What soldering technique was used for this board... Reflow or wave soldering?

[onemanonelaptop]

I have a board from the Early 90's, a motherboard for a Sega Game Gear. I am trying to figure out what method they used to solder these together, looking at the picture below i am leaning towards wave soldering.



There seems to be a stackup of solder consistently on the left side of each component, that coupled with some legs of some components having solder higher upthem than i would normally expect from reflow solder.

Also... the large ASICs have enlarged pads on the corners, which "might" be for solder capture.




However there appears to be NO glue holding any components down (bar some of the electrolyitcs) as far as i can tell..... I dont know much about SMD wave soldering, but not sure how they would ever stay in place without glue, which ive seen red blobs of on other PCB's which i know for a fact were wave soldered.

What do you think? Wave soldered or Reflow soldered?

[SMTech]

Reflow.

Were it wave all the vias in your second picture would be full of solder, it is also common to see IC's rotated 45degrees with kite-shaped pads at the front corners.

Is the first image a different board / side? That destroyed area with the missing part looks a bit like there was glue there and the board style is different.

[onemanonelaptop]

Its the same board, just the back of it,

[Bud]

Surface tension of molten solder holds components in place. No glue needed unless it is a heavy component.

[SMTech]

Surface tension of molten solder holds components in place. No glue needed unless it is a heavy component.

You glue for wave, because there is no solder......

[SMTech]

Its the same board, just the back of it,

Looking at a full PCB picture - that side could be wave soldered, the THT parts are on the other side after all, so there's a reason to wave. Would explain the masked vias, excess solder and apparent single axis shift of all the components. 

[Matt-Brown]

Looks like asic side was reflow and first picture proablly reflow and wave solder. the component shift could be placement of smt machines being off as they dont move in wave, but will usually fall off

[wraper]

Looks like wave soldering. I can see adhesive on the top picture and IC footprints suggest wave soldering as well.