Patent Application
20110024173
This application claims priority to Taiwan Application Serial Number 98125399, filed Jul. 28, 2009, which is herein incorporated by reference.
1. Field of Invention
The present invention relates to a ball grid array printed circuit board. More particularly, the present invention relates to a non-solder mask defined ball grid array printed circuit board.
2. Description of Related Art
Access to an electrical connection with an external circuit is required for an IC chip to function properly, and an IC device has to be packaged to prevent damage from external force or environmental factors during conveyance or pick-and-place procedures. Electronic packaging is a necessary process in integrated circuit production to allow the IC device to perform a predefined function under an organized structure and provides protection.
A ball grid array (BGA) package has been a widely used electronic package structure in integrated circuit production. The BGA package structure has plural solder balls or soldering bumps to bond the IC chip on a printed circuit board and to electrically connect conductive wires (or trace) on the printed circuit board (PCB).
Lead free process has become a consensus in recent years for environmental consciousness. However, the processing temperature in the lead free PCB process is 30-40° C. higher than the processing temperature of lead containing PCB process. Furthermore, the lead free solder ball is stiffer than conventional PbSn solder ball. Therefore, the dielectric material crack under the pad would be easily occurred.
An embodiment of the invention provides a ball grid array printed circuit board. The ball grid array printed circuit board includes a substrate having a dielectric material layer, a solder mask formed on the dielectric material layer, a ball grid array pad formed on the dielectric material layer, a gap formed between the ball grid array pad and the solder mask, and an adhesive glue filled in the gap.
Another embodiment of the invention provides a ball grid array printed circuit board package structure. The ball grid array printed circuit board package structure includes a ball grid array printed circuit board and a semiconductor device. The ball grid array printed circuit board includes a substrate having a dielectric material layer, a solder mask formed on the dielectric material layer, a ball grid array pad formed on the dielectric material layer, a gap formed between the ball grid array pad and the solder mask, and an adhesive glue filled in the gap. The semiconductor device includes a solder ball connected to the ball grid array pad.
Another embodiment of the invention provides a method for fabricating a ball grid array printed circuit board. The method includes providing a substrate comprising a dielectric material layer, and then a ball grid array pad and a solder mask are formed on the dielectric material layer. There is a gap between the ball grid array pad and the solder mask. Then, an adhesive glue is filled in the gap.
It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,
Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
The dielectric material layer under the grid ball array (BGA) pad may be easily cracked in the conventional lead free BGA printed circuit board process. The applicant found that those cracks of the dielectric material layers have a similar trend, which is started at the gap between the BGA pad and the solder mask, so that the applicant believed that the bonding strength between the dielectric material layer and the BGA pad at the gap is weaker than other (or have to be enhanced).
The present embodiments provide a ball grid array printed circuit board to enhance the bonding strength between the dielectric material layer and the BGA pad at the gap.
Refer to
Referring to
Referring to
The BGA printed circuit board 200 in this embodiment is a non-solder mask defined (NSMD) type. The solder mask 230 is arranged around the BGA pad 220 in the NSMD BGA printed circuit board 200 to protect the surface of the dielectric material layer 212 and to prevent the semiconductor device from bonding on the incorrect location of the printed circuit board 200. The material of the solder mask 230 is an insulating material, such as a flux.
The adhesive glue 240 can be an epoxy resin or a UV adhesive. The adhesive glue 240 is heated to be solidified in step 140 when the material of the adhesive glue 240 is epoxy resin. The adhesive glue 240 is ultraviolet radiated to be solidified in step 140 when the material of the adhesive glue is UV adhesive.
The adhesive glue 240 is filled in the gap 234 between the BGA pad 220 and the solder mask 230. The adhesive glue 240 bonds with the dielectric material layer 212 and the also bonds with the edge of the BGA pad 220, so that the bonding force between the BGA pad 220 and the dielectric material layer 212 can be enhanced. The BGA pad 220, the adhesive glue 240, and the solder mask 230 become a continuous structure and share the stress in the package process, so that the stress would not be easily conducted to the dielectric material layer 212 via the gap 234 and the risk of cracks for the dielectric material layer 212 can be reduced.
The embodiment of the invention further includes step 160 to step 180, which are disclosed in
Referring to
Refer to
The solder mask 330 can be a flux. The adhesive glue 340 can be epoxy resin or UV adhesive. The substrate 310 can be a FR4 board. There are plural vias (not shown) arranged under the BGA pad 320.
The gap 334 between the BGA pad 320 and the solder mask 330 is filled by the adhesive glue 340. The adhesive glue 340 bonds with the dielectric material layer 312 and also bonds with the edge of the BGA pad 320, so that the bonding force between the BGA pad 320 and the dielectric material layer 312 is enhanced. The BGA pad 320, the adhesive glue 340, and the solder mask 330 become a continuous structure and share the stress in the package process, so that the stress would not be easily conducted to the dielectric material layer 312 via the gap 334 and the risk of cracks for the dielectric material layer 312 can be reduced.
Refer to
The semiconductor device 480, for example, is a surface mounting device. The semiconductor device 480 is fixed on the BGA printed circuit board 410 by a surface mounting process. The solder ball 482 of the semiconductor device 480 would become the solder joint to fix the semiconductor device 480 on the BGA printed circuit board 410. The material of the solder ball 482 is Tin. The solder ball 482 does not touch the BGA printed circuit board 410 in this embodiment.
According to the disclosed embodiments, the gap between the BGA pad and the solder mask is filled by the adhesive glue. The adhesive glue bonds with the dielectric material layer and also bonds with the edge of the BGA pad, so that the bonding force between the BGA pad and the dielectric material layer is enhanced. The BGA pad, the adhesive glue, and the solder mask become a continuous structure and share the stress in the package process, so that the stress would not be easily conducted to the dielectric material layer via the gap and the risk of dielectric material layer cracks can be reduced.
Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 098125399 | Jul 2009 | TW | national |
