be more clear the purpose of the present invention, technical solution and advantageous effects, below in conjunction with this hairAttached drawing in bright embodiment, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that describedEmbodiment is only a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, this fieldThose of ordinary skill's every other embodiment obtained without making creative work, belongs to protection of the present inventionRange.

As shown in Fig. 1, a kind of printing process of tin cream comprising following steps:

Step S1: a printed circuit board 10 is provided, there is the first pad area on the upper surface of the printed circuit board 1020a, the second pad area 20b and non-pad area 20c, print solder paste thickness needed for the first pad area 20a are greater than described secondPad area 20b；

Step S2: the first solder mask 30 is prepared on the non-pad area 20c；

Step S3: the second solder mask 40 is prepared on first solder mask 30；

Step S4: the second solder mask 40 removed around the second pad area 20b forms the first Printing Zone 40a；

Step S5: one layer of steel mesh 50 is covered on second solder mask 40；

Step S6: being applied tin cream 60 on the steel mesh 50, moved on the steel mesh 50 using scraper, the scraper warpThe steel mesh 50 deformation sinks and is close to first solder mask 30 when crossing the first Printing Zone 40a, press the scraper make it is describedTin cream 60 on steel mesh 50 passes through the steel mesh 50 and is coated on the first pad area 20a, the second pad area 20b, instituteState around the second pad area 20b and the second pad area 20b to lower recess, make to be covered on the second pad area 20b andThe thickness of tin cream 60 around the second pad area 20b is less than the thickness for being covered on the tin cream 60 of the first pad area 20aDegree；

Step S7: the steel mesh 50 is removed.

Common steel mesh is used only in the method for print solder paste provided by the invention, by prepared by two layers of welding resistance oil reservoir adjustingThe thickness of tin cream can reach preferable printing effect without making ladder steel mesh, both reduce process costs, while more solvingLadder steel mesh determined to the restricted of components' placement.

With reference to the accompanying drawings, the printing process of the tin cream is elaborated.

Attached drawing 2 is please referred to, step S1 is executed, a printed circuit board 10 is provided.Since different electronic components is mountedThe thickness of required tin cream 60 is different, has the first pad area 20a, the second pad on the upper surface of the printed circuit board 10The thickness of print solder paste 60 needed for area 20b and non-pad area 20c, the first pad area 20a is greater than the second pad area 20bThickness；

Attached drawing 3 is please referred to, step S2 is executed, prepares the first solder mask 30 on the non-pad area 20c.；Described firstSolder mask 30 is prepared by welding resistance oil, and the welding resistance oil includes epoxy resin, emulsion, solvent, filler and pigment, toolProduction procedure are as follows: use laser printing, using film as print media, make welding resistance film；By printed circuit to be printed10 surface cleaning of plate is clean, air-dries after washing；The welding resistance oil is uniformly coated to printing electricity in a manner of silk-screen or roller coating10 surface of road plate；Printed welding resistance film is be overlapped with printed circuit board 10, and between printed circuit board 10 and welding resistance film notIt interspaces, is placed in a length of 365nm of ultraviolet light wave, is exposed under the ultraviolet lamp that power is 5~10W；After the solidification of liquid solder mask oilWelding resistance film is removed, by uncured liquid welding resistance oil on the first pad area 20a being blocked and the second pad area 20b with anhydrousAlcohol or banana oil are wiped, and are rinsed with clear water, air-dry, the first solder mask 30 is made.Preferably, the first prepared welding resistance oil reservoirThickness be greater than 0.1mm.

Attached drawing 4 is please referred to, step S3 is executed, prepares the first solder mask 30 in preparation 40 process of the second solder mask and step S2Unanimously.

It please refers to attached drawing 5 and attached drawing 6, executes step S4, the second solder mask 40 around the second pad area 20b is consolidated at itIt is removed after change, forms the first Printing Zone 40a.

Attached drawing 7 and attached drawing 10 are please referred to, step S5 is executed, one layer of steel mesh 50 is covered on second solder mask 40.InstituteStating steel mesh 50 further includes ontology 50c and the posting (not shown) being set on the outside of ontology 50c, by the posting to describedSteel mesh 50 positions.The steel mesh 50 of going back includes the first printing hole 50a and the second printing hole 50b through the ontology, and described thePosition and the size of one printing hole 50a and the second printing hole 50b and the first pad area 20a and the second pad area 20bIt is corresponding.

