cancel
Showing results for 
Search instead for 
Did you mean: 

About LSM330DLC Gyroscopes reflow solder problem

cac2012
Associate
Posted on June 11, 2014 at 07:32

We used 

LSM330DLC Gyroscopes in electric self-balancing unicycle. There is one problem of 

LSM330DLC

  after

reflow solder. 

The 

LSM330DLC

 has offset to detect 

the angle from the vertical direction. The offset may be 0-7 degree, but they are still in good working condition.

I made 1000 units of  

LSM330DLC

 based controller two times using 

reflow solder

.

 The ratio is about 15% that has offset problem. Others are good.

How to solve this problem?

Do you think the 

LSM330DLC

 are 

affected by damp? 

The caution about 

LSM330DLC is as follows.

1.After sealed bag is opened, devices that subjected to reflow solder must

a) mounted within: 168 hours at factory conditions <30 

℃/60%RH

b) stored at <10

℃/60%RH

The 

LSM330DLC

 is not stored with above condition

 I really didn't bake them befor 

reflow solder.

Do you think the offset problem can be solved if I baked the 

LSM330DLC

 before 

reflow solder?

Thanks

my email is: xmgatech@gmail.com
1 REPLY 1
ivani
Associate II
Posted on June 13, 2014 at 12:46

I may be wrong but it could be a normal zero-g offset distribution.

It is stated as 60mg typical value in the datasheet, which usually means that this is 1-sigma value.

In other words only 68% of devices will fit in this number. About 95% will fit within +/-120mg and the rest could go up to +/-180mg (if we assume that ST is not allowing more than 3-sigma deviation of the devices out of the production).

Probably you shall do some zero-g calibration for each board and store it in a NV memory.

Be aware also that it will change with the temperature and might be not fully repeatable from power on to power on cycle.