CN100459828C

CN100459828C - Printing circuit board

Info

Publication number: CN100459828C
Application number: CNB2005100835581A
Authority: CN
Inventors: 陈誉升
Original assignee: Lite On IT Corp
Current assignee: Lite On IT Corp
Priority date: 2005-07-11
Filing date: 2005-07-11
Publication date: 2009-02-04
Anticipated expiration: 2025-07-11
Also published as: CN1897792A

Abstract

The invention has a circuit layer located on its baseplate surface and having grids. The circuit layer has even numbers of meshes by which the separation between the circuit layer and the baseplate can be avoided in the process of welding the electronic components. Meanwhile the circuit layer with grids can provide better anti-electromagnetic wave effect.

Description

Printed circuit board (PCB)

Technical field

The invention relates to a kind of printed circuit board (PCB), refer to a kind of printed circuit board (PCB) that can high temperature resistant processing procedure especially.

Background technology

In the past of shortcoming environmental consciousness, be arranged at printed circuit board (PCB) (Print Circuit Board in the mode of plug-in unit (DIP) or surface adhering (SMT); PCB) various master, passive component and chip on are to utilize to have lead welding tin to have Pb-Sn paste to be connected with the etched circuit of printed circuit board surface in the mode of reflow with welding or utilization, to reach the purpose of electric connection.

The Pb-Sn paste that has that uses with general tradition is example, the content of tin lead be tin account for 63% and lead account for 37%, its fusing point be Celsius 183 the degree, and its maximum temperature in back welding process must reach Celsius 210 the degree.In recent years, along with environmental consciousness comes back, European WEEE laws and regulations requirement bans use of lead in electronic welding.In order to meet the regulation of rules, develop the use that lead-free tin cream now gradually.

At present common lead-free tin cream is the SAC alloy, and its fusing point is more traditional the Pb-Sn paste height, is about 217 degree Celsius, and it is in the maximum temperature of back welding process even reach 250 degree Celsius.

Because in leadless process, the temperature of processing procedure obviously improves, therefore in traditional processing procedure, just can cause new problem.Below will be according to the structure of printed circuit board (PCB), with and the problem that in leadless process, produced, do an explanation.

The surface circuit structure of printed circuit board (PCB) comprises circuit region and access area, and circuit region is to form circuit, the usefulness of power supply sub-component or chip conducting telecommunication, and the access area is as the usefulness of ground connection (ground).

As Fig. 1, Fig. 1 be known technology printed circuit board (PCB) 2 overlook outward appearance and side sectional view.Printed circuit board (PCB) 2 is made up of substrate 6 and the circuit layer 8 that invests substrate 6 surfaces.Substrate 6 is broadly divided into FR1 substrate, CEM1 substrate, reaches CEM3 substrate etc. according to the difference of its material.Circuit layer 8 generally is for using a copper foil layer, and etches above-mentioned circuit region and access area on copper foil layer.In addition, generally the outer surface in circuit layer 8 (being copper foil layer) can be provided with the anti-weldering of one deck enamelled coating 10 (the green lacquer of promptly anti-weldering) again, in order to the surface circuit structure on the protection printed circuit board (PCB).

Yet in the test of leadless process that lead-free tin cream was carried out, large stretch of copper foil layer 8 of the access area on the known used printed circuit board (PCB) 2 can generally produce bubble 4, the subregion that is copper foil layer 8 can be heaved as bubble, and separate with substrate 6, so, can form serious electric defect.

Its analysis of causes has two at least: one, because copper foil layer 8 is different with the thermal coefficient of expansion of substrate 6, under the factor that process temperatures improves, it is relative the change greatly of difference of swell increment between the two, and copper foil layer 8 and substrate 6 are peeled off.Its two because process temperatures improves, substrate 6 can produce volatilization gas and aqueous vapors, under the situation of draining nowhere, and lodges in copper foil layer 8 and 6 of substrates, so forms bubble 4.

Therefore, main purpose of the present invention is to provide a kind of printed circuit board (PCB) that can high temperature resistant processing procedure, to address the above problem.

Summary of the invention

Purpose of the present invention is providing a kind of printed circuit board (PCB) that can high temperature resistant processing procedure, can effectively avoid after carrying out leadless process, producing Copper Foil and heave flaw as bubble, with safeguard printed circuit board (PCB) in addition the electrical quality of machine plate behind the part.

According to purpose of the present invention, a kind of printed circuit board (PCB) (PCB) is proposed, be to comprise a substrate, at least one circuit layer.Wherein, circuit layer is to be arranged at substrate surface, and circuit layer has a plurality of mesh and forms at least one latticed zone.

By printed circuit board (PCB) of the present invention, utilize the design of latticed circuit layer, can avoid in high temperature process, producing circuit layer and heave flaw as bubble, with safeguard printed circuit board (PCB) in addition the electrical quality of machine plate behind the part.

Can be further understood by following detailed Description Of The Invention and institute's accompanying drawing about the advantages and spirit of the present invention.

Description of drawings

Fig. 1 be known technology printed circuit board ground district overlook outward appearance and side sectional view;

Fig. 2 is the schematic appearance of printed circuit board (PCB);

Fig. 3 be in the printed circuit board (PCB) of the present invention the access area overlook outward appearance and side sectional view; And

Fig. 4 is the schematic diagram of the grid regions and the mesh specification of circuit layer of the present invention.

