Assembly Instructions for SCA6x0 and SCA10x0 series

TN71

VTI Technologies Oy

7/12

www.vti.fi

Rev.1.0

The typical ramp up rate is 3°C/second max. For lead-free soldering with SnAgCu solder the pre-

heat temperature zone is ~ 150°-200° and should last for ~ 60-180 seconds. Time above the

liquidus temperature (~217°C) should be ~ 60-150 seconds. The reflow peak max. temperature

should not exceed 250°. Temperature within actual peak temperature is typically ~20-40 seconds.

Ramp down rate should generally be 6°C/second max.

Figure 8:

Typical convection reflow soldering phases and profile.

The process window for lead-free soldering is narrower than for traditional eutectic SnPb solders.

Thus, caution has to be taken care when adjusting the reflow profiles. The reflow profile should be

measured using a thermo-couple measurement system. It is recommended to use at least three

thermo-couples, depending on the application. As a general guide, one thermo-couple should be

placed under a component having the largest thermal mass, one next to the smallest component,

one should be in contact with DIL component's solder joint, and others to the appropriate spots on

a circuit board, e.g. corner, center, bottom of the board etc. The reflow profile should be adjusted

according to the measured data so that each solder joint experiences an optimal reflow profile. The

temperature gradient should be as small as possible across the circuit board. Extreme caution has

to be taken if the circuit board contains components with highly different thermal masses.

5.7

Moisture sensitivity level (MSL) classification

The Moisture Sensitivity Level of the DIL component is Level 3 according to the IPC/JEDEC J-

STD-020C. This means that the part is delivered in a dry pack bag and the manufacturing floor time

(out of bag) at the customer’s end is 168 hours.

Following instruction shall be followed:

1. Calculated shelf life in sealed bag: 12 months at < 40 °C and < 90% relative humidity (RH).

2. Maximum soldering peak temperature for the package is 250

°C/40sec, measured from the

package body.

3. After bag is opened, devices that will be subjected to reflow solder or other high temperature

process must be

a) Stored at <10% RH,

or

b) Mounted within 168 hours of factor conditions ≤30 °C/60%RH.

Note: Do not re-store devices that have exposed >10% RH conditions

.