Phil Cole
Posts: 755
Joined: 1/27/2002
From: Redwood City, CA, USA
Status: online
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Regarding surface-mount vs. through-hole.
The benefits of SMT are
1. Easier machine assembly.
2. Smaller components, hence smaller PCBs.
3. Much higher levels of integration: I regularly design with
500 to 1000 pin ICs, whereas anything more than a hundred
or so pins would be beyond most through-hole packages.
The disadvantages of SMT are
1. Harder to rework - due to size and the soldering process
2. Expensive reflow soldering machines required.
3. Inspection is harder - solder joints under components require
X-ray laminography to inspect them, as opposed to visual or
optical inspection for through hole boards.
Through-hole machine assembly is possible but the machines
are more complicated.
Machine assembly is more consistent than hand assembly.
I have lived through the transition from through hole to SMT.
Quality of assembled PCBs is a better due to the higher level
of automation, but through hole boards were not all that bad.
In both cases the ability of the assembly line is more important
then the process.
SMT is suited to big manufacturers with large production runs,
and is very capital intensive. Cottage industries have to contract SMT assembly out, with higher unit costs for small runs, whereas through hole assembly can be done in the garage, or by small, cheap contractors with little setup charge.
Regarding Roger's observation on the inside of a JR radio:
I was similarly surprised a couple of 378s I've fixed for friends. The charging jack is soldered directly to one of the PCBs. The PCB is single-sided and the jack's mounting pads had lifted due to insertion of the charging cord. No plated through holes or mechanical reinforcing was used. The wiring looms were simply stripped and soldered directly to pads on the PCBs. There were separate PCBs for the display, front panel buttons, main processor board, RF board, with wires running everywhere. The design of the case made all the boards necessary since nothing really lined up with anything else.
My 9Z has a display board, processor board, RF board and some little boards for the switches. But at least it has good quality connectors and plug-in cables. Case opening and closing requires considerable dexterity. They clearly stopped designing the moment they found had somewhere to put all the parts. I have not seen inside an 10X, so I can't comment on them.
I have looked at a Profi 4000. A couple of boards, jointed by cables and connectors, and a case that was designed to be easily opened closed. Looking at it you would wonder "Is this all I get for my money?": the inside was so simple and clean. I mean this as a good thing, by the way.
Off-topic comment but something I think Multiplex need to think about:
Part of this came from the switched being on the front - which I personally don't like. I prefer switches on the top and side where they are easy to reach and identify by feel while holding the transmitter, but I suppose that's what I'm used to. One thing I found when I was rallying was that the switches for driving lights, intercom, and other gadgets were best spread at random all over the place where they could be easily identified by feel. Nice neat rows were not good since I had to count them off from the end - not easy while bouncing around on a logging road barely in control of the car.
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Hitec buys Multiplex - 
Mpx RE 12 - 