Attached drawing 8 is please referred to, step S6 is executed, tin cream 60 is applied on the steel mesh 50, scraper is with certain speed and angleDegree moves forward, and certain pressure is generated to tin cream 60, pushes 60 rolls forward of tin cream.Scraper moves on the steel mesh 50,When the scraper passes through the first Printing Zone 40a, the steel mesh 50 is sunk by the pressure distortion of scraper and is close to first resistanceLayer 30, pressing the scraper makes the tin cream 60 on the steel mesh 50 pass through the steel mesh 50 coated on first pad areaOn 20a, the second pad area 20b, to lower recess around the second pad area 20b and the second pad area 20b, coverCover the tin cream 60 of the second pad area 20b thickness be less than be covered on the first pad area 20a tin cream 60 thickness；

When the pressure of scraper is pressure when scraper just scrapes the tin cream on most steel mesh 50, the angle of scraper and steel mesh 50 is45~60 °, when the rolling diameter of tin cream 60 is 9~15mm, the coating of tin cream 60 is uniform, and effect is preferable.

Attached drawing 8 is please referred to, step S7 is executed, the steel mesh 50 is removed.

As described above, on printed circuit board of the present invention print solder paste method, pass through preparation the first solder mask 30With the second solder mask 40, removal needs to print the second solder mask 40 of the first Printing Zone 40a of thin tin cream thickness, borrows steel knife pressurePower makes the deformation of steel mesh 50 be close to the first solder mask 30, reaches and prepares different-thickness tin cream 60 on same printed circuit board 10Purpose.Common steel mesh 50 is used only in this method, and the thickness of prepared tin cream 60 is adjusted by the first solder mask 30 and the second solder mask 40Degree, without making ladder steel mesh, can reach preferable printing effect.Both process costs are reduced, while more solving ladderSteel mesh is to the restricted of components' placement.

Claims (9)

1. a kind of printing process of tin cream, is used for the print solder paste in printed circuit board assembling process, which is characterized in that describedThe printing process of tin cream its include the following steps:

Step S1: a printed circuit board is provided, there is the first pad area, the second pad area on the upper surface of the printed circuit boardAnd non-pad area, print solder paste thickness needed for first pad area are greater than second pad area；

Step S2: the first solder mask is prepared on the non-pad area；

Step S3: the second solder mask is prepared on first solder mask；

Step S4: the second solder mask removed around the second pad area forms the first Printing Zone；

Step S5: one layer of steel mesh is covered on second solder mask；

Step S6: applying tin cream on the steel mesh, and using scraper in the steel online mobile, the scraper is by the first printingThe steel mesh deformation sinks and is close to first solder mask when area, and pressing the scraper makes the tin cream on the steel mesh pass through instituteSteel mesh is stated coated on first pad area, on second pad area, second pad area and second pad areaSurrounding makes the thickness for the tin cream for being covered on second pad area be less than the tin cream for being covered on first pad area to lower recessThickness；

Step S7: the steel mesh is removed.

2. a kind of printing process of tin cream according to claim 1, which is characterized in that the steel mesh further includes ontology and setsIt is placed in the posting of outer body, the steel mesh is positioned by the posting.

3. a kind of printing process of tin cream according to claim 2, which is characterized in that in step S5, the steel mesh includesThrough the first printing hole and the second printing hole of the ontology, first printing hole and the second printing hole and first padThe position and size of area and second pad area are corresponding.

4. a kind of printing process of tin cream according to claim 1, which is characterized in that the first solder mask described in step S2With the second solder mask described in step S3 by the welding resistance oil of liquid under ultraviolet excitation, be cross-linked into solid-state and be prepared.

5. a kind of printing process of tin cream according to claim 3, which is characterized in that the welding resistance oil includes asphalt mixtures modified by epoxy resinRouge, emulsion, solvent, filler and pigment.

6. a kind of printing process of tin cream according to claim 3, which is characterized in that the ultraviolet light wave of the ultraviolet irradiationA length of 365nm, power are 5~10W.

7. a kind of printing process of tin cream according to claim 1, which is characterized in that in step S6, scraper and steel meshAngle is 45~60 °.

8. a kind of printing process of tin cream according to claim 1, which is characterized in that in step S6, the rolling of the tin creamDynamic diameter is 9~15mm.

9. a kind of printing process of tin cream according to claim 1, which is characterized in that in step S2, first welding resistanceThe thickness of oil reservoir is greater than 0.1mm.