It's not that easy. 😀
Without having done any research other than a 1 minut Googling and looking at and testing probably 100+ motherboards using PC Chips designs this is how I think it is.
PC Chips is the in-house brand name PC Chips Group used for many of their motherboard designs, they also sold those designs to other companies. Hsing Tech Enterprise was their in-house manufacturing plant that also made boards for some of those who bought PC Chips designs.
Elpina was a contract board manufacturing company that among other components made motherboards for other companies. During the late 90s I guess Hsing Tech couldn't keep up on their own so PC Chips let Elpina make many of their boards and probably also boards for some of those who bought designs from PC Chips.
The PC Chips motherboards made by Elpina are of good quality but often use cheap capacitors. One example of such a board is the PC Chips M577 with VIA MVP3 chipset, a very solid motherboard (at least when made by Elpina).
Some of the PC Chips Slot-1 designs made by Elpina really suck but I doubt that has anything to do with Elpina or even very much with PC Chips... Some of those early cheap (non Intel) P6 chipsets were just god-awful regardless of who designed or made the motherboards.
Main PC: Dual Xeon X5690@4.6ghz, Evga - SR-2, 48gb memory, Intel X25-M g2 SSD and a Nvidia GTX 980 ti.
Retro PC #3: K6-2 450@500mhz, PC-Chips m577, 256mb sdram, AWE64 and a Voodoo Banshee.