PCBRM_User_Manual_R9.pdf - 第66页

PCBRM15 & PCBRM System 5.2 User’s Manual

Chapter 4: Processes & Applications

Part No. 4005.00.906 4-23

• It may be desired to turn on solder flow while board is in the preheat position to allow flow well to

heat soak and dross to be skimmed prior to soldering.

• Reduce bridging by adjusting Ramp Down Flow Rate to zero (0). Or, manually raise board slowly

with Z-Axis Adjustment Wheel while solder is still flowing.

• Flux entire lead area. It may be required to flux topside of board. Allow sufficient temperature to a

be achieved to activate flux.

• Board must be level to solder wave. Fixturing may be required.

• The vertical position of the board is critical for proper soldering results. Allow solder to contact all

leads, but sufficient clearance for solder to flow. Bridging may be reduced by raising carrier position

and allowing solder to wick up the leads.

• Using tacky flux may allow more flux to remain during reflow, reducing bridging.

• Increasing preheat may be required for thermal challenging and lead free assemblies.

• It may be desired to lower the process temperature and increase process time if the board is prone

to delamination and/or discoloring.

PCBRM15 & PCBRM System 5.2 User’s Manual

Chapter 4: Processes & Applications

Part No. 4005.00.906 4-24

4.14 Removal Procedure

4.14.1 Set Up

• Set Ramp Down Flow Rate to 10.

• Set Air Regulator to 5-7 psi.

• Follow same procedure for automatic soldering procedure. If manual soldering procedure is used,

the operator must press the footswitch to stop the solder pumping and activate the hole cleaning

system.

4.14.2 Operation

Use automatic or manual procedure as described in soldering section up the when solder is contacting

the board.

Allow sufficient time for solder to contact component leads for easy removal.

Observe component leads and when all leads are molten, lift the component from the board using an

extractor tool that firmly grasps the component body. If solder is still flowing, interrupt cycle by pressing

the right side of the footswitch. Component should lift out easily.

The hole cleaning operation starts immediately at the end of the component removal procedure. There

will be an audible signal that indicates solder has stopped flowing against the board. At this time, lower

the Air Cleaning Hood. It is important that sufficient downward pressure be applied to insure a good

seal between the hood and board surface. Be sure entire area is sealed. Air leakage will prevent

maximum effectiveness of system. Hold is place during the entire time the air is applied.

Low pressure air comes on automatically 1 ½ seconds after the solder stops flowing, forcing the

molten solder to drop from the holes into the empty flow well. The 1 ½ seconds delay prevents

pressurized air from coming in contact with the flowing solder.

The bottom of the board may have bridging or icicling caused by the moving air. The next operation of

resoldering of the replacement component will eliminate these conditions.

Depending upon the heat sink characteristics of the board, the number of leads, and shape of the lead

pattern, there will be some holes that will not be completely clear of solder.

PCBRM15 & PCBRM System 5.2 User’s Manual

Chapter 4: Processes & Applications

Part No. 4005.00.906 4-25

Component Removal Process Notes

Board must be clamped. If not, when removing the component leads may catch in the barrels and lift the

board away from the solder wave during reflow.

Do not set Air Cleaning System too high. It is dangerous and will not improve cleaning of the barrels.

Raising the board preheat temperature may increase the effectiveness of the air cleaning procedure.

For large or low melt plastic devices it is important to apply even removal force when lifting the device

from the board. Two tools/hands may be required. Tools which apply uniform pressure, no pinch points,

will be most effective for low melt plastic devices.

It may be required to use a secondary operation to clean 100% of the board barrels. A vacuum

desoldering hand tool and/or solder wick can be used for most applications.

In the automatic mode the end of solder flow is indicated by an audible signal. Do not attempt to remove

component after the signal.

The board must remain rigid and level during the removal process. Do not pull the board upward away

from the wave or push downward into the wave since this will cause flooding. Fixturing may be required.

4.15 Component Replacement

Reference Soldering procedure.

4.15.1 Automatic Method

After the holes have been cleaned, flux the leads and bottom of the board.

Follow Soldering procedure.

4.15.2 Manual Method

It is possible to insert a replacement component during the removal process while the solder is flowing.

If the operator has sufficient skill, the component can be easily positioned, inserted without bending leads

and solder quality can result then the following method may be used.

After the component is sufficiently removed and with the component leads fluxed and possibly preheated,

the replacement component is inserted with solder flowing.

The cycle is stopped by the footswitch after sufficient reflow or carrier may be raised to enhance solder

peeling.