Embodiment

The invention relates to a kind of printed circuit board (PCB) (PCB), the source of intention has been when machine plate in making CD-ROM drive, can avoid copper foil layer to produce the printed circuit board (PCB) of bubble when lead-free tin cream carries out surface adhering (SMT), this printed circuit board (PCB) is to be the required base material of machine plate in the CD-ROM drive.

At present, the printed circuit board (PCB) of the used machine plate of CD-ROM drive is for a laminar substrate and upper and lower surface one circuit layer to be set respectively.Circuit layer is to be a conductive material, and the general common Copper Foils that use are used as this circuit layer more, and substrate is to adopt FR1 substrate, CEM1 substrate or CEM3 substrate etc. mostly.In the present embodiment, will use Copper Foil as circuit layer, promptly the copper foil layer of the following stated illustrates correlation technique feature of the present invention.

As Fig. 2, Fig. 2 is the schematic appearance of printed circuit board (PCB) 30.Circuit structure on the printed circuit board (PCB) 30, be to etch a circuit region 32 and an access area 34 in copper foil layer (being circuit layer) in etched mode, circuit region 32 is to form circuit, the usefulness of power supply sub-component or chip conducting telecommunication, access area 34 is as ground connection (ground), and has the function of electromagnetic wave (EMI) protection.

See also Fig. 3, Fig. 3 be in the printed circuit board (PCB) 30 of the present invention access area 34 overlook outward appearance and side sectional view.Printed circuit board (PCB) 30 of the present invention comprises a substrate 42, at least one copper foil layer 44 and at least one anti-weldering enamelled coating 46.Copper foil layer 44 is to be arranged at substrate 42 surfaces, and has a plurality of mesh 4402 and form at least one latticed zone.Anti-weldering enamelled coating 46 is to be arranged at the surface that copper foil layer 44 differs from substrate 42 1 sides.

In the present embodiment, copper foil layer 44 is to be provided with a plurality of mesh 4402 in its access area 34, and makes access area 34 form latticed zone.By these mesh 4402, can reduce the bonding area of 44 of substrate 42 and copper foil layers, and then reduce substrate 42 and copper foil layer 44 in high temperature process because of the different thermal stress that thermal coefficient of expansion caused, separate with substrate 42 in the reflow program, to avoid copper foil layer 44.In addition, the volatilization gas that produced of substrate 42 and aqueous vapor also can be discharged from mesh 4402.

Further specify, see also Fig. 4, Fig. 4 is the schematic diagram of latticed regional 34 and mesh 4402 specifications of circuit layer 44 of the present invention.Printed circuit board (PCB) 30 as the aforementioned, and according to present embodiment, the area A of wherein overlooking mesh 4402 is less than 0.2mm2, and the space D of adjacent two mesh 4402 in these mesh 4402, are less than 0.5mm.No matter and these mesh 4402 be proper alignment or scattered arrangement all can, and mesh 4402 can be any geometry.

By printed circuit board (PCB) of the present invention, utilize latticed circuit layer design, can effectively improve the heat of substrate when bearing high temperature process and evenly reach thermal expansivity, and the high temperature resistant degree of raising substrate, avoid producing circuit layer and heave flaw as bubble, with safeguard printed circuit board (PCB) in addition the electrical quality of machine plate behind the part, to promote the reliability of product.In addition,, can need not change under the situation of substrate material, effectively improve the heat-resisting degree of substrate, and then reduce the cost of material by the latticed design of circuit layer.

By the above detailed description of preferred embodiments, be to wish to know more to describe feature of the present invention and spirit, and be not to come category of the present invention is limited with above-mentioned disclosed preferred embodiment.On the contrary, its objective is that hope can contain in the category that is arranged in the claim protection range that the present invention desires to apply for a patent of various changes and tool equality.

Claims

1, a kind of printed circuit board (PCB) is characterized in that, comprises:

One substrate; And

At least one circuit layer is arranged at this substrate surface, and this circuit layer has a plurality of mesh and form at least one latticed zone, by these mesh, separates with this substrate to avoid this circuit layer.

2, printed circuit board (PCB) as claimed in claim 1 is characterized in that, this printed circuit board (PCB) more comprises an anti-weldering enamelled coating, and this anti-weldering enamelled coating is to be arranged at the surface that this circuit layer differs from this substrate one side.

3, printed circuit board (PCB) as claimed in claim 1 is characterized in that, wherein this circuit layer is to be conductive material.

4, printed circuit board (PCB) as claimed in claim 3 is characterized in that, wherein this circuit layer is to be Copper Foil.

5, printed circuit board (PCB) as claimed in claim 1 is characterized in that, wherein the area of this mesh is in 0.01mm ²To 0.2mm ²Scope between.

6, printed circuit board (PCB) as claimed in claim 1 is characterized in that, wherein distance is between 0.01mm to 0.5mm scope between adjacent two mesh in these mesh.

7, printed circuit board (PCB) as claimed in claim 1 is characterized in that, wherein this printed circuit board (PCB) is to be used in the required base material of machine plate in the CD-ROM drive.

8, printed circuit board (PCB) as claimed in claim 1 is characterized in that, wherein this circuit layer further comprises a circuit region and an access area, and this circuit region is to form circuit, and these mesh are to be arranged at this access area.

9, printed circuit board (PCB) as claimed in claim 1 is characterized in that, this printed circuit board (PCB) is to be applicable to the processing procedure that uses lead-free tin cream.