LPC2917 datasheet(61/68 Pages) PHILIPS

61 / 68 page

LPC2917_19_1

Preliminary data sheet

Rev. 1.01 — 15 November 2007

61 of 68

NXP Semiconductors

LPC2917/19

ARM9 microcontroller with CAN and LIN

To overcome these problems the double-wave soldering method was specifically

developed.

If wave soldering is used the following conditions must be observed for optimal results:

• Use a double-wave soldering method comprising a turbulent wave with high upward

pressure followed by a smooth laminar wave.

• For packages with leads on two sides and a pitch (e):

– larger than or equal to 1.27 mm, the footprint longitudinal axis is preferred to be

parallel to the transport direction of the printed-circuit board;

– smaller than 1.27 mm, the footprint longitudinal axis must be parallel to the

transport direction of the printed-circuit board.

The footprint must incorporate solder thieves at the downstream end.

• For packages with leads on four sides, the footprint must be placed at a 45° angle to

the transport direction of the printed-circuit board. The footprint must incorporate

solder thieves downstream and at the side corners.

During placement and before soldering, the package must be fixed with a droplet of

adhesive. The adhesive can be applied by screen printing, pin transfer or syringe

dispensing. The package can be soldered after the adhesive is cured.

Typical dwell time of the leads in the wave ranges from 3 seconds to 4 seconds at 250

°C

or 265

°C, depending on solder material applied, SnPb or Pb-free respectively.

A mildly-activated flux will eliminate the need for removal of corrosive residues in most

applications.

14.3.3 Manual soldering

Fix the component by first soldering two diagonally-opposite end leads. Use a low voltage

(24 V or less) soldering iron applied to the flat part of the lead. Contact time must be

limited to 10 seconds at up to 300

°C.

When using a dedicated tool, all other leads can be soldered in one operation within

2 seconds to 5 seconds between 270

°Cand 320 °C.

14.4 Package related soldering information

Table 34.

Suitability of IC packages for wave, reflow and dipping soldering methods

Mounting

Package[1]

Soldering method

Wave

Reflow[2]

Dipping

Through-hole mount

CPGA, HCPGA

suitable

−−

DBS, DIP, HDIP, RDBS, SDIP, SIL

suitable[3]

−

suitable

Through-hole-surface

mount

PMFP[4]

not suitable

−

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