Method for manufacturing multilayer printed circuit board

1. A method for manufacturing multilayer printed circuit board, comprising:

providing a metal substrate having a first surface and an opposite second surface, the metal substrate comprising a plurality of substrate units, each substrate unit comprising a layer template and a border region surrounding the layer template;

attaching a first insulating layer to the metal substrate, the first insulating layer having a plurality of first through holes proximate to the first surface of the metal substrate, each first through hole being arranged directly above a corresponding layer template;

forming electrically conductive circuits by removing a portion of each layer template, a part of each electrically conductive circuit being exposed through the corresponding first through hole;

forming a second insulating layer on the second surface of the metal substrate, the second insulating layer having a plurality of second through holes, the second insulating layer having the plurality of second through holes aligned with the respective first through holes, each electrically conductive circuit being exposed through the corresponding second through hole;

forming a first metal cylinder in each first through hole, the first metal cylinder protruding from the first insulating layer;

forming a second metal cylinder in each second through hole, the second metal cylinder protruding from the second insulating layer, the corresponding first and the second insulating layers of the electrically conductive circuits and the first and the second metal cylinders cooperatively forming circuit board units; and

folding and laminating the circuit board units in a manner that the circuit board units are stacked one on another, the electrically conductive circuits of each two neighboring laminated circuit board units being electrically connected by means of aligning and contacting the first metal cylinders thereof or the second metal cylinders thereof.

2. The method of claim 1 , wherein the first insulating layer further has a plurality of first alignment holes, each first alignment hole is defined in a respectively border region, a plurality of second alignment holes are defined in the respective border regions of the substrate units, the second insulating layer further has a plurality of third alignment holes, each third alignment hole is defined in a respectively border region, each first alignment hole communicates with the respectively second and third hole, the first, second and third alignment holes of the circuit board units are aligned with each other when the circuit board units are folded and laminated.

3. The method of claim 2 , wherein the first metal cylinders are formed by printing solder paste in the first through holes, the second metal cylinders are formed by printing solder paste in the second through holes.

4. The method of claim 3 , wherein after printing solder paste in the second through hole, the solder paste in the second through holes are treated by a high temperature reflow and setting process.

5. The method of claim 2 , wherein prior to folding the plurality of circuit board units, an adhesive sheet is formed on one of the first insulating layer and the second insulating layer.

6. The method of claim 5 , wherein each adhesive sheet has at least one second through hole, the first metal cylinders and the second metal cylinders extending through the corresponding third alignment holes.

7. The method of claim 2 , wherein the first metal cylinders or the second metal cylinders, which are aligned and contact each other in each two neighboring laminated circuit board units, are heated and melt to form a single body.

8. The method of claim 2 , further comprising cutting off the border region of each of the circuit board units after folding and laminating the circuit board units.

9. The method of claim 2 , wherein the plurality of substrate units are arranged along a longitudinal direction of the metal substrate.

10. The method of claim 9 , wherein the plurality of substrate units have a same shape and size.

11. The method of claim 1 , wherein the first through holes and the second through holes in two neighbor circuit board units are symmetrical with respect to an imaginary boundary between the two neighboring circuit board units.

12. The method of claim 11 , wherein the first metal cylinders are formed by printing solder paste in the first through holes, the second metal cylinders are formed by printing solder paste in the second through holes.

13. The method of claim 12 , wherein after printing solder paste in the second through hole, the solder paste in the second through holes are treated by a high temperature reflow and setting process.

14. The method of claim 11 , wherein prior to folding the plurality of circuit board units, an adhesive sheet is formed on one of the first insulating layer and the second insulating layer.

15. The method of claim 14 , wherein each adhesive sheet has at least one second through hole, the first metal cylinders and the second metal cylinders extending through the corresponding third alignment holes.

16. The method of claim 11 , wherein the first metal cylinders or the second metal cylinders, which are aligned and contact each other in each two neighboring laminated circuit board units, are heated and melt to form a single body.

17. The method of claim 11 , further comprising cutting off the border region of each of the circuit board units after folding and laminating the circuit board units.

18. A method for manufacturing multilayer printed circuit board, comprising:

providing an elongated metal substrate having a first surface and an opposite second surface, the metal substrate comprising a plurality of substrate units arranged along a longitudinal direction thereof, each substrate unit comprising a layer template and a border region surrounding the layer template;

attaching a first insulating layer to the metal substrate, the first insulating layer having a plurality of first through holes proximate to the first surface of the metal substrate, each first through hole being arranged directly above a corresponding layer template;

forming electrically conductive circuits by removing a portion of each layer template, a part of each electrically conductive circuit being exposed through the corresponding first through hole;

forming a second insulating layer on the second surface of the metal substrate, the second insulating layer having a plurality of second through holes, the second through holes being aligned with the respective first through holes, each electrically conductive circuit being exposed through the corresponding second through hole;

forming a first metal cylinder in each first through hole, the first metal cylinder protruding from the first insulating layer;

forming a second metal cylinder in each second through hole, the second metal cylinder protruding from the second insulating layer, the corresponding first and the second insulating layers of the electrically conductive circuits and the first and the second metal cylinders cooperatively forming circuit board units; and

folding and laminating the circuit board units in a manner that the circuit board units are stacked one on another, the electrically conductive circuits of each two neighboring laminated circuit board units being electrically connected by means of aligning and contacting the first metal cylinders thereof or the second metal cylinders thereof.

19. The method of claim 18 , wherein the first through hole and the second through holes in two neighboring circuit board units are symmetrical with respect to an imaginary boundary between the two neighboring circuit board units.

20. The method of claim 19 , wherein the plurality of substrate units have a same shape and size.