Patent Application
20060083044
The present invention relates to a “MMC memory card used with TSOP package” and, more particularly, to a MMC memory card suitable for using in digital cameras, handy computers etc. Due to the MMC memory card is a standard specification so the thickness of the MMC memory card is fixed. The present invention reduces the material cost of the flash memory and the manufacturer cost of the plastic housing, meanwhile, the present invention also reaches the goals of good assembled quality and efficiency under the limited conditions such as thickness.
Generally, the prior art MMC memory card is used in digital cameras, handy computers etc.
The assembly structure of the prior art MMC memory card mainly had a plurality of passive elements and various ICs 12 (generally, including flash memories, control chips) installed on the circuit board 11 in sequence, and then sealed the circuit board 11 by molding, gluing or sealing method to form the required printed circuit board, finally, covered a housing 13 (please refer to
However, the prior art MMC memory card has the following drawbacks:
(1). Process is complex: the assembly process of the prior art memory card needs to use molding, gluing or sealing method to seal the printed circuit board and unpackage electric elements (such as passive elements, flash memories and control chips) thereon, therefore, the assembly process of the prior art memory card is more complex.
(2) The cost of the IC is higher: the prior art memory card uses the aforesaid assembly process, due to the thickness of the memory card needs to be limited to 1.4 mm, so the thickness of the IC adapted by the memory card is limited and causes to increase the cost of the IC, meanwhile increases the difficulty of the assembly process and the cost of the elements.
(3) The cost of the housing is higher: due to the aforesaid thickness limited, the thickness of the housing covering the printed circuit board is also limited, thus causing the difficulty of the assembly process and increasing the cost.
(4) The yield rate is lower: in order to assemble the unpackaged IC on the printed circuit board, damage to the unpackaged IC usually happens during the assembly process, thus also causing a lower yield rate.
According to one aspect of the present invention, the present invention replaces the unpackaged flash memory by the TSOP (Thin Small Outline Package) type package flash memory. The TSOP flash memory has been packaged at the factory, so the transport, the convenience of the assembly are satisfied than the IC component used in the prior art memory card. Furthermore, the TSOP flash memories are mass produced, so the memory card producers buy them easier from the market and at a lower price. Due to the TSOP flash memories have popularly been used in the flash memory ICs, so the supply source can be found in various ways and can be mass-produced immediately so that the cost is decreased. The capacity of the TSOP type memory is also larger than the others packaged types of flash memory of the same size; thus can reduce the assembly cost of the present invention's MMC memory card and has a larger capacity. Due to the thickness of the MMC memory card including the printed circuit board with the IC mounted thereon is limited to 1.4 mm, the present invention uses a well-designed housing for example but not limited to a molded plastic housing with a window structure and cooperates with the TSOP type flash memory and SMT to form a memory card by mounting side-direction pins on the printed circuit board, thus can easy control the thickness of the memory card to 1.4 mm. Wherein, the molded plastic housing enables its top surface to align with the top surface of the flash memory, and only the top surface of the flash memory can be seen from the window so as to form the MMC memory card with the thickness limited to 1.4 mm. Further, a sticker can be stuck over the window to improve the shielding effect. Further, using multiple layers frame design or housing with extreme thickness can also control the thickness of the MMC memory card to 1.4 mm easily.
Furthermore, the TSOP type flash memory cooperated to the SMT design also uses thicker flash memory, cooperating with the well-designed housing to increase its capacity and increase the product value by using thicker memory card and capacity flash memory and with the same thickness, thus can reduce the fabrication cost and improve the competition of the product.
The present invention has the following advantages:
To reduce the flash memory's cost: due to the present invention using adapted housing to position the printed circuit board with thicker TSOP type flash memory that is mounted thereon, so that it can reduce the flash memory and the memory card's cost, and due to the TSOP type flash memory has sufficient supply sources, so the flash memory's cost can further be decreased.
The percent defective rate is lower: during the assembly process, due to the present invention uses the TSOP type flash memory that is already packaged in the factories, so it involves less risks to damage the packaged IC, and thus also increases the throughput.
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It should be noted that the MMC memory card cooperated with the aforesaid assembled structure of the present invention doesn't need the traditional molding, gluing, or sealing method to seal the passive elements 22, flash memory 23, control chip 24 etc., so as to reach the goals of sealing and isolating effect, further, it also can reduce the assembly process, reduce the assembly cost and ensure the packaged quality and performance of the memory card.
Furthermore, according to the international standard specification, the total thickness of the memory card should be limited to 1.4 mm. While the memory card 20 of the present invention, the thickness of the circuit board 21 is 0.3 mm, the height between the circuit board 21 and the top surface of the elements is 1.1 mm, and the thickness of the sticker is less than 0.1 mm; therefore, the total thickness of the memory card of the present invention matches the 1.4±0.4 mm specification, so the memory card of the present invention is suitable to the electronic product required memory card in the market.
Furthermore, the memory card of the present invention can appropriately increase the molding thickness of the housing 25 to increase the strength of the memory card 20.
Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.
