CMA3000 Assembly Instructions

6.6

Component placement

An accurate alignment of the component is an important process step although the surface tension

of the solder during the reflow step will help with the self-alignment. The use of a split-vision

alignment system is recommended to ensure the precise alignment of the component to the PWB.

The Z placement force should be carefully controlled in order to prevent the solder bridging,

component damage and misalignment.

6.7

Reflow soldering

The same reflow profile, as for the component removal, can be used for the re-attachment of the

replacement component as long as all solder joints will fully melt and properly wet the contact

areas. Otherwise, a new and proper reflow profile must be developed and measured from the

solder joints. Note that the reflow profile is always solder paste and flux dependent. The reworked

PWBs should be allowed to cool to the room temperature. The PWBs and the components should

be inspected after the rework process for possible defects. The use of X-ray inspection techniques

can be used to verify the success of the rework process.

7

Hand Soldering Guidelines

Hand soldering of the CMA3000 component with soldering iron is not recommended. For proto-

uses of the CMA3000 component, VTI can provide pre-assembled component on a PWB. For

more information on this, please find the document CMA3000-D0X PWB specification 8287500A

and CMA3000-D0X PWB specification 8287600A. These can be found from the Internet at

www.vti.fi.

8

Environmental Aspects

VTI Technologies respects environmental values and thus its CoM packaged accelerometer

sensors are lead-free and RoHS compatible. VTI Technologies’ sensors should be soldered with

lead-free solders in order to guarantee full RoHS compatibility.

9

Effect of the Reflow Soldering

CMA3000 is a factory calibrated three-axis accelerometer. However, reflow soldering may cause

acceleration offset shift due to thermal stress induced to the component. Offset shift depends e.g.

on the used layout design, circuit board material and the manufacturing process. Offset shift

stabilizes typically in 6 h after the reflow and is typically less than 150 mg (1σ). Calibration is not

recommended prior the offset has settled.

Typical offset settling behavior after the soldering can be seen in Figure 14 below.

Subject to changes

TN68

16/18

Rev.09

PRELIMINARY

VTI Technologies Oy

www.vti.fi