Reflow soldering exploration

Soldering using hand is slow and not easy in quality control, so try reflow soldering method, a solder paste in syringe package is bought and, it contains Sn63/Pb37.

Solder paste is usually apply through solder paste stencil and we don't have a stencil today, we apply it by hand, it takes a steady hand.

next step is placing components on the pads, requires steady hand and intense focus. the pads is bit sticky because of the solder paste, i can't see clearly if the SOIC package IC AD607 is correctly placed, i hope it would goes to the right alignment during reflow.

and insert the board into reflow oven. heat it up using the default temperature profile. it takes about 10 mins, with some bad smell.

after reflow, most of the component is properly soldered, we noticed there are two pins on AD607 is falsely joined together, because of too much solder paste, and some legs of resistor array is not soldered, because the solder paste is not enough, and the lower left side clock IC is drifted away from the pad totally, because the pads are too apart and it not suit for reflow soldering.

The reflow soldering process looks good and it saved a huge amount of manual soldering time, it can be improve in the way that some pads needs to revise in shape to suit for reflow soldering.

a feedforward bpsk demodulation algorithm

SDR receiver system development board

a completed software defined radio receiver system development board, covered frequency range up to 500MHz. going to submit to PCB factory. This design utilized programmable MEMS oscillator as local oscillator.

MIXER and IF amplifier chain: AD607 IF sub-system

ADC: AD9201 dual channel 10-bits ADC

Signal processing: PIC32MX MIPS based microcontroller

USB connectivity: FT245R USB-parallel FIFO

SI501 32kHz to 100MHz Programmable oscillator

Silicon labs SI501 one-time-programmable CMEMS Oscillator

We use crystals oscillator to generate local oscillator, however crystal oscillator comes with fixed frequency and we can only pick the standard frequencies listed by manufacturer, sometimes we needs a particular frequency which is not available in the market. Recently there are some programmable oscillator IC on the market, and these IC using on-chip MEMS resonator as source and PLL circuitry to convert the base frequency to the target frequency, in the range of 32kHz to 100MHz. 

The programmer, comes with a windows GUI, through USB.

I hope I can use these oscillator to replace some of the crystal oscillator in the projects