TW201338568A - Electret condenser microphone - Google Patents

Abstract

A electret condenser microphone comprising a housing to contain a vibrator, a back plate and a circuit board, the housing has a opening in its bottom and the opening is covered by the circuit board, a bottom surface of the circuit board has a first soldering pad and a second soldering pad, wherein the outline of the first soldering pad is the same with the opening, and the soldering pad provide a hollow portion, at least one insulation groove and at least one compartment groove which is communicate to the hollow portion, thus define a soldering area between the hollow portion, the insulation groove and the compartment groove, the second soldering pad located in the hollow portion.

Description

Electret condenser microphone

The invention relates to an electret condenser microphone (ECM), in particular to an electret condenser microphone which reduces the process complexity and manufacturing cost of the pad and simultaneously improves the yield of the reflow.

A conventional electret condenser microphone 10, as shown in the first figure, has a cylindrical casing 11 for accommodating a diaphragm 12 and a back plate 13 constituting a capacitor, and the casing 11 is opposed to the diaphragm 12 The circuit board 14 is disposed on the top surface of the circuit board 14 facing the back surface of the back plate 13 and is spaced apart from the back plate 13. The bottom surface of the circuit board 14 has a plurality of raised pads. 16 is used for signal output and grounding. As shown in the second figure, the pads 16 form a center and a ring pattern, and the microphone 10 is mounted on a substrate by means of the pads 16 for heat reflow ( Not shown in the figure).

In addition to requiring multiple precise positioning to form the pattern, the solder pads 16 need to be plated with a thicker copper layer than other types of microphones to increase the overall thickness to be planned as a tin-added area, except for complicated processes. In addition, a thicker copper layer also requires a higher reflow temperature, which increases the defect rate of defects such as voids or short circuits due to flux flowing in the gap between the board 14 and the substrate during the reflow process. The high temperature process may also cause loss of charge on the backplate 13 to reduce the sensitivity of the electret condenser microphone 10.

In view of the foregoing shortcomings, the main object of the present invention is to provide an electret condenser microphone with an improved pad design, which can reduce the process complexity and manufacturing cost of the pad, and improve the subsequent reflow process yield.

In order to achieve the above object, the present invention provides an electret condenser microphone having a diaphragm, a back plate and a circuit board housed in a casing, and an opening is formed at a bottom of the casing and received by the circuit board. Enclosed, characterized in that: a first pad and a second pad are disposed on a bottom surface of the circuit board, wherein the outer periphery of the first pad has the same shape as the opening and has a hollow region And recessing at least one insulating groove and at least one separating groove communicating with the hollow region, and at least one tin-adding region is disposed between the insulating groove, the dividing groove and the hollow region, and the second bonding pad is Located in the hollow area.

By designing the insulating groove and the separation groove of the second pad, the tin-added region can be planned without additionally plating a thick copper layer, the positioning is also easier, and the yield of the process can be improved, thereby achieving the present invention. purpose.

For a detailed description of the structure, features, and advantages of the present invention, a preferred embodiment is illustrated and described in conjunction with the following drawings.

Referring to the third embodiment, a preferred embodiment of the present invention provides an electret condenser microphone 20 having a diaphragm (not shown), a back plate (not shown), and a circuit board 21 It is disposed in a casing 22, and the bottom of the casing 22 is provided with an opening 221 and is closed by the circuit board 21. Since the foregoing structure is known to those skilled in the art, it will not be described herein. The technical features of the invention are specifically described as follows:

A first pad 30 and a second pad 40 are disposed on the bottom surface of the circuit board 21, wherein the outer periphery of the first pad 30 has the same shape as the opening 221 of the housing 22, in this embodiment. The second pad 40 is disposed in a circular shape, and is provided with a hollow region 31. In the embodiment, the first pad 30 and the second pad 40 are in the same center of the geometric arrangement.

The first pad 30 is further recessed with four partitioning grooves 32 communicating with the hollow region 31, and the three insulating grooves 33 are disposed at a distance from the hollow region 31, thereby arranging that the tetra-tin tin region 34 is located at the same position. The insulating groove 33, the hollow region 31 and the partition portion 32.

It should be noted that the insulating groove 33 can be correspondingly disposed between two adjacent grooves 32 that are adjacent or not adjacent.

Therefore, the present invention only needs two positionings to determine the position of the first pad 30 and the second pad 40, and the present invention plans to add the same through the insulating grooves 33 and the partitions 32. Tin area 34, so no additional copper plating process is required to increase the thickness, so the process can be simplified, the production efficiency can be improved and the cost can be reduced.

In addition, in the present invention, the solder is previously applied to the tin-adding regions 34 and the second pads 31 for reflow, and the cohesive force when the solder is melted is limited because the applied solder is limited to a specific range. Tin dots having an effective height of about 2 to 5 μm will be formed, and the partitions 32 can serve as a discharge passage for the flux volatilized during reflow, thereby avoiding short circuit or poor soldering, and contributing to the reflow process. The yield is low and the reflow temperature can be used to avoid problems caused by the loss of charge on the back plate.

It is emphasized that the number and shape of the partitions and the insulating grooves of the second pad are only in the embodiment, as long as the number is more than one, the tin-added region can be formed, and those skilled in the art can actually meet the actual needs. And make a simple change.

In summary, the electret condenser microphone of the present invention can solve various shortcomings in the traditional process by improving the structure of the solder pad, so as to achieve the purpose of reducing cost and improving yield.

[Prior technology]

10. . . Electret condenser microphone

11. . . case

12. . . Vibrating membrane

13. . . Back plate

14. . . Circuit board

15. . . Electronic component

16. . . Solder pad

[Preferred embodiment]

20. . . Electret condenser microphone

twenty one. . . Circuit board

twenty two. . . case

221. . . Opening

30. . . First pad

31. . . Hollow area

32. . . Separation slot

33. . . Insulating groove

34. . . Jiaxi area

40. . . Second pad

The first figure is a cross-sectional view of a conventional electret condenser microphone.

The second figure is a schematic diagram of the bottom structure of a conventional electret condenser microphone.

The third figure is a schematic view of a pad used in an electret condenser microphone according to a preferred embodiment of the present invention.

20. . . Electret condenser microphone

twenty one. . . Circuit board

twenty two. . . case

221. . . Opening

30. . . First pad

31. . . Hollow area

32. . . Separation slot

33. . . Insulating groove

34. . . Jiaxi area

40. . . Second pad

Claims (5)

An electret condenser microphone having a vibrating membrane, a backing plate and a circuit board are accommodated in a casing, and an opening is formed at a bottom of the casing and is closed by the circuit board, wherein the circuit is a first pad and a second pad are disposed on a bottom surface of the board, wherein the outer periphery of the first pad has the same shape as the opening and has a hollow area, and at least one insulating groove is recessed And a partitioning groove connecting at least one of the hollow regions, wherein at least one tin-adding region is disposed between the insulating groove, the dividing groove and the hollow region, and the second bonding pad is disposed in the hollow region. The first pad and the second pad as claimed in claim 1 are both circular and have a geometric arrangement of the same center. The number of the at least one dividing groove as described in claim 1 is four. The insulating groove according to claim 3 is correspondingly disposed between two of the partitioning grooves and located at a position spaced apart from the hollow region. The number of the at least one insulating groove as described in claim 3 or 4 is three